:root{--hl-primary: #831843;--hl-primary-hover: #5c1d3d;--hl-primary-light: #f5f3ff;--hl-primary-border: #fcf1f5;--hl-primary-glow: rgba(92, 29, 61, .25);--hl-accent: #b8541a;--hl-accent-light: #eef2ff;--hl-accent-border: #fde68a;--hl-bg: #ffffff;--hl-surface: #ffffff;--hl-surface-elevated: #ffffff;--hl-surface-muted: #f8fafc;--hl-surface-glass: rgba(255, 255, 255, .88);--hl-surface-glass-border: rgba(226, 232, 240, .8);--hl-text: #22181c;--hl-text-secondary: #6e5f64;--hl-text-muted: #6e5f64;--hl-border: #e2e8f0;--hl-border-subtle: #f1f5f9;--hl-border-hover: #cbd5e1;--hl-shadow-xs: 0 1px 2px rgba(34, 24, 28, .04);--hl-shadow-sm: 0 1px 3px rgba(34, 24, 28, .06), 0 1px 2px rgba(34, 24, 28, .04);--hl-shadow-md: 0 4px 12px -2px rgba(34, 24, 28, .08), 0 2px 6px -1px rgba(34, 24, 28, .04);--hl-shadow-lg: 0 12px 28px -4px rgba(92, 29, 61, .12), 0 4px 12px -2px rgba(34, 24, 28, .04);--hl-shadow-glow: 0 0 24px rgba(92, 29, 61, .18);--topic-1-color: #831843;--topic-1-bg: #f5f3ff;--topic-1-border: rgba(92, 29, 61, .25);--topic-2-color: #d97706;--topic-2-bg: #fffbeb;--topic-2-border: rgba(217, 119, 6, .25);--topic-3-color: #b8541a;--topic-3-bg: #ecfeff;--topic-3-border: rgba(184, 84, 26, .25);--topic-4-color: #db2777;--topic-4-bg: #fdf2f8;--topic-4-border: rgba(219, 39, 119, .25);--topic-5-color: #b45309;--topic-5-bg: #fcfaf7;--topic-5-border: rgba(180, 83, 9, .25)}body.dark-mode,html.dark-mode,[data-theme=dark]{--hl-primary: #e58bb3;--hl-primary-hover: #f2a8cb;--hl-primary-light: rgba(92, 29, 61, .16);--hl-primary-border: rgba(229, 139, 179, .32);--hl-primary-glow: rgba(229, 139, 179, .22);--hl-accent: #fb923c;--hl-accent-light: rgba(99, 102, 241, .16);--hl-accent-border: rgba(129, 140, 248, .32);--hl-bg: #161214;--hl-surface: #111827;--hl-surface-elevated: #162032;--hl-surface-muted: #161214;--hl-surface-glass: rgba(34, 24, 28, .88);--hl-surface-glass-border: rgba(34, 27, 32, .8);--hl-text: #f8fafc;--hl-text-secondary: #cbd5e1;--hl-text-muted: #b8a6af;--hl-border: #221b20;--hl-border-subtle: #161214;--hl-border-hover: #3d3039;--hl-shadow-xs: 0 1px 2px rgba(0, 0, 0, .4);--hl-shadow-sm: 0 1px 3px rgba(0, 0, 0, .5);--hl-shadow-md: 0 4px 14px rgba(0, 0, 0, .45);--hl-shadow-lg: 0 12px 30px rgba(0, 0, 0, .6);--hl-shadow-glow: 0 0 28px rgba(229, 139, 179, .25);--topic-1-bg: rgba(92, 29, 61, .16);--topic-2-bg: rgba(217, 119, 6, .16);--topic-3-bg: rgba(184, 84, 26, .16);--topic-4-bg: rgba(219, 39, 119, .16);--topic-5-bg: rgba(180, 83, 9, .16)}html{scroll-behavior:smooth}body{background-color:var(--hl-bg);color:var(--hl-text);font-family:var(--font-sans, "Inter", system-ui, sans-serif);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}.ib-nav-header{background:var(--hl-surface-glass);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border-bottom:1px solid var(--hl-border);position:sticky;top:0;z-index:100;transition:background-color .2s ease,border-color .2s ease}.ib-nav-container{max-width:1200px;margin:0 auto;padding:.65rem 1.25rem;display:flex;align-items:center;justify-content:space-between;gap:1rem}.ib-nav-brand{font-family:var(--font-display, "Outfit", sans-serif);font-weight:800;font-size:1.25rem;color:var(--hl-text);text-decoration:none;display:inline-flex;align-items:center;gap:.5rem;transition:transform .2s ease}.ib-nav-brand:hover{transform:scale(1.02)}.ib-nav-brand>span{color:var(--hl-primary);font-weight:900}.ib-nav-links{display:flex;align-items:center;gap:.5rem}.ib-nav-links