:root{--sidebar-w: 310px;--bg: #F8F6F1;--bg-card: #FFFFFF;--sidebar-bg: #16181F;--sidebar-hover: #1E2130;--sidebar-active: #252838;--sidebar-text: #B8BCD0;--sidebar-text-dim: #60637A;--sidebar-border: #252838;--text: #1E1E1E;--text-muted: #767676;--text-light: #A0A0A0;--border: #E8E5DC;--shadow: 0 1px 3px rgba(0,0,0,.06), 0 4px 12px rgba(0,0,0,.06);--shadow-md: 0 4px 16px rgba(0,0,0,.1);--radius: 8px;--radius-lg: 12px;--font-body: "Inter", system-ui, -apple-system, sans-serif;--font-heading: "Lora", Georgia, "Times New Roman", serif;--transition: .2s ease}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{font-family:var(--font-body);font-size:16px;line-height:1.65;color:var(--text);background:var(--bg);overflow-x:hidden}a{color:inherit;text-decoration:none}img{max-width:100%;display:block}.app{display:flex;min-height:100vh}.sidebar{width:var(--sidebar-w);min-height:100vh;background:var(--sidebar-bg);display:flex;flex-direction:column;position:fixed;top:0;left:0;bottom:0;z-index:100;overflow-y:auto;overflow-x:hidden;transition:transform var(--transition);scrollbar-width:thin;scrollbar-color:#2E3248 transparent}.sidebar::-webkit-scrollbar{width:4px}.sidebar::-webkit-scrollbar-track{background:transparent}.sidebar::-webkit-scrollbar-thumb{background:#2e3248;border-radius:4px}.sidebar-header{padding:28px 20px 20px;border-bottom:1px solid var(--sidebar-border)}.course-badge{display:inline-block;font-family:var(--font-body);font-size:11px;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--sidebar-text-dim);border:1px solid #2E3248;border-radius:4px;padding:3px 8px;margin-bottom:10px;transition:color var(--transition),border-color var(--transition)}.course-badge:hover{color:var(--sidebar-text);border-color:#40455e}.course-institution{font-size:10px;letter-spacing:.06em;text-transform:uppercase;color:var(--sidebar-text-dim);margin-bottom:6px}.course-title{font-family:var(--font-heading);font-size:15px;font-weight:600;color:#e8eaf0;line-height:1.3;margin-bottom