:root{--bg:#f8fafc;--bg-card:#fff;--bg-sidebar:#fff;--bg-topbar:#ffffffeb;--border:#e2e8f0;--text:#0f172a;--text-muted:#64748b;--text-light:#94a3b8;--accent:#2563eb;--accent-light:#eff6ff;--accent-border:#bfdbfe;--red:#dc2626;--red-bg:#fef2f2;--red-border:#fecaca;--green:#16a34a;--green-bg:#f0fdf4;--green-border:#bbf7d0;--blue:#2563eb;--blue-bg:#eff6ff;--blue-border:#bfdbfe;--topbar-h:56px;--sidebar-w:272px;--radius:.75rem;--shadow-sm:0 1px 3px #00000014;--shadow-md:0 4px 16px #0000001a}[data-theme=dark]{--bg:#0d1117;--bg-card:#161b22;--bg-sidebar:#161b22;--bg-topbar:#0d1117f2;--border:#30363d;--text:#e6edf3;--text-muted:#8b949e;--text-light:#6e7681;--accent:#58a6ff;--accent-light:#1c2d4a;--accent-border:#1f6feb;--red-bg:#2d1b1b;--red-border:#6b2020;--green-bg:#1b2d1b;--green-border:#1f4d1f;--blue-bg:#1c2d4a;--blue-border:#1f6feb}*,:before,:after{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{background:var(--bg);color:var(--text);font-family:Inter,Segoe UI,system-ui,-apple-system,sans-serif;font-size:15px;line-height:1.6}a{color:inherit;text-decoration:none}img{max-width:100%}.topbar{height:var(--topbar-h);background:var(--bg-topbar);border-bottom:1px solid var(--border);-webkit-backdrop-filter:blur(12px);z-index:200;align-items:center;gap:1rem;padding:0 1rem;display:flex;position:fixed;top:0;left:0;right:0}.sidebar-toggle{color:var(--text-muted);cursor:pointer;background:0 0;border:none;border-radius:.375rem;flex-shrink:0;padding:.35rem;line-height:0;transition:background .15s,color .15s;display:flex}.sidebar-toggle:hover{background:var(--border);color:var(--text)}.topbar-logo{color:var(--accent);white-space:nowrap;flex-shrink:0;align-items:center;gap:.5rem;font-size:1rem;font-weight:700;display:flex}.topbar-logo-icon{font-size:1.25rem}.topbar-grades{flex:1;justify-content:center;gap:.375rem;display:flex}.topbar-grade{border:1.5px solid #0000;border-radius:999px;padding:.3rem .875rem;font-size:.85rem;font-weight:600;transition:all .18s}.grade-red{background:var(--red-bg);color:var(--red);border-color:var(--red-border)}.grade-green{background:var(--green-bg);color:var(--green);border-color:var(--green-border)}.grade-blue{background:var(--blue-bg);color:var(--blue);border-color:var(--blue-border)}.grade-red.active,.grade-red:hover{background:var(--red);color:#fff;border-color:var(--red)}.grade-green.active,.grade-green:hover{background:var(--green);color:#fff;border-color:var(--green)}.grade-blue.active,.grade-blue:hover{background:var(--blue);color:#fff;border-color:var(--blue)}.topbar-right{align-items:center;gap:.5rem;margin-left:auto;display:flex}.topbar-tools-link{color:#7c3aed;white-space:nowrap;background:#f5f3ff;border:1.5px solid #ddd6fe;border-radius:999px;align-items:center;gap:.3rem;padding:.3rem .8rem;font-size:.82rem;font-weight:600;transition:all .18s;display:flex}.topbar-tools-link:hover{color:#fff;background:#7c3aed;border-color:#7c3aed}[data-theme=dark] .topbar-tools-link{color:#a78bfa;background:#2d1f4e;border-color:#4c1d95}[data-theme=dark] .topbar-tools-link:hover{color:#fff;background:#7c3aed;border-color:#7c3aed}.theme-toggle{border:1px solid var(--border);color:var(--text-muted);cursor:pointer;background:0 0;border-radius:.5rem;padding:.375rem;line-height:0;transition:all .18s}.theme-toggle:hover{background:var(--border);color:var(--text)}.icon-moon,[data-theme=dark] .icon-sun{display:none}[data-theme=dark] .icon-moon{display:block}.app-shell{margin-top:var(--topbar-h);min-height:calc(100vh - var(--topbar-h));display:flex}.sidebar{width:var(--sidebar-w);background:var(--bg-sidebar);border-right:1px solid var(--border);top:var(--topbar-h);height:calc(100vh - var(--topbar-h));scrollbar-width:thin;scrollbar-color:var(--border) transparent;flex-shrink:0;transition:width .25s,opacity .25s;position:sticky;overflow:hidden auto}.sidebar-collapsed .sidebar{opacity:0;pointer-events:none;border-right:none;width:0;overflow:hidden}.sidebar-collapsed .content-area{max-width:none}.sidebar-inner{padding:1rem 0 2rem}.sidebar-grade-section{border-bottom:1px solid var(--border)}.sidebar-grade-btn{width:100%;color:var(--text);cursor:pointer;text-align:left;background:0 0;border:none;align-items:center;gap:.6rem;padding:.75rem 1rem;font-size:.9rem;font-weight:700;transition:background .15s;display:flex}.sidebar-grade-btn:hover{background:var(--border)}.grade-dot{border-radius:50%;flex-shrink:0;width:8px;height:8px}.grade-dot-red{background:var(--red)}.grade-dot-green{background:var(--green)}.grade-dot-blue{background:var(--blue)}.chevron{color:var(--text-muted);flex-shrink:0;margin-left:auto;transition:transform .2s}.is-open>.sidebar-grade-btn .chevron{transform:rotate(180deg)}.sidebar-chapters{padding:0 0 .5rem;display:none}.is-open>.sidebar-chapters{display:block}.sidebar-chapter{margin-bottom:.25rem}.sidebar-chapter-label{text-transform:uppercase;letter-spacing:.07em;color:var(--text-light);padding:.4rem 1rem .25rem 1.5rem;font-size:.72rem;font-weight:600}.sidebar-lessons{list-style:none}.sidebar-lesson{color:var(--text-muted);border-left:3px solid #0000;align-items:center;gap:.6rem;padding:.45rem 1rem .45rem 1.5rem;font-size:.85rem;line-height:1.35;transition:all .15s;display:flex}.sidebar-lesson:hover{color:var(--text);background:var(--accent-light);border-left-color:var(--accent-border)}.sidebar-lesson.is-active{color:var(--accent);background:var(--accent-light);border-left-color:var(--accent);font-weight:600}[data-grade="12"] .sidebar-lesson.is-active{color:var(--red);background:var(--red-bg);border-left-color:var(--red)}[data-grade="11"] .sidebar-lesson.is-active{color:var(--green);background:var(--green-bg);border-left-color:var(--green)}[data-grade="10"] .sidebar-lesson.is-active{color:var(--blue);background:var(--blue-bg);border-left-color:var(--blue)}[data-grade="12"] .sidebar-lesson:hover{background:var(--red-bg);border-left-color:var(--red-border);color:var(--red)}[data-grade="11"] .sidebar-lesson:hover{background:var(--green-bg);border-left-color:var(--green-border);color:var(--green)}[data-grade="10"] .sidebar-lesson:hover{background:var(--blue-bg);border-left-color:var(--blue-border);color:var(--blue)}[data-grade="12"] .sidebar-chapter-label{color:var(--red)}[data-grade="11"] .sidebar-chapter-label{color:var(--green)}[data-grade="10"] .sidebar-chapter-label{color:var(--blue)}.lesson-dot{opacity:.5;background:currentColor;border-radius:50%;flex-shrink:0;width:5px;height:5px}.sidebar-lesson.is-active .lesson-dot{opacity:1}.sidebar-overlay{z-index:150;background:#0006;display:none;position:fixed;inset:0}.content-area{flex:1;min-width:0;max-width:860px;padding:2.5rem 2rem}.tabs{border-bottom:2px solid var(--border);top:var(--topbar-h);z-index:100;background:var(--bg);gap:0;margin-bottom:2rem;margin-left:-2rem;margin-right:-2rem;padding-left:2rem;padding-right:2rem;transition:box-shadow .2s;display:flex;position:sticky}.tabs.is-stuck{box-shadow:0 2px 8px #00000014}[data-theme=dark] .tabs.is-stuck{box-shadow:0 2px 8px #00000059}.tab-btn{color:var(--text-muted);cursor:pointer;white-space:nowrap;background:0 0;border:none;border-bottom:2px solid #0000;align-items:center;gap:.45rem;margin-bottom:-2px;padding:.65rem 1.25rem;font-size:.88rem;font-weight:600;transition:all .18s;display:flex}.tab-btn svg{flex-shrink:0}.tab-btn:hover{color:var(--text);background:var(--border)}.tab-btn.is-active{color:var(--accent);border-bottom-color:var(--accent)}.tab-panel{display:none}.tab-panel.is-active{display:block}.prose{color:var(--text);font-family:Times New Roman,Cambria,serif;font-size:1.15rem;line-height:1.8}.prose h1{margin:0 0 1.25rem;font-size:1.6rem;font-weight:800}.prose h2{border-bottom:1px solid var(--border);color:var(--text);margin:2rem 0 .75rem;padding-bottom:.4rem;scroll-margin-top:5rem;font-size:1.2rem;font-weight:700}.prose h3{color:var(--text);margin:1.5rem 0 .5rem;scroll-margin-top:5rem;font-size:1.05rem;font-weight:700}.prose p{margin-bottom:1rem}.prose ul,.prose ol{margin:.75rem 0 1rem 1.5rem}.prose li{margin-bottom:.35rem}.prose strong{color:var(--text);font-weight:700}.prose em{font-style:italic}.prose a{color:var(--accent);text-decoration:underline;text-decoration-color:var(--accent-border)}.prose a:hover{text-decoration-color:var(--accent)}.prose code{background:var(--border);border-radius:.3rem;padding:.1em .35em;font-family:Fira Code,Cascadia Code,monospace;font-size:.88em}.prose pre{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);margin:1rem 0;padding:1.25rem;overflow-x:auto}.prose pre code{background:0 0;padding:0;font-size:.9rem}.prose table{border-collapse:collapse;width:100%;margin:1.25rem 0;font-size:.9rem}.prose th{background:var(--accent-light);color:var(--accent);border:1px solid var(--accent-border);text-align:center;padding:.6rem 1rem;font-weight:700}.prose td{border:1px solid var(--border);text-align:center;padding:.55rem 1rem}.prose tr:nth-child(2n) td{background:var(--bg)}.prose blockquote{border-left:4px solid var(--accent);background:var(--accent-light);border-radius:0 var(--radius) var(--radius) 0;color:var(--text-muted);margin:1rem 0;padding:.75rem 1.25rem}.prose .math-display{background:var(--bg-card);border-left:4px solid var(--accent);border-radius:0 var(--radius) var(--radius) 0;box-shadow:var(--shadow-sm);margin:1.25rem 0;padding:1rem 1.25rem;overflow-x:auto}.katex-display{overflow:auto hidden}.theorem,.dinh-nghia{background:var(--accent-light);border:1px solid var(--accent-border);border-left:4px solid var(--accent);border-radius:var(--radius);margin:1.5rem 0;padding:1rem 1.25rem}.theorem-title,.dinh-nghia-title{text-transform:uppercase;letter-spacing:.08em;color:var(--accent);margin-bottom:.5rem;font-size:.75rem;font-weight:700}.example{background:var(--green-bg);border-left:4px solid var(--green);border-radius:0 var(--radius) var(--radius) 0;margin:1.25rem 0;padding:.875rem 1.25rem}.example-title{text-transform:uppercase;letter-spacing:.08em;color:var(--green);margin-bottom:.4rem;font-size:.75rem;font-weight:700}.note{border-radius:0 var(--radius) var(--radius) 0;background:#fefce8;border-left:4px solid #eab308;margin:1.25rem 0;padding:.875rem 1.25rem}[data-theme=dark] .note{background:#2d2810}.note-title{text-transform:uppercase;letter-spacing:.08em;color:#a16207;margin-bottom:.4rem;font-size:.75rem;font-weight:700}.content-box{border-radius:var(--radius);margin:1.5rem 0;padding:1rem 1.25rem}.content-box__title{text-transform:uppercase;letter-spacing:.08em;margin-bottom:.5rem;font-size:.75rem;font-weight:700}.content-box__body{font-size:.95rem;line-height:1.7}.content-box__body p{margin-bottom:.75rem}.content-box__body p:last-child{margin-bottom:0}.content-box__body ul,.content-box__body ol{margin:.5rem 0 .75rem 1.25rem}.content-box__body li{margin-bottom:.3rem}.content-box.content-theorem{background:var(--accent-light);border:1px solid var(--accent-border);border-left:4px solid var(--accent)}.content-box.content-theorem .content-box__title{color:var(--accent)}.content-box.content-example{background:var(--green-bg);border:1px solid var(--green-border);border-left:4px solid var(--green)}.content-box.content-example .content-box__title{color:var(--green)}.content-box.content-note{background:#fefce8;border:1px solid #fde68a;border-left:4px solid #eab308}[data-theme=dark] .content-box.content-note{background:#2d2810;border-color:#4a3f1a}.content-box.content-note .content-box__title{color:#a16207}.content-box.content-method{background:#f5f3ff;border:1px solid #ddd6fe;border-left:4px solid #7c3aed}[data-theme=dark] .content-box.content-method{background:#1e1538;border-color:#3b2d6b}.content-box.content-method .content-box__title{color:#7c3aed}.content-box.content-warning{background:linear-gradient(135deg,#fffbeb,#fef3c7);border-left:4px solid #d97706}[data-theme=dark] .content-box.content-warning{background:linear-gradient(135deg,#1c1a05,#1a1505);border-left-color:#f59e0b}.content-box.content-warning .content-box__title{color:#b45309;font-weight:800}[data-theme=dark] .content-box.content-warning .content-box__title{color:#fbbf24}.content-warning{background:linear-gradient(135deg,#fffbeb,#fef3c7);border-left:4px solid #d97706;border-radius:.75rem;margin:1.25rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .content-warning{background:linear-gradient(135deg,#1c1a05,#1a1505);border-left-color:#f59e0b}.content-warning .content-box__title{color:#b45309;margin-bottom:.6rem;font-size:.95rem;font-weight:800}[data-theme=dark] .content-warning .content-box__title{color:#fbbf24}.content-warning .content-box__body{font-size:.95rem;line-height:1.7}.lmdx-content h2{scroll-margin-top:5rem;color:#1e40af!important;background:linear-gradient(90deg,#eff6ff,#f8faff)!important;border-bottom:none!important;border-left:4px solid #2563eb!important;border-radius:0 .6rem .6rem 0!important;margin:2.75rem 0 1rem!important;padding:.6rem 1rem .6rem 1.1rem!important;font-size:1.2rem!important;font-weight:800!important;box-shadow:0 1px 4px #2563eb12!important}.lmdx-content h2:first-child{margin-top:.5rem!important}[data-theme=dark] .lmdx-content h2{color:#93c5fd!important;background:linear-gradient(90deg,#0c1929,#111827)!important;border-left-color:#3b82f6!important}.lmdx-content h2.h2-dang{color:#9a3412!important;background:linear-gradient(90deg,#fff7ed,#fffbf5)!important;border-left-color:#ea580c!important}[data-theme=dark] .lmdx-content h2.h2-dang{color:#fb923c!important;background:linear-gradient(90deg,#1a0e04,#1c1207)!important;border-left-color:#f97316!important}.lmdx-content