a{color:var(--hl-text-secondary);text-decoration:none;font-size:.85rem;font-weight:600;padding:.4rem .75rem;border-radius:9999px;transition:all .2s ease}.ib-nav-links a:hover,.ib-nav-links a.active{color:var(--hl-primary);background:var(--hl-primary-light)}.ib-theme-btn{background:var(--hl-surface-muted);border:1px solid var(--hl-border);color:var(--hl-text);width:38px;height:38px;border-radius:50%;display:inline-flex;align-items:center;justify-content:center;cursor:pointer;transition:all .2s ease}.ib-theme-btn:hover{background:var(--hl-primary-light);border-color:var(--hl-primary-border);color:var(--hl-primary);transform:rotate(15deg)}.ib-hero{position:relative;padding:1.15rem 0 .85rem;background:radial-gradient(circle at 50% 0%,rgba(92,29,61,.08) 0%,transparent 60%),linear-gradient(180deg,var(--hl-primary-light) 0%,var(--hl-bg) 100%);border-bottom:1px solid var(--hl-border);overflow:hidden}body.dark-mode .ib-hero{background:radial-gradient(circle at 50% 0%,rgba(229,139,179,.12) 0%,transparent 65%),linear-gradient(180deg,rgba(92,29,61,.1) 0%,var(--hl-bg) 100%)}.ib-hero-container{max-width:1060px;margin:0 auto;padding:0 1.25rem}.breadcrumb-nav{display:inline-flex;align-items:center;flex-wrap:wrap;gap:.35rem .5rem;font-size:.8125rem;color:var(--hl-text-muted);margin-bottom:.4rem;padding:.2rem .7rem;background:var(--hl-surface-glass);backdrop-filter:blur(8px);border:1px solid var(--hl-border);border-radius:9999px}.breadcrumb-nav a{color:var(--hl-primary);text-decoration:none;font-weight:600;transition:color .15s ease}.breadcrumb-nav a:hover{text-decoration:underline}.breadcrumb-separator{color:var(--hl-text-muted);opacity:.6}.guide-kicker{font-size:.75rem;font-weight:800;text-transform:uppercase;letter-spacing:.08em;color:var(--hl-primary);margin:0 0 .25rem}.ib-hero-title{font-family:var(--font-display, "Outfit", sans-serif);font-size:clamp(1.85rem,3.5vw + .5rem,2.75rem);font-weight:800;color:var(--hl-text);line-height:1.18;letter-spacing:-.025em;margin:0 0 .35rem}.ib-hero-desc{font-size:1rem;color:var(--hl-text-secondary);line-height:1.55;max-width:860px;margin:0 0 .55rem}.meta-pills{display:flex;flex-wrap:wrap;gap:.35rem;margin-top:.35rem}.meta-pill{display:inline-flex;align-items:center;gap:.4rem;padding:.28rem .7rem;border-radius:9999px;font-size:.78rem;font-weight:600;background:var(--hl-surface);border:1px solid var(--hl-border);color:var(--hl-text);box-shadow:var(--hl-shadow-xs);transition:all .2s ease}.meta-pill:hover{transform:translateY(-2px);border-color:var(--hl-primary-border);box-shadow:var(--hl-shadow-sm)}.meta-pill i{color:var(--hl-primary)}.meta-pill.pill-hl{background:var(--hl-primary-light);color:var(--hl-primary);border-color:var(--hl-primary-border)}.study-tabs-nav{display:flex;align-items:center;gap:.35rem;margin:.75rem 0 1rem;padding:.25rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface-glass);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);box-shadow:var(--hl-shadow-sm);position:sticky;top:3.75rem;z-index:40;overflow-x:auto;white-space:nowrap;scrollbar-width:none;-webkit-overflow-scrolling:touch}.study-tabs-nav::-webkit-scrollbar{display:none}.study-tab-btn{display:inline-flex;align-items:center;gap:.45rem;padding:.5rem 1rem;border:none;border-radius:10px;background:transparent;color:var(--hl-text-secondary);font-family:var(--font-display, "Outfit", sans-serif);font-size:.86rem;font-weight:700;cursor:pointer;transition:all .2s cubic-bezier(.16,1,.3,1);flex-shrink:0;user-select:none}.study-tab-btn:hover{color:var(--hl-primary);background:var(--hl-primary-light)}.study-tab-btn.active{color:#fff!important;background:linear-gradient(135deg,#831843,#b8541a);box-shadow:0 4px 14px #5c1d3d59}body.dark-mode .study-tab-btn.active{color:#161214!important;background:linear-gradient(135deg,#e58bb3,#fb923c);box-shadow:0 4px 16px #e58bb366}.study-tab-panel{display:none;animation:tabFadeSlideIn .22s cubic-bezier(.16,1,.3,1)}.study-tab-panel.active{display:block}@keyframes tabFadeSlideIn{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}.concept-card{margin-bottom:.95rem;padding:1.15rem 1.25rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);transition:all .2s ease}.concept-card:hover{box-shadow:var(--hl-shadow-md);border-color:var(--hl-primary-border)}.concept-header{display:flex;align-items:center;justify-content:space-between;gap:.5rem;margin-bottom:.6rem;padding-bottom:.45rem;border-bottom:1px solid var(--hl-border-subtle);flex-wrap:wrap}.concept-badge{display:inline-flex;align-items:center;gap:.35rem;padding:.2rem .55rem;border-radius:9999px;background:var(--hl-primary-light);color:var(--hl-primary);font-size:.72rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase}.concept-title{margin:0;font-family:var(--font-display, "Outfit", sans-serif);font-size:1.2rem;font-weight:800;color:var(--hl-text)}.concept-notes,.theory-list{margin:.4rem 0 0;padding-left:1.35rem;display:grid;gap:.45rem;color:var(--hl-text-secondary);line-height:1.65}.concept-notes li strong,.theory-list li strong{color:var(--hl-text)}.example-card,.worked-example{margin:.95rem 0;padding:1.15rem 1.25rem;border:1px solid var(--hl-border);border-left:4px solid var(--hl-primary);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-sm);transition:all .2s ease;position:relative}.example-card:hover,.worked-example:hover{box-shadow:var(--hl-shadow-md);border-color:var(--hl-primary-border);border-left-color:var(--hl-primary);transform:translateY(-2px)}.example-card h4{margin:0 0 .65rem;font-family:var(--font-display, "Outfit", sans-serif);font-size:1.1rem;font-weight:800;color:var(--hl-text);display:flex;align-items:center;gap:.5rem}.example-card h4:before{content:"\1f4a1";font-size:1.1rem}.example-card p{color:var(--hl-text-secondary);line-height:1.65;margin:.35rem 0}.figure-card,.study-svg-figure{margin:.95rem 0 1.25rem;padding:1.15rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);text-align:center;transition:all .2s ease}.figure-card:hover,.study-svg-figure:hover{box-shadow:var(--hl-shadow-md);border-color:var(--hl-primary-border)}.figure-card h3{font-family:var(--font-display, "Outfit", sans-serif);margin-top:0;font-size:1.1rem;font-weight:800;color:var(--hl-text)}.figure-card svg,.study-svg-figure svg{max-width:100%;height:auto;display:block;margin:.75rem auto}body.dark-mode .figure-card line[stroke="#cbd5e1"],body.dark-mode .figure-card line[stroke="var(--c-border, #cbd5e1)"]{stroke:#6e5f64}.practice-controls-bar{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:.5rem;margin-bottom:.85rem;padding:.65rem 1rem;border-radius:12px;border:1px solid var(--hl-border);background:var(--hl-surface-muted)}.practice-filter-group{display:inline-flex;align-items:center;gap:.35rem;flex-wrap:wrap}.practice-filter-btn{padding:.3rem .7rem;border-radius:9999px;border:1px solid var(--hl-border);background:var(--hl-surface);color:var(--hl-text-secondary);font-size:.78rem;font-weight:700;cursor:pointer;transition:all .15s ease}.practice-filter-btn:hover{border-color:var(--hl-primary-border);color:var(--hl-primary)}.practice-filter-btn.active{background:var(--hl-primary);color:#fff;border-color:var(--hl-primary);box-shadow:0 2px 6px #5c1d3d40}.practice-progress-pill{font-size:.8rem;font-weight:700;color:var(--hl-primary);display:inline-flex;align-items:center;gap:.4rem}.exercise-card,.exercise-item,.practice-item{min-width:0;margin:0 0 1rem;padding:1.15rem 1.25rem;border:1px solid var(--hl-border);border-left:4px solid var(--hl-primary);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);transition:border-color .18s ease,box-shadow .18s ease,transform .18s ease}.exercise-card:hover,.exercise-item:hover,.practice-item:hover,.exercise-card:focus-within,.exercise-item:focus-within,.practice-item:focus-within{border-color:var(--hl-primary-border);border-left-color:var(--hl-primary);box-shadow:var(--hl-shadow-md);transform:translateY(-2px)}.exercise-card.exercise-completed,.exercise-item.exercise-completed,.practice-item.exercise-completed{border-left-color:#b45309!important;background:linear-gradient(90deg,rgba(34,197,94,.04) 0%,var(--hl-surface) 30%)}.exercise-header,.practice-header{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:.5rem .75rem;margin-bottom:.85rem;padding-bottom:.65rem;border-bottom:1px solid var(--hl-border)}.exercise-number,.practice-num,.practice-header strong{display:inline-flex;align-items:center;padding:.24rem .65rem;border-radius:9999px;background:var(--hl-primary-light);color:var(--hl-primary);border:1px solid var(--hl-primary-border);font-size:.78rem;font-weight:800;letter-spacing:.02em}.exercise-marks,.practice-marks{display:inline-flex;align-items:center;padding:.22rem .6rem;border-radius:9999px;background:var(--hl-surface-muted);color:var(--hl-text-muted);border:1px solid var(--hl-border);font-size:.75rem;font-weight:700}.exercise-badge{display:inline-flex;align-items:center;gap:.35rem;padding:.2rem .6rem;border-radius:9999px;font-size:.74rem;font-weight:800;line-height:1.4;border:1px solid var(--hl-border)}.exercise-badge.tier-1,.badge-core{background:#f6f1f2;color:#b45309;border-color:#fef3c7}body.dark-mode .exercise-badge.tier-1,body.dark-mode .badge-core{background:#22c55e26;color:#fed7aa;border-color:#22c55e4d}.exercise-badge.tier-2,.badge-standard{background:#fffbeb;color:#b45309;border-color:#fde68a}body.dark-mode .exercise-badge.tier-2,body.dark-mode .badge-standard{background:#f59e0b26;color:#fcd34d;border-color:#f59e0b4d}.exercise-badge.tier-3,.badge-challenge{background:#fdf2f8;color:#be185d;border-color:#fbcfe8}body.dark-mode .exercise-badge.tier-3,body.dark-mode .badge-challenge{background:#db277726;color:#f472b6;border-color:#db27774d}.exercise-solve-toggle{margin-left:auto;display:inline-flex;align-items:center;gap:.45rem;font-size:.78rem;font-weight:700;color:var(--hl-text-muted);cursor:pointer;user-select:none;padding:.28rem .65rem;border-radius:9999px;background:var(--hl-surface-muted);border:1px solid var(--hl-border);transition:all .15s ease}.exercise-solve-toggle:hover{color:var(--hl-primary);border-color:var(--hl-primary-border);background:var(--hl-primary-light)}.solution-toggle-btn{display:inline-flex;align-items:center;justify-content:center;gap:.65rem;padding:.52rem 1.05rem;margin-top:.85rem;font-family:inherit;font-size:.84rem;font-weight:700;color:var(--hl-primary);background:var(--hl-primary-light);border:1px