h3{scroll-margin-top:5rem;color:#14532d!important;background:#f0fdf4!important;border-left:3px solid #16a34a!important;border-radius:0 .45rem .45rem 0!important;margin:1.75rem 0 .6rem!important;padding:.35rem .85rem!important;font-size:1rem!important;font-weight:700!important}[data-theme=dark] .lmdx-content h3{color:#4ade80!important;background:#052e16!important;border-left-color:#22c55e!important}.lmdx-content hr{border:none;border-top:2px dashed var(--border);margin:2.5rem 0}.content-note{background:linear-gradient(135deg,#ecfeff,#e0f7fa);border-left:4px solid #0891b2;border-radius:.75rem;margin:1.25rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .content-note{background:linear-gradient(135deg,#051e25,#0a1f2e);border-left-color:#22d3ee}.content-note .content-box__title{color:#0e7490;margin-bottom:.6rem;font-size:.95rem;font-weight:800}[data-theme=dark] .content-note .content-box__title{color:#67e8f9}.content-note .content-box__body{font-size:.95rem;line-height:1.7}.content-example{background:linear-gradient(135deg,#f5f3ff,#ede9fe);border-left:4px solid #7c3aed;border-radius:.75rem;margin:1.25rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .content-example{background:linear-gradient(135deg,#0f0a1e,#1a1033);border-left-color:#8b5cf6}.content-example .content-box__title{color:#6d28d9;margin-bottom:.6rem;font-size:.95rem;font-weight:800}[data-theme=dark] .content-example .content-box__title{color:#a78bfa}.content-example .content-box__body{font-size:.95rem;line-height:1.7}.content-method{background:linear-gradient(135deg,#fff7ed,#ffedd5);border-left:4px solid #ea580c;border-radius:.75rem;margin:1.25rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .content-method{background:linear-gradient(135deg,#1c1006,#1a1205);border-left-color:#f97316}.content-method .content-box__title{color:#c2410c;margin-bottom:.6rem;font-size:.95rem;font-weight:800}[data-theme=dark] .content-method .content-box__title{color:#fb923c}.content-method .content-box__body{font-size:.95rem;line-height:1.7}.content-theorem{background:linear-gradient(135deg,#eff6ff,#f0f4ff);border-left:4px solid #2563eb;border-radius:.75rem;margin:1.25rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .content-theorem{background:linear-gradient(135deg,#0c1929,#111827);border-left-color:#3b82f6}.content-theorem .content-box__title{color:#1d4ed8;margin-bottom:.6rem;font-size:.95rem;font-weight:800}[data-theme=dark] .content-theorem .content-box__title{color:#60a5fa}.content-theorem .content-box__body{font-size:.95rem;line-height:1.7}.content-tuluan{background:linear-gradient(135deg,#eef2ff,#e8ecff);border:2px solid #c7d2fe;border-radius:.85rem;margin:1.25rem 0;overflow:hidden}[data-theme=dark] .content-tuluan{background:linear-gradient(135deg,#0f0d1a,#131127);border-color:#3730a3}.content-tuluan__header{color:#fff;background:linear-gradient(135deg,#4f46e5,#4338ca);align-items:center;gap:.5rem;padding:.85rem 1.25rem;display:flex}.tuluan-icon{font-size:1.1rem}.tuluan-title{letter-spacing:.01em;font-size:.92rem;font-weight:800}.content-tuluan__body{padding:1.25rem 1.5rem;font-size:.95rem;line-height:1.7}.content-tuluan__body ol{margin:.5rem 0;padding-left:1.25rem}.content-tuluan__body li{margin:.4rem 0}.tuluan-link{background:linear-gradient(135deg,#4f46e5,#4338ca);border-radius:.65rem;justify-content:center;align-items:center;gap:.4rem;margin:0 1.25rem 1.25rem;padding:.75rem 1.25rem;font-size:.92rem;font-weight:700;text-decoration:none;transition:all .2s;display:flex;box-shadow:0 3px 12px #4f46e54d;color:#fff!important}.tuluan-link:hover{transform:translateY(-2px);box-shadow:0 5px 20px #4f46e566}.content-loigiai{border:1.5px solid var(--border);border-radius:.6rem;margin:.75rem 0;overflow:hidden}[data-theme=dark] .content-loigiai{border-color:#334155}.content-loigiai__toggle{cursor:pointer;color:#475569;user-select:none;background:#f8fafc;align-items:center;gap:.5rem;padding:.6rem 1rem;font-size:.88rem;font-weight:700;list-style:none;display:flex}.content-loigiai__toggle::-webkit-details-marker{display:none}[data-theme=dark] .content-loigiai__toggle{color:#94a3b8;background:#1e293b}.content-loigiai__toggle:hover{background:#f1f5f9}[data-theme=dark] .content-loigiai__toggle:hover{background:#1a2332}.loigiai-icon{font-size:1rem}.loigiai-chevron{flex-shrink:0;margin-left:auto;transition:transform .2s}.content-loigiai[open] .loigiai-chevron{transform:rotate(180deg)}.content-loigiai__body{border-top:1px solid var(--border);background:var(--bg-card);padding:1rem 1.25rem;font-size:.95rem;line-height:1.7}[data-theme=dark] .content-loigiai__body{background:#0f172a;border-top-color:#334155}.ex-mcq,.ex-fill{border:2px solid var(--border);background:var(--bg-card);border-radius:.85rem;margin:1rem 0;padding:1.25rem 1.5rem}[data-theme=dark] .ex-mcq,[data-theme=dark] .ex-fill{background:#0f172a;border-color:#334155}.ex-mcq-question,.ex-fill-question{color:var(--text);margin-bottom:.85rem;font-size:.95rem;font-weight:600;line-height:1.7}.ex-mcq-options{grid-template-columns:1fr 1fr;gap:.5rem;display:grid}@media (width<=560px){.ex-mcq-options{grid-template-columns:1fr}}.ex-mcq-opt{border:1.5px solid var(--border);background:var(--bg-card);cursor:pointer;text-align:left;color:var(--text);border-radius:.65rem;align-items:center;gap:.55rem;width:100%;padding:.65rem .9rem;font-family:inherit;font-size:.88rem;line-height:1.5;transition:all .15s;display:flex}[data-theme=dark] .ex-mcq-opt{color:#e2e8f0;background:#1e293b;border-color:#334155}.ex-mcq-opt:hover:not(:disabled){background:#eff6ff;border-color:#93c5fd;transform:translateY(-1px);box-shadow:0 2px 8px #3b82f61f}[data-theme=dark] .ex-mcq-opt:hover:not(:disabled){background:#1a2744;border-color:#3b82f6}.ex-mcq-opt:disabled{cursor:default}.ex-mcq-opt.ex-correct{background:#f0fdf4;border-color:#16a34a}.ex-mcq-opt.ex-wrong{background:#fef2f2;border-color:#dc2626}[data-theme=dark] .ex-mcq-opt.ex-correct{background:#052e16;border-color:#22c55e}[data-theme=dark] .ex-mcq-opt.ex-wrong{background:#2a0505;border-color:#ef4444}.ex-mcq-letter{border:2px solid var(--border);background:var(--bg);width:30px;height:30px;color:var(--text-muted);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;font-size:.75rem;font-weight:800;transition:all .15s;display:flex}.ex-mcq-text{flex:1}.ex-fill-input-row{flex-wrap:wrap;align-items:center;gap:.6rem;display:flex}.ex-fill-input{border:2px solid var(--border);min-width:160px;color:var(--text);background:var(--bg-card);border-radius:.65rem;outline:none;flex:1;padding:.65rem .9rem;font-family:inherit;font-size:1rem;font-weight:600;transition:border-color .15s}[data-theme=dark] .ex-fill-input{color:#e2e8f0;background:#1e293b;border-color:#334155}.ex-fill-input:focus{border-color:#3b82f6;box-shadow:0 0 0 3px #3b82f61f}.ex-fill-input:disabled{opacity:.6}.ex-fill-btn{color:#fff;cursor:pointer;background:#2563eb;border:none;border-radius:.65rem;padding:.65rem 1.25rem;font-size:.88rem;font-weight:700;transition:all .15s}.ex-fill-btn:hover{background:#1d4ed8;transform:translateY(-1px)}.ex-fill-btn:disabled{opacity:.4;cursor:default;transform:none}.ex-feedback{border-radius:.65rem;margin-top:.75rem;padding:.8rem 1rem;font-size:.88rem;line-height:1.6}.ex-fb-correct{background:#f0fdf4;border:1.5px solid #bbf7d0}.ex-fb-wrong{background:#fef2f2;border:1.5px solid #fecaca}[data-theme=dark] .ex-fb-correct{background:#052e16;border-color:#166534}[data-theme=dark] .ex-fb-wrong{background:#2a0505;border-color:#991b1b}.ex-fb-icon{margin-right:.4rem}.ex-fb-text{font-weight:700}.ex-fb-explain{color:var(--text);border-top:1px solid #00000014;align-items:flex-start;gap:.35rem;margin-top:.5rem;padding-top:.5rem;font-weight:500;display:flex}[data-theme=dark] .ex-fb-explain{color:#cbd5e1;border-top-color:#ffffff1a}.ex-fb-label{flex-shrink:0}.lmdx-lesson-nav{border-top:2px dashed var(--border);margin-top:2.5rem;padding-top:1.5rem}.lmdx-lesson-nav__inner{grid-template-columns:1fr 1fr;gap:1rem;display:grid}.lmdx-lesson-nav__btn{border:1.5px solid var(--border);background:var(--bg-card);color:inherit;border-radius:.75rem;align-items:center;gap:.75rem;min-width:0;padding:.9rem 1.1rem;transition:all .2s;display:flex;box-shadow:0 1px 4px #0000000a;text-decoration:none!important}.lmdx-lesson-nav__btn:hover{border-color:var(--accent);background:color-mix(in srgb, var(--accent) 8%, transparent);transform:translateY(-2px);box-shadow:0 4px 12px #0000001a}[data-theme=dark] .lmdx-lesson-nav__btn{background:#0f172a;border-color:#334155}[data-theme=dark] .lmdx-lesson-nav__btn:hover{background:color-mix(in srgb, var(--accent) 15%, transparent);border-color:var(--accent)}.lmdx-lesson-nav__btn--next{text-align:right;justify-content:flex-end}.lmdx-lesson-nav__arrow{color:var(--accent);flex-shrink:0;font-size:1.25rem;transition:transform .2s}.lmdx-lesson-nav__btn--prev:hover .lmdx-lesson-nav__arrow{transform:translate(-3px)}.lmdx-lesson-nav__btn--next:hover .lmdx-lesson-nav__arrow{transform:translate(3px)}.lmdx-lesson-nav__info{flex-direction:column;gap:.2rem;min-width:0;display:flex}.lmdx-lesson-nav__info--right{align-items:flex-end}.lmdx-lesson-nav__label{text-transform:uppercase;letter-spacing:.07em;color:var(--accent);opacity:.85;font-size:.7rem;font-weight:700}.lmdx-lesson-nav__title{color:var(--text);-webkit-line-clamp:2;-webkit-box-orient:vertical;font-size:.85rem;font-weight:600;line-height:1.35;display:-webkit-box;overflow:hidden}[data-theme=dark] .lmdx-lesson-nav__title{color:#e2e8f0}@media (width<=560px){.lmdx-lesson-nav__inner{grid-template-columns:1fr}.lmdx-lesson-nav__btn--next{text-align:left;justify-content:flex-start}.lmdx-lesson-nav__info--right{align-items:flex-start}}.lmdx-toc-fab{z-index:30;color:#fff;cursor:pointer;background:#2563eb;border:none;border-radius:50%;justify-content:center;align-items:center;width:48px;height:48px;transition:all .2s;display:none;position:fixed;bottom:1.25rem;right:1.25rem;box-shadow:0 4px 16px #2563eb59}.lmdx-toc-fab:hover{transform:scale(1.08)}@media (width<=960px){.lmdx-toc-fab{display:none!important}}.lmdx-toc-overlay{z-index:50;backdrop-filter:blur(4px);background:#0006;display:none;position:fixed;inset:0}.lmdx-toc-overlay.is-open{justify-content:flex-end;display:flex}.lmdx-toc-drawer{background:var(--bg-card);width:min(320px,85vw);height:100%;padding:1rem;animation:.2s slideIn;overflow-y:auto}@keyframes slideIn{0%{transform:translate(100%)}to{transform:translate(0)}}.lmdx-toc-drawer__header{border-bottom:1.5px solid var(--border);justify-content:space-between;align-items:center;margin-bottom:.75rem;padding-bottom:.75rem;font-size:.95rem;font-weight:800;display:flex}.lmdx-toc-drawer__header button{cursor:pointer;color:var(--text-muted);background:0 0;border:none;padding:.25rem;font-size:1.25rem}#tocNavMobile .toc-heading{padding:.6rem .7rem;font-size:.95rem}#tocNavMobile .toc-item{font-size:.85rem}.toc-section{margin-bottom:.75rem}.toc-section:last-child{margin-bottom:0}.toc-heading{cursor:pointer;user-select:none;box-sizing:border-box;width:100%;color:inherit;border-radius:.5rem;align-items:center;gap:.5rem;margin-bottom:.3rem;padding:.45rem .65rem;font-size:.8rem;font-weight:800;transition:all .18s;text-decoration:none!important;display:flex!important}.toc-heading:hover{transform:translate(2px)}.toc-icon{flex-shrink:0;font-size:.85rem}.toc-h-theory{background:#eff6ff;border-left:3px solid #3b82f6;color:#1d4ed8!important}.toc-h-theory:hover{background:#dbeafe!important}.toc-h-dang{background:#fff7ed;border-left:3px solid #f97316;color:#c2410c!important}.toc-h-dang:hover{background:#fed7aa!important}.toc-h-quiz{background:#fef2f2;border-left:3px solid #ef4444;color:#dc2626!important}.toc-h-quiz:hover{background:#fecaca!important}[data-theme=dark] .toc-h-theory{background:#1e2d4a;border-color:#3b82f6;color:#93c5fd!important}[data-theme=dark] .toc-h-theory:hover{background:#1a2744!important}[data-theme=dark] .toc-h-dang{background:#1c1a0e;border-color:#f97316;color:#fdba74!important}[data-theme=dark] .toc-h-dang:hover{background:#251a08!important}[data-theme=dark] .toc-h-quiz{background:#1c0a0a;border-color:#ef4444;color:#fca5a5!important}[data-theme=dark] .toc-h-quiz:hover{background:#250808!important}.toc-ext{opacity:.5;margin-left:auto;font-size:.7rem;transition:opacity .15s}.toc-h-quiz:hover .toc-ext{opacity:1}.toc-items-wrap{border-left:2px solid #e2e8f0;gap:.05rem;margin-bottom:.25rem;margin-left:.75rem;padding-left:.5rem;flex-direction:column!important;display:flex!important}[data-theme=dark] .toc-items-wrap{border-color:#1e293b}.toc-item{cursor:pointer;word-break:break-word;color:#64748b;border-radius:.35rem;padding:.28rem .55rem;font-size:.75rem;line-height:1.45;transition:all .15s;text-decoration:none!important;display:block!important}.toc-item:hover{transform:translate(2px)}.toc-item-blue:hover{background:#eff6ff;color:#1d4ed8!important}.toc-item-blue.is-active{background:#eff6ff;font-weight:700;color:#1d4ed8!important}.toc-item-orange:hover{background:#fff7ed;color:#c2410c!important}.toc-item-orange.is-active{background:#fff7ed;font-weight:700;color:#c2410c!important}[data-theme=dark] .toc-item{color:#94a3b8}[data-theme=dark] .toc-item-blue:hover,[data-theme=dark] .toc-item-blue.is-active{background:#1e293b;color:#60a5fa!important}[data-theme=dark] .toc-item-orange:hover,[data-theme=dark] .toc-item-orange.is-active{background:#1c1006;color:#fb923c!important}.lmdx-quiz-cta{text-align:center;background:linear-gradient(135deg,#fef2f2,#fff1f2,#fef2f2);border:2px solid #fecaca;border-radius:1.25rem;margin-top:3rem;padding:2.5rem 