solid var(--hl-primary-border);border-radius:8px;cursor:pointer;transition:all .2s cubic-bezier(.16,1,.3,1);user-select:none}.solution-toggle-btn:hover{background:var(--hl-primary);color:#fff;border-color:var(--hl-primary);box-shadow:0 4px 12px #83184340;transform:translateY(-1px)}.solution-toggle-btn[aria-expanded=true]{background:var(--hl-primary);color:#fff;border-color:var(--hl-primary)}.solution-toggle-btn i{font-size:.75rem;transition:transform .2s ease}.solution-toggle-btn[aria-expanded=true] i{transform:rotate(180deg)}.practice-item .solution-content{display:none;min-width:0;margin-top:.85rem;padding:.95rem 1.15rem;border-radius:8px;background:var(--hl-surface-muted);border:1px solid var(--hl-border);border-left:3px solid var(--hl-primary);color:var(--hl-text-secondary);font-size:.94rem;line-height:1.7}.practice-item .solution-toggle-btn[aria-expanded=true]+.solution-content,.practice-item .solution-content.open{display:block}.exercise-solve-toggle input[type=checkbox]{accent-color:var(--hl-primary, #b45309);width:15px;height:15px;margin:0;cursor:pointer}.question-text,.exercise-stem{margin:.45rem 0 .75rem;color:var(--hl-text);font-size:.98rem;line-height:1.65}.solution-details{margin-top:.65rem;border:1px solid var(--hl-border);border-radius:12px;background:var(--hl-surface-muted);overflow:hidden;transition:all .2s ease}.solution-details>summary,.solution-toggle{display:flex;align-items:center;justify-content:space-between;gap:.75rem;min-height:40px;padding:.5rem .85rem;color:var(--hl-primary);cursor:pointer;font-size:.88rem;font-weight:800;line-height:1.4;list-style:none;user-select:none;transition:background-color .15s ease,color .15s ease}.solution-details>summary::-webkit-details-marker{display:none}.solution-details>summary:after{content:"\f078";font-family:"Font Awesome 6 Free";font-weight:900;font-size:.8rem;color:var(--hl-primary);transition:transform .2s ease}.solution-details[open]>summary:after{transform:rotate(180deg)}.solution-details>summary:hover,.solution-toggle:hover{background:var(--hl-primary-light)}.solution-details[open]>summary{border-bottom:1px solid var(--hl-border)}.solution-content{padding:.8rem 1rem;color:var(--hl-text-secondary);font-size:.94rem;line-height:1.65;background:var(--hl-surface)}.ib-mark-pill{display:inline-flex;align-items:center;justify-content:center;padding:.12rem .45rem;border-radius:6px;font-size:.74rem;font-weight:800;font-family:var(--font-sans);letter-spacing:.02em;margin:0 .2rem;vertical-align:middle}.ib-mark-m{background:#e0f2fe;color:#b8541a;border:1px solid #fed7aa}body.dark-mode .ib-mark-m{background:#0284c733;color:#fb923c;border-color:#0284c766}.ib-mark-a{background:#fef3c7;color:#b45309;border:1px solid #fef3c7}body.dark-mode .ib-mark-a{background:#22c55e33;color:#fed7aa;border-color:#22c55e66}.ib-mark-r{background:#f3e8ff;color:#7e22ce;border:1px solid #e9d5ff}body.dark-mode .ib-mark-r{background:#a855f733;color:#d8b4fe;border-color:#a855f766}.ib-mark-ag{background:#fef3c7;color:#b45309;border:1px solid #fde68a}body.dark-mode .ib-mark-ag{background:#f59e0b33;color:#fcd34d;border-color:#f59e0b66}.formula-card{position:relative;margin:.75rem 0;padding:1.05rem 1.2rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);transition:all .2s ease}.formula-card:hover{transform:translateY(-2px);border-color:var(--hl-primary-border);box-shadow:var(--hl-shadow-md)}.formula-card h4{margin:0 0 .5rem;font-family:var(--font-display, "Outfit", sans-serif);font-size:1.05rem;font-weight:800;color:var(--hl-text)}.formula-card p{color:var(--hl-text-secondary);font-size:.92rem;line-height:1.55;margin:.35rem 0 0}.btn-copy-formula{position:absolute;top:.85rem;right:.85rem;background:var(--hl-surface-muted);border:1px solid var(--hl-border);color:var(--hl-text-secondary);font-size:.74rem;font-weight:700;padding:.3rem .6rem;border-radius:6px;cursor:pointer;display:inline-flex;align-items:center;gap:.35rem;transition:all .15s ease}.btn-copy-formula:hover{background:var(--hl-primary-light);border-color:var(--hl-primary-border);color:var(--hl-primary)}.pitfall-card{margin:.75rem 0;padding:1.05rem 1.2rem;border-radius:14px;border:1px solid #fed7aa;border-left:5px solid #f59e0b;background:#fffbeb;box-shadow:0 2px 8px #f59e0b14;transition:all .2s ease}body.dark-mode .pitfall-card{border-color:#f59e0b59;border-left-color:#fbbf24;background:#f59e0b14}.pitfall-card h4{margin:0 0 .45rem;color:#b45309;font-family:var(--font-display, "Outfit", sans-serif);font-size:1.05rem;font-weight:800;display:flex;align-items:center;gap:.45rem}body.dark-mode .pitfall-card h4{color:#fcd34d}.pitfall-card h4:before{content:"\26a0\fe0f";font-size:1rem}.pitfall-card p{margin:0;color:var(--hl-text-secondary);font-size:.92rem;line-height:1.6}.quiz-card,.quiz-question-card{margin-bottom:.85rem;padding:1.05rem 1.25rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);transition:border-color .2s ease,box-shadow .2s ease}.quiz-card:hover,.quiz-question-card:hover{border-color:var(--hl-border-hover);box-shadow:var(--hl-shadow-sm)}.quiz-card-header,.quiz-question-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:.55rem}.quiz-badge{display:inline-flex;align-items:center;padding:.2rem .55rem;border-radius:9999px;background:var(--hl-primary-light);color:var(--hl-primary);font-size:.74rem;font-weight:800}.quiz-question,.quiz-stem{font-size:1rem;font-weight:700;color:var(--hl-text);margin:0 0 .75rem;line-height:1.55}.quiz-options,.quiz-options-group{display:grid;gap:.5rem}.quiz-option,.quiz-option-label{display:flex;align-items:center;gap:.75rem;width:100%;padding:.65rem .95rem;border:1px solid var(--hl-border);border-radius:10px;background:var(--hl-surface-muted);color:var(--hl-text-secondary);font-size:.92rem;text-align:left;cursor:pointer;transition:all .18s ease;user-select:none}.quiz-option:hover,.quiz-option-label:hover{border-color:var(--hl-primary-border);background:var(--hl-primary-light);color:var(--hl-text);transform:translate(3px)}.quiz-option.active-selected,.quiz-option-label.active-selected{border-color:var(--hl-primary)!important;background:var(--hl-primary-light)!important;color:var(--hl-text)!important;box-shadow:0 0 0 2px var(--hl-primary-glow)}.quiz-option input[type=radio],.quiz-option-label input[type=radio]{accent-color:var(--hl-primary);width:1.15rem;height:1.15rem;margin:0;cursor:pointer;flex-shrink:0}.opt-letter{display:inline-flex;align-items:center;justify-content:center;width:28px;height:28px;border-radius:50%;border:1px solid var(--hl-border);background:var(--hl-surface);color:var(--hl-text);font-weight:800;font-size:.82rem;flex-shrink:0;transition:all .16s ease}.quiz-option:hover .opt-letter,.quiz-option-label:hover .opt-letter,.quiz-option.active-selected .opt-letter,.quiz-option-label.active-selected .opt-letter{border-color:var(--hl-primary);background:var(--hl-primary);color:#fff}.opt-text,.quiz-option-text{flex-grow:1;color:var(--hl-text);font-size:.96rem;line-height:1.5}.quiz-option.correct,.quiz-option-label.correct{border-color:#b45309!important;background:#22c55e1f!important;color:#b45309!important}body.dark-mode .quiz-option.correct,body.dark-mode .quiz-option-label.correct{color:#fed7aa!important}.quiz-option.correct .opt-letter,.quiz-option-label.correct .opt-letter{background:#b45309!important;border-color:#b45309!important;color:#fff!important}.quiz-option.wrong,.quiz-option-label.wrong{border-color:#ef4444!important;background:#ef44441f!important;color:#b91c1c!important}body.dark-mode .quiz-option.wrong,body.dark-mode .quiz-option-label.wrong{color:#fca5a5!important}.quiz-option.wrong .opt-letter,.quiz-option-label.wrong .opt-letter{background:#ef4444!important;border-color:#ef4444!important;color:#fff!important}.quiz-feedback,.quiz-feedback-box{display:none;margin-top:1rem;padding:.85rem 1.15rem;border-radius:12px;font-size:.92rem;line-height:1.6}.quiz-feedback.show{display:block}.quiz-feedback.correct{background:#22c55e1a;color:#b45309;border-left:4px solid #b45309}body.dark-mode .quiz-feedback.correct{color:#fed7aa}.quiz-feedback.wrong{background:#ef44441a;color:#991b1b;border-left:4px solid #ef4444}body.dark-mode .quiz-feedback.wrong{color:#fca5a5}#btn-submit-quiz{padding:.85rem 2rem;font-family:var(--font-display, "Outfit", sans-serif);font-size:1rem;font-weight:800;border-radius:12px;background:linear-gradient(135deg,#831843,#b8541a);color:#fff;border:none;cursor:pointer;box-shadow:0 4px 14px #5c1d3d4d;transition:all .2s cubic-bezier(.16,1,.3,1);display:inline-flex;align-items:center;gap:.5rem}#btn-submit-quiz:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 6px 20px #5c1d3d66}#btn-submit-quiz:active:not(:disabled){transform:translateY(0)}#btn-submit-quiz:disabled{opacity:.65;cursor:not-allowed}#quiz-score-display{padding:.85rem 1.5rem;border-radius:12px;background:var(--hl-primary-light);border:1px solid var(--hl-primary-border);color:var(--hl-primary);font-family:var(--font-display, "Outfit", sans-serif);font-size:1.25rem;font-weight:800;display:inline-block}.exam-q-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:.85rem;flex-wrap:wrap;gap:.5rem}.exam-marks-total{font-size:.82rem;font-weight:800;color:var(--hl-primary);background:var(--hl-primary-light);padding:.25rem .65rem;border-radius:9999px;border:1px solid var(--hl-primary-border)}.related-guides{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:1rem;margin-top:2.5rem}.related-guides a{display:flex;flex-direction:column;padding:1.15rem 1.35rem;border:1px solid var(--hl-border);border-radius:14px;background:var(--hl-surface);text-decoration:none;transition:all .2s ease;box-shadow:var(--hl-shadow-xs)}.related-guides a:hover{transform:translateY(-3px);border-color:var(--hl-primary-border);box-shadow:var(--hl-shadow-md)}.related-guides a span{font-size:.74rem;font-weight:800;text-transform:uppercase;letter-spacing:.06em;color:var(--hl-primary);margin-bottom:.35rem}.related-guides a strong{font-family:var(--font-display, "Outfit", sans-serif);font-size:1.05rem;color:var(--hl-text);font-weight:800;line-height:1.35}.hl-toast{position:fixed;bottom:2rem;right:2rem;z-index:1000;padding:.75rem 1.25rem;background:#111827;color:#fff;border-radius:12px;font-size:.88rem;font-weight:700;box-shadow:var(--hl-shadow-lg);display:flex;align-items:center;gap:.5rem;animation:toastFadeIn .25s