2rem;position:relative;overflow:hidden}.lmdx-quiz-cta:before{content:"";pointer-events:none;background:radial-gradient(at 50% 0,#dc26260f,#0000 70%);position:absolute;inset:0}[data-theme=dark] .lmdx-quiz-cta{background:linear-gradient(135deg,#1c0a0a,#1a0505);border-color:#7f1d1d}.quiz-cta-icon{margin-bottom:.5rem;font-size:3rem}.quiz-cta-title{color:#991b1b;margin-bottom:.5rem;font-size:1.25rem;font-weight:800}[data-theme=dark] .quiz-cta-title{color:#fca5a5}.quiz-cta-desc{color:var(--text-muted);max-width:400px;margin-bottom:1.25rem;margin-left:auto;margin-right:auto;font-size:.9rem;line-height:1.6}.quiz-cta-btn{border-radius:.75rem;align-items:center;gap:.5rem;padding:.85rem 2rem;font-size:1rem;font-weight:700;text-decoration:none;transition:all .2s;animation:2s ease-in-out infinite quiz-pulse;display:inline-flex;color:#fff!important}.quiz-cta-btn:hover{filter:brightness(1.1);transform:translateY(-3px)scale(1.02)}@keyframes quiz-pulse{0%,to{transform:scale(1)}50%{transform:scale(1.03)}}.quiz-cta-sub{color:var(--text-light);margin-top:.85rem;font-size:.76rem;font-weight:500}.quiz-container{flex-direction:column;gap:2rem;display:flex}.quiz-question-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);padding:1.5rem}.quiz-q-num{text-transform:uppercase;letter-spacing:.08em;color:var(--accent);margin-bottom:.6rem;font-size:.72rem;font-weight:700}.quiz-q-text{color:var(--text);margin-bottom:1.1rem;font-size:1rem;font-weight:600;line-height:1.5}.quiz-options{flex-direction:column;gap:.5rem;display:flex}.quiz-option-btn{border:1.5px solid var(--border);background:var(--bg);color:var(--text);cursor:pointer;text-align:left;border-radius:.5rem;align-items:center;gap:.75rem;padding:.7rem 1rem;font-size:.9rem;transition:all .15s;display:flex}.quiz-option-btn:hover:not(:disabled){border-color:var(--accent);background:var(--accent-light)}.quiz-option-btn.correct{border-color:var(--green);background:var(--green-bg);color:var(--green);font-weight:600}.quiz-option-btn.wrong{border-color:var(--red);background:var(--red-bg);color:var(--red)}.quiz-option-btn:disabled{cursor:default}.quiz-opt-letter{background:var(--border);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:28px;height:28px;font-size:.78rem;font-weight:700;transition:all .15s;display:flex}.quiz-option-btn.correct .quiz-opt-letter{background:var(--green);color:#fff}.quiz-option-btn.wrong .quiz-opt-letter{background:var(--red);color:#fff}.quiz-feedback{border-radius:.5rem;margin-top:.75rem;padding:.6rem .9rem;font-size:.875rem;font-weight:600;display:none}.quiz-feedback.show{display:block}.quiz-feedback.correct{background:var(--green-bg);color:var(--green)}.quiz-feedback.wrong{background:var(--red-bg);color:var(--red)}.quiz-score{text-align:center;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);padding:2rem}.quiz-score-num{color:var(--accent);margin-bottom:.5rem;font-size:3rem;font-weight:800;line-height:1}.quiz-score-label{color:var(--text-muted);margin-bottom:1.25rem;font-size:.95rem}.quiz-restart-btn{background:var(--accent);color:#fff;cursor:pointer;border:none;border-radius:.5rem;padding:.6rem 1.5rem;font-size:.9rem;font-weight:600;transition:opacity .18s}.quiz-restart-btn:hover{opacity:.85}.lesson-header{border-bottom:1px solid var(--border);margin-bottom:2rem;padding-bottom:1.25rem}.lesson-breadcrumb{color:var(--text-muted);align-items:center;gap:.4rem;margin-bottom:.5rem;font-size:.8rem;display:flex}.lesson-breadcrumb a{color:var(--text-muted);transition:color .15s}.lesson-breadcrumb a:hover{color:var(--accent)}.lesson-title{color:var(--text);margin-bottom:.5rem;font-size:1.75rem;font-weight:800;line-height:1.25}.lesson-desc{color:var(--text-muted);font-size:.95rem}.dang-bai-list{flex-direction:column;gap:1.5rem;display:flex}.dang-bai-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);overflow:hidden}.dang-bai-header{background:var(--accent-light);border-bottom:1px solid var(--accent-border);color:var(--accent);padding:1rem 1.25rem;font-size:.95rem;font-weight:700}.dang-bai-body{padding:1.25rem}.dang-bai-body .prose h3{margin-top:0}.home-hero{min-height:calc(100vh - var(--topbar-h));text-align:center;background:var(--bg);justify-content:center;align-items:center;padding:3rem 1.5rem;display:flex}.home-hero-inner{max-width:640px}.home-badge{background:var(--accent-light);color:var(--accent);border:1px solid var(--accent-border);border-radius:999px;margin-bottom:1.5rem;padding:.3rem .875rem;font-size:.8rem;font-weight:600;display:inline-block}.badge-dot{background:var(--accent);vertical-align:middle;border-radius:50%;width:6px;height:6px;margin-right:.4rem;animation:2s infinite pulse;display:inline-block}@keyframes pulse{0%,to{opacity:1;transform:scale(1)}50%{opacity:.6;transform:scale(.85)}}.home-title{color:var(--text);margin-bottom:1rem;font-size:clamp(2rem,5vw,3.25rem);font-weight:800;line-height:1.15}.home-title-accent{background:linear-gradient(135deg,#2563eb,#7c3aed);-webkit-text-fill-color:transparent;background-clip:text}.home-sub{color:var(--text-muted);margin-bottom:2.5rem;font-size:1.05rem;line-height:1.7}.home-cta{flex-wrap:wrap;justify-content:center;gap:1rem;display:flex}.cta-primary{background:var(--accent);color:#fff;border-radius:999px;align-items:center;gap:.5rem;padding:.75rem 1.75rem;font-size:.95rem;font-weight:700;transition:all .2s;display:inline-flex;box-shadow:0 4px 12px #2563eb59}.cta-primary:hover{transform:translateY(-2px);box-shadow:0 6px 20px #2563eb73}.cta-secondary{background:var(--bg-card);color:var(--text);border:1.5px solid var(--border);border-radius:999px;align-items:center;gap:.5rem;padding:.75rem 1.75rem;font-size:.95rem;font-weight:600;transition:all .2s;display:inline-flex}.cta-secondary:hover{border-color:var(--accent);color:var(--accent);transform:translateY(-2px)}.home-stats{flex-wrap:wrap;justify-content:center;align-items:center;gap:1.5rem;margin:2rem 0;display:flex}.stat-item{text-align:center}.stat-num{color:var(--accent);font-size:1.75rem;font-weight:800;display:block}.stat-label{color:var(--text-muted);font-size:.78rem;font-weight:500}.stat-divider{background:var(--border);width:1px;height:36px}.home-grade-cards{text-align:left;grid-template-columns:repeat(3,1fr);gap:1rem;margin-top:3rem;display:grid}.home-grade-card{background:var(--bg-card);border:1.5px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);padding:1.25rem;transition:all .2s;display:block}.home-grade-card:hover{box-shadow:0 8px 24px var(--card-glow,#00000026);border-color:var(--card-clr,var(--accent));transform:translateY(-4px)}.home-grade-card.red:hover{border-color:var(--red)}.home-grade-card.green:hover{border-color:var(--green)}.home-grade-card.blue:hover{border-color:var(--blue)}.hgc-top{justify-content:space-between;align-items:flex-start;margin-bottom:.75rem;display:flex}.hgc-icon{flex-shrink:0;margin-bottom:.5rem;font-size:2rem}.hgc-badge{border-radius:999px;padding:.2rem .6rem;font-size:.72rem;font-weight:700;display:inline-block}.hgc-title{color:var(--text);margin-bottom:.4rem;font-size:1.1rem;font-weight:800}.hgc-desc{color:var(--text-muted);margin-bottom:1rem;font-size:.82rem;line-height:1.5}.hgc-arrow{color:var(--text-muted);align-items:center;transition:transform .2s,color .2s;display:flex}.home-grade-card:hover .hgc-arrow{color:var(--card-clr,var(--accent));transform:translate(4px)}.math-bg{pointer-events:none;z-index:0;position:fixed;inset:0;overflow:hidden}.math-sym{left:var(--x);top:var(--y);font-size:var(--s,1.5rem);color:var(--accent);opacity:.06;animation:float var(--t,20s) var(--d,0s) ease-in-out infinite alternate;user-select:none;font-family:Times New Roman,serif;position:absolute}[data-theme=dark] .math-sym{opacity:.04}@keyframes float{0%{transform:translateY(0)rotate(0)}to{transform:translateY(-30px)rotate(10deg)}}.home-footer{border-top:1px solid var(--border);background:var(--bg);padding:2.5rem 1.5rem}.home-footer-inner{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:1rem;max-width:640px;margin:0 auto;display:flex}.footer-brand{align-items:center;gap:.5rem;font-weight:700;display:flex}.footer-logo-icon{font-size:1.25rem}.footer-brand-name{color:var(--accent)}.footer-nav{flex-wrap:wrap;align-items:center;gap:.75rem;display:flex}.footer-link{color:var(--text-muted);align-items:center;gap:.35rem;font-size:.82rem;font-weight:500;transition:color .15s;display:flex}.footer-link:hover{color:var(--accent)}.footer-sep{color:var(--border)}.footer-copy{color:var(--text-light);text-align:center;width:100%;margin-top:.5rem;font-size:.75rem}.lmdx-article{width:100%;padding-bottom:3rem}.lmdx-hero{background:linear-gradient(135deg, var(--hero-from,#1e3a5f), var(--hero-to,#1e40af));color:#fff;border-radius:1.25rem;align-items:center;gap:1.5rem;margin-bottom:1rem;padding:2.25rem 2rem 2rem;display:flex;position:relative;overflow:hidden}.lmdx-hero:before{content:"";background:radial-gradient(ellipse at 85% 50%, color-mix(in srgb, var(--hero-accent,#93c5fd) 20%, transparent), transparent 65%);pointer-events:none;position:absolute;inset:0}.lmdx-hero__content{z-index:1;flex:1;padding:0;position:relative}.lmdx-hero__art{opacity:.9;z-index:1;flex-shrink:0;width:220px;position:relative}.lmdx-breadcrumb{color:#ffffffa6;flex-wrap:wrap;align-items:center;gap:.4rem;margin-bottom:.75rem;font-size:.78rem;display:flex}.lmdx-breadcrumb a{color:#fffc;transition:color .15s}.lmdx-breadcrumb a:hover{color:#fff}.lmdx-hero__title{color:#fff;margin:0 0 .6rem;font-size:clamp(1.4rem,3.5vw,2rem);font-weight:800;line-height:1.2}.lmdx-hero__desc{color:#ffffffd1;max-width:520px;margin:0 0 1rem;font-size:.95rem;line-height:1.55}.lmdx-hero__chips{flex-wrap:wrap;gap:.4rem;display:flex}.hero-chip{color:#ffffffe6;background:#ffffff24;border:1px solid #ffffff38;border-radius:999px;padding:.25rem .75rem;font-size:.75rem;font-weight:600;display:inline-block}.lmdx-layout{grid-template-columns:1fr 250px;align-items:start;gap:2rem;display:grid}.lmdx-content{min-width:0;font-size:.95rem;line-height:1.75}.lmdx-toc{top:calc(var(--topbar-h) + 1rem);background:var(--bg-card);border:1.5px solid var(--border);max-height:calc(100vh - var(--topbar-h) - 2rem);scrollbar-width:thin;scrollbar-color:var(--border) transparent;border-radius:.85rem;align-self:start;padding:1rem .85rem;font-size:.82rem;position:sticky;overflow-y:auto;box-shadow:0 2px 10px #0000000a}.lmdx-toc__inner{background:var(--bg-card);border:1.5px solid var(--border);border-radius:.85rem;padding:1rem .85rem;box-shadow:0 2px 10px #0000000a}.lmdx-toc-title{text-transform:uppercase;letter-spacing:.08em;color:var(--text-light);border-bottom:1.5px solid var(--border);margin-bottom:.75rem;padding-bottom:.5rem;font-size:.72rem;font-weight:800}.lmdx-toc-list{flex-direction:column;gap:.3rem;list-style:none;display:flex}.lmdx-toc-list a{color:var(--text-muted);line-height:1.4;transition:color .15s}.lmdx-toc-list a:hover{color:var(--accent)}.lmdx-toc-list li.active>a{color:var(--accent);font-weight:600}.tools-hero{text-align:center;background:linear-gradient(180deg, var(--accent-light) 0%, var(--bg) 100%);border-bottom:1px solid var(--border);margin:-2.5rem -2rem 2rem;padding:3rem 2rem 2rem}.tools-hero-inner{max-width:560px;margin:0 auto}.tools-badge{background:var(--accent-light);color:var(--accent);border:1px solid var(--accent-border);border-radius:999px;margin-bottom:.75rem;padding:.25rem .75rem;font-size:.78rem;font-weight:700;display:inline-block}.tools-title{color:var(--text);margin-bottom:.5rem;font-size:2rem;font-weight:800}.tools-desc{color:var(--text-muted);font-size:.95rem;line-height:1.65}.tools-section{margin-bottom:2.5rem}.tools-section-header{border-bottom:2px solid var(--border);align-items:center;gap:.6rem;margin-bottom:1rem;padding-bottom:.6rem;display:flex}.tools-section-header h2{color:var(--text);font-size:1rem;font-weight:700}.section-icon{font-size:1.2rem}.tools-section-header.grade-10{border-bottom-color:var(--blue)}.tools-section-header.grade-11{border-bottom-color:var(--green)}.tools-section-header.grade-12{border-bottom-color:var(--red)}.tools-grid{grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:1rem;display:grid}.tool-card{background:var(--bg-card);border:1.5px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-sm);align-items:center;gap:1rem;padding:1.1rem 1.25rem;transition:all .2s;display:flex}.tool-card:hover{box-shadow:var(--shadow-md);border-color:var(--accent);transform:translateY(-3px)}.tool-card--featured{background:linear-gradient(135deg, var(--accent-light), var(--bg-card));border-color:var(--accent-border);grid-column:span 2}.tool-card-icon{background:var(--accent-light);border:1px solid var(--accent-border);border-radius:.75rem;flex-shrink:0;justify-content:center;align-items:center;width:52px;height:52px;font-size:1.5rem;display:flex}.tool-card-body{flex:1;min-width:0}.tool-card-title{color:var(--text);margin-bottom:.3rem;font-size:.95rem;font-weight:700}.tool-card-desc{color:var(--text-muted);margin-bottom:.5rem;font-size:.82rem;line-height:1.45}.tool-card-tags{flex-wrap:wrap;gap:.35rem;display:flex}.tool-tag{background:var(--accent-light);color:var(--accent);border:1px solid var(--accent-border);border-radius:999px;padding:.15rem .55rem;font-size:.68rem;font-weight:600;display:inline-block}.tool-card-arrow{color:var(--text-muted);flex-shrink:0;font-size:1.2rem;transition:transform .2s}.tool-card:hover .tool-card-arrow{color:var(--accent);transform:translate(4px)}.tool-breadcrumb{color:var(--text-muted);flex-wrap:wrap;align-items:center;gap:.4rem;margin-bottom:1.5rem;font-size:.82rem;display:flex}.tool-breadcrumb