cubic-bezier(.16,1,.3,1)}@keyframes toastFadeIn{0%{opacity:0;transform:translateY(12px) scale(.95)}to{opacity:1;transform:translateY(0) scale(1)}}@media(max-width:768px){.ib-nav-container{padding:.5rem .85rem}.ib-hero-title{font-size:clamp(1.6rem,6vw,2.2rem)}.study-tabs-nav{top:3.3rem;padding:.25rem}.study-tab-btn{padding:.5rem .85rem;font-size:.82rem}.concept-card,.example-card,.exercise-card,.quiz-card{padding:1rem 1.15rem}.practice-controls-bar{flex-direction:column;align-items:flex-start}}.lesson-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1.15rem;margin-top:1.25rem}@media(max-width:768px){.lesson-grid{grid-template-columns:1fr}}.lesson-card{display:flex;min-width:0;flex-direction:column;align-items:flex-start;gap:.65rem;padding:1.35rem 1.45rem;border:1px solid var(--hl-border);border-left:4px solid var(--hl-primary);border-radius:16px;color:var(--hl-text);background:var(--hl-surface);text-decoration:none;box-shadow:var(--hl-shadow-xs);transition:all .22s cubic-bezier(.16,1,.3,1);position:relative;overflow:hidden}.lesson-card:hover,.lesson-card:focus-visible{border-color:var(--hl-primary-border);border-left-color:var(--hl-primary);background:var(--hl-surface);transform:translateY(-4px);box-shadow:var(--hl-shadow-lg),var(--hl-shadow-glow)}.lesson-card-code{display:inline-flex;align-items:center;gap:.35rem;padding:.2rem .55rem;border-radius:6px;background:var(--hl-primary-light);color:var(--hl-primary);font-size:.76rem;font-weight:800;letter-spacing:.04em}.lesson-card-title{font-family:var(--font-display, "Outfit", sans-serif);font-size:1.18rem;font-weight:800;color:var(--hl-text);line-height:1.3;margin:0;transition:color .15s ease}.lesson-card:hover .lesson-card-title{color:var(--hl-primary)}.lesson-card-desc{color:var(--hl-text-secondary);font-size:.92rem;line-height:1.6;margin:0;flex-grow:1}.lesson-card-link{margin-top:auto;padding-top:.45rem;color:var(--hl-primary);font-size:.86rem;font-weight:800;display:inline-flex;align-items:center;gap:.4rem;transition:gap .2s ease}.lesson-card:hover .lesson-card-link{gap:.65rem}.coverage-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:.85rem 1.25rem;margin:1.25rem 0 0;padding:0;list-style:none}@media(max-width:820px){.coverage-list{grid-template-columns:1fr}}.coverage-list li{display:grid;grid-template-columns:4.8rem minmax(0,1fr);align-items:start;gap:.75rem;padding:.95rem 1.15rem;border:1px solid var(--hl-border);border-radius:12px;background:var(--hl-surface);box-shadow:var(--hl-shadow-xs);color:var(--hl-text-secondary);font-size:.92rem;line-height:1.6;transition:border-color .15s ease}.coverage-list li:hover{border-color:var(--hl-primary-border)}.coverage-code{color:var(--hl-primary);font-variant-numeric:tabular-nums;font-weight:800;font-size:.82rem;background:var(--hl-primary-light);padding:.2rem .45rem;border-radius:6px;text-align:center;width:fit-content}.section-badge{display:inline-flex;align-items:center;gap:.4rem;padding:.25rem .7rem;border-radius:9999px;font-size:.74rem;font-weight:800;text-transform:uppercase;letter-spacing:.06em;background:var(--hl-primary-light);color:var(--hl-primary);border:1px solid var(--hl-primary-border);margin-bottom:.45rem}.section-title{font-family:var(--font-display, "Outfit", sans-serif);font-size:1.65rem;font-weight:800;color:var(--hl-text);letter-spacing:-.02em;margin:0 0 .45rem}.section-desc{font-size:.98rem;color:var(--hl-text-secondary);line-height:1.65;margin:0 0 1.25rem}