a{color:var(--text-muted);transition:color .15s}.tool-breadcrumb a:hover{color:var(--accent)}.bc-sep{color:var(--text-light)}.bc-current{color:var(--text);font-weight:600}.tool-page-hero{color:#fff;text-align:center;border-radius:1rem;margin-bottom:1.5rem;padding:2.5rem 2rem;position:relative;overflow:hidden}.tool-page-hero:before{content:"";pointer-events:none;background:radial-gradient(circle at 20% 80%,#4f46e580 0%,#0000 60%),radial-gradient(circle at 80% 20%,#0ea5e966 0%,#0000 50%);position:absolute;inset:0}.tool-page-hero-inner{z-index:1;position:relative}.tool-page-badge{background:#ffffff26;border:1px solid #ffffff40;border-radius:999px;margin-bottom:.75rem;padding:.3rem .9rem;font-size:.78rem;font-weight:600;display:inline-block}.tool-page-title{margin-bottom:.5rem;font-size:1.9rem;font-weight:900;line-height:1.2}.tool-page-subtitle{opacity:.95;margin-bottom:.6rem;font-family:Times New Roman,serif;font-size:1.4rem}.tool-page-desc{opacity:.85;max-width:580px;margin:0 auto;font-size:.92rem;line-height:1.65}.tool-tab-hint{background:var(--bg-card);border:1px solid var(--border);color:var(--text-muted);border-radius:.75rem;margin-bottom:1.5rem;padding:.75rem 1.25rem;font-size:.83rem;line-height:1.7}.hint-icon{font-size:1rem}.tool-component-wrap{background:var(--bg-card);border:1.5px solid var(--border);border-radius:1rem;margin-bottom:2.5rem;padding:1.5rem;box-shadow:0 2px 12px #0000000f}.tool-theory{margin-bottom:2.5rem}.tool-theory-title{color:var(--text);margin-bottom:1rem;font-size:1.15rem;font-weight:700}.theory-grid{grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:.75rem;display:grid}.theory-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem 1.5rem}.theory-card h3{color:#3b82f6;margin-bottom:.6rem;font-size:.95rem;font-weight:700}.theory-card ul{color:var(--text);padding-left:1.25rem;font-family:Times New Roman,serif;font-size:.88rem;line-height:1.8}.theory-card li{margin-bottom:.25rem}.tool-related{margin-bottom:2rem}.tool-related-title{color:var(--text);margin-bottom:.75rem;font-size:1.05rem;font-weight:700}.tool-related-grid{grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:.6rem;display:grid}.related-card{background:var(--bg-card);border:1px solid var(--border);color:var(--text-muted);border-radius:.6rem;align-items:center;gap:.6rem;padding:.7rem 1rem;font-size:.85rem;font-weight:600;text-decoration:none;transition:all .18s;display:flex}.related-card:hover{color:#3b82f6;background:#3b82f60f;border-color:#3b82f6}.related-icon{font-size:1.1rem}.tool-back{margin-bottom:2rem}.tool-back-link{color:#3b82f6;align-items:center;gap:.3rem;font-size:.9rem;font-weight:600;text-decoration:none;transition:opacity .15s;display:inline-flex}.tool-back-link:hover{opacity:.7}code{background-color:#8080801a;border-radius:4px;padding:.1rem .3rem}.sc-wrap{max-width:1100px;height:calc(100vh - var(--topbar-h,56px));box-sizing:border-box;grid-template-columns:1fr 280px;gap:1.5rem;margin:0 auto;padding:1.5rem 1.5rem 0;display:grid}.sc-main{background:var(--bg-card);border:1.5px solid var(--border);border-radius:20px;flex-direction:column;height:100%;min-height:0;display:flex;overflow:hidden}.sc-header{border-bottom:1px solid var(--border);background:var(--bg-card);flex-shrink:0;justify-content:space-between;align-items:center;padding:1rem 1.25rem;display:flex}.sc-header-left{align-items:center;gap:.75rem;display:flex}.sc-logo{background:linear-gradient(135deg,#2563eb,#7c3aed);border-radius:10px;justify-content:center;align-items:center;width:40px;height:40px;display:flex;box-shadow:0 4px 12px #7c3aed4d}.sc-logo svg{display:block}.sc-header-title{color:var(--text);letter-spacing:-.02em;font-size:1rem;font-weight:800}.sc-header-sub{color:var(--text-muted);font-size:.75rem;font-weight:500}.sc-clear-btn{border:1px solid var(--border);color:var(--text-muted);cursor:pointer;background:0 0;border-radius:999px;align-items:center;gap:.4rem;padding:.4rem .9rem;font-size:.8rem;font-weight:600;transition:all .2s;display:flex}.sc-clear-btn:hover{color:#ef4444;background:#ef44440d;border-color:#ef4444}.sc-chat{scroll-behavior:smooth;flex-direction:column;flex:1;gap:1rem;min-height:0;padding:1.25rem;display:flex;overflow-y:auto}.sc-chat::-webkit-scrollbar{width:5px}.sc-chat::-webkit-scrollbar-track{background:0 0}.sc-chat::-webkit-scrollbar-thumb{background:var(--border);border-radius:4px}.sc-msg{align-items:flex-start;gap:.75rem;animation:.25s cubic-bezier(.16,1,.3,1) msgIn;display:flex}.sc-msg--user{flex-direction:row-reverse}@keyframes msgIn{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}.sc-avatar{border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:34px;height:34px;font-size:.85rem;font-weight:700;display:flex}.sc-avatar--bot{color:#fff;background:linear-gradient(135deg,#2563eb,#7c3aed);font-size:1rem}.sc-avatar--user{color:#fff;background:linear-gradient(135deg,#0f172a,#334155);font-size:.75rem}[data-theme=dark] .sc-avatar--user{color:#0f172a;background:linear-gradient(135deg,#e2e8f0,#94a3b8)}.sc-bubble{border-radius:16px;max-width:82%;padding:.85rem 1.1rem;font-size:.935rem;line-height:1.65}.sc-bubble--bot{background:var(--bg);border:1px solid var(--border);border-top-left-radius:4px}[data-theme=dark] .sc-bubble--bot{background:#ffffff0a}.sc-bubble--user{color:#1e293b;word-break:break-all;background:#f1f5f9;border:1px solid #cbd5e1;border-top-right-radius:4px;font-family:Fira Code,Cascadia Code,Courier New,monospace}[data-theme=dark] .sc-bubble--user{color:#f8fafc;background:#334155;border-color:#475569}.sc-bubble-header{text-transform:uppercase;letter-spacing:.06em;color:var(--accent);justify-content:space-between;align-items:center;margin-bottom:.4rem;font-size:.72rem;font-weight:700;display:flex}.sc-copy-btn{color:var(--text-light);cursor:pointer;background:0 0;border:none;border-radius:4px;align-items:center;gap:.3rem;padding:.2rem .5rem;font-size:.65rem;font-weight:600;transition:all .2s;display:flex}.sc-copy-btn:hover{background:var(--accent-light);color:var(--accent)}.sc-copy-btn.is-success{color:#10b981}.sc-bubble-content p{color:var(--text);margin:0 0 .5rem}.sc-bubble-content p:last-child{margin-bottom:0}.sc-result{margin-top:.5rem}.sc-result-label{text-transform:uppercase;letter-spacing:.06em;color:var(--text-muted);margin-bottom:.35rem;font-size:.72rem;font-weight:600}.sc-result-value{color:var(--text);word-break:keep-all;padding:.25rem .5rem;font-size:1.15rem;font-weight:500;overflow-x:auto}[data-theme=dark] .sc-result-value{color:#e2e8f0}.sc-divider{border:none;border-top:1px dashed var(--border);width:100%;margin:1.5rem 0 .5rem}.sc-bubble--math{width:100%;background:0 0!important;border:none!important;padding:0 .5rem!important}.sc-bubble--math .sc-result-detail{margin-left:.5rem}.sc-table-wrapper{border:1px solid var(--border);background:var(--bg-card);border-radius:8px;width:max-content;min-width:280px;max-height:480px;margin-top:.8rem;overflow-y:auto}.sc-table{border-collapse:collapse;text-align:center;width:100%;font-size:1rem}.sc-table th{color:var(--accent);z-index:10;border-bottom:2px solid var(--border);border-right:1px solid var(--border);box-shadow:0 1px 0 var(--border);background:#7c3aed1a;padding:.75rem;font-weight:700;position:sticky;top:0}.sc-table td{border-bottom:1px dashed var(--border);border-right:1px dashed var(--border);color:var(--text);padding:.6rem;font-family:Times New Roman,serif}.sc-table th:last-child,.sc-table td:last-child{border-right:none}.sc-table tr:last-child td{border-bottom:none}.sc-table tr:nth-child(2n) td{background:#7c3aed05}[data-theme=dark] .sc-table th{background:#7c3aed26}[data-theme=dark] .sc-table tr:nth-child(2n) td{background:#7c3aed0d}.sc-result-detail{background:var(--accent-light);color:var(--text-muted);border-radius:8px;margin-top:.6rem;padding:.6rem .85rem;font-size:.83rem;line-height:1.6}.sc-result-detail strong{color:var(--text);font-weight:600}.sc-bubble--error .sc-result-value{color:#ef4444;background:#ef444412;border:1.5px solid #ef444440;border-radius:10px;padding:.75rem 1rem;font-family:inherit;font-size:.9rem;font-weight:500}.sc-examples{margin-top:.75rem}.sc-examples-title{color:var(--text-muted);margin-bottom:.4rem;font-size:.75rem;font-weight:600}.sc-example-chips{flex-wrap:wrap;gap:.4rem;display:flex}.sc-chip{color:var(--accent);cursor:pointer;background:linear-gradient(135deg,#2563eb14,#7c3aed14);border:1px solid #7c3aed40;border-radius:999px;padding:.3rem .75rem;font-family:Fira Code,monospace;font-size:.78rem;font-weight:600;transition:all .18s}.sc-chip:hover{background:var(--accent);color:#fff;border-color:var(--accent);transform:translateY(-1px)}.sc-typing{align-items:center;gap:4px;padding:.25rem 0;display:flex}.sc-typing span{background:var(--accent);border-radius:50%;width:7px;height:7px;animation:1.2s ease-in-out infinite typingDot}.sc-typing span:nth-child(2){animation-delay:.2s}.sc-typing span:nth-child(3){animation-delay:.4s}@keyframes typingDot{0%,80%,to{opacity:.4;transform:scale(.6)}40%{opacity:1;transform:scale(1)}}.sc-input-wrap{border-top:1px solid var(--border);background:var(--bg-card);flex-shrink:0;padding:1rem 1.25rem 1.25rem}.sc-input-box{background:var(--bg);border:1.5px solid var(--border);border-radius:14px;align-items:flex-end;gap:.6rem;padding:.6rem .6rem .6rem 1rem;transition:border-color .2s,box-shadow .2s;display:flex}.sc-input-box:focus-within{border-color:var(--accent);box-shadow:0 0 0 3px #2563eb1f}.sc-input{resize:none;color:var(--text);background:0 0;border:none;outline:none;flex:1;min-height:24px;max-height:120px;padding:0;font-family:Fira Code,Cascadia Code,Courier New,monospace;font-size:.95rem;line-height:1.5;overflow-y:auto}.sc-input::placeholder{color:var(--text-muted);font-family:inherit}.sc-send-btn{color:#fff;cursor:pointer;background:linear-gradient(135deg,#2563eb,#7c3aed);border:none;border-radius:10px;flex-shrink:0;justify-content:center;align-items:center;width:40px;height:40px;transition:all .2s;display:flex;box-shadow:0 2px 8px #7c3aed4d}.sc-send-btn:hover{transform:scale(1.05);box-shadow:0 4px 16px #7c3aed73}.sc-send-btn:active{transform:scale(.96)}.sc-input-hint{color:var(--text-light);flex-wrap:wrap;align-items:center;gap:.4rem;margin-top:.5rem;padding:0 .25rem;font-size:.73rem;display:flex}.sc-hint-sep{opacity:.4}.sc-sidebar{background:var(--bg-card);border:1.5px solid var(--border);border-radius:20px;height:100%;padding:1rem 0;overflow:hidden auto}.sc-sidebar::-webkit-scrollbar{width:4px}.sc-sidebar::-webkit-scrollbar-thumb{background:var(--border);border-radius:4px}.sc-ref-title{text-transform:uppercase;letter-spacing:.07em;color:var(--text-muted);border-bottom:1px solid var(--border);margin-bottom:.5rem;padding:0 1rem .75rem;font-size:.82rem;font-weight:800}.sc-ref-section{border-bottom:1px solid var(--border);padding:.6rem 1rem}.sc-ref-section:last-child{border-bottom:none}.sc-ref-label{text-transform:uppercase;letter-spacing:.06em;color:var(--accent);margin-bottom:.4rem;font-size:.72rem;font-weight:700}.sc-ref-items{flex-direction:column;gap:.2rem;display:flex}.sc-ref-item{justify-content:space-between;align-items:center;gap:.5rem;padding:.15rem 0;font-size:.78rem;display:flex}.sc-ref-item code{background:var(--accent-light);color:var(--accent);border:1px solid var(--accent-border);white-space:nowrap;cursor:pointer;border-radius:4px;padding:.1em .45em;font-family:Fira Code,monospace;font-size:.74rem;transition:all .15s}.sc-ref-item code:hover{background:var(--accent);color:#fff}.sc-ref-item span{color:var(--text-muted);text-align:right;flex-shrink:0;font-size:.74rem}@media (width<=960px){.topbar-grades,.tools-link-text{display:none}.topbar-tools-link{padding:.3rem .5rem}.sidebar{top:var(--topbar-h);height:calc(100vh - var(--topbar-h));z-index:180;box-shadow:var(--shadow-md);transition:transform .25s;position:fixed;left:0;transform:translate(-100%)}.sidebar.is-open{transform:translate(0)}.sidebar-overlay{pointer-events:none;opacity:0;transition:opacity .25s;display:block}.sidebar-overlay.is-visible{pointer-events:auto;opacity:1}.content-area{padding:1.5rem 1rem 5rem}.home-grade-cards,.lmdx-layout{grid-template-columns:1fr}.lmdx-toc,.lmdx-hero__art{display:none}.tools-grid{grid-template-columns:1fr}.tool-card--featured{grid-column:span 1}.tool-page-hero{padding:1.75rem 1.25rem}.tool-page-title{font-size:1.4rem}.tool-page-subtitle{font-size:1.1rem}.theory-grid,.tool-related-grid{grid-template-columns:1fr}.tool-tab-hint{font-size:.78rem}.content-box{margin:1.25rem 0;padding:.875rem 1rem}.content-box__body{font-size:.9rem}.dang-bai-card{border-radius:.5rem}.sc-wrap{height:auto;min-height:calc(100vh - var(--topbar-h,56px));grid-template-columns:1fr}.sc-main{height:80vh;min-height:500px}.sc-sidebar{display:none}.tabs{z-index:190;border-bottom:none;border-top:1px solid var(--border);background:var(--bg-topbar);-webkit-backdrop-filter:blur(12px);justify-content:stretch;margin:0;padding:0;position:fixed;inset:auto 0 0;box-shadow:0 -2px 12px #0000001a!important}[data-theme=dark] .tabs{box-shadow:0 -2px 12px #0006!important}.tab-btn{border-top:2px solid #0000;border-bottom:none;flex-direction:column;flex:1;justify-content:center;gap:.25rem;margin-top:-1px;margin-bottom:0;padding:.6rem .25rem .5rem;font-size:.7rem;font-weight:500}.tab-btn svg{width:22px;height:22px}.tab-btn.is-active{color:var(--accent);border-top-color:var(--accent);background:var(--accent-light);border-bottom-color:#0000}}@media (width<=640px){.home-footer-inner{text-align:center;flex-direction:column;align-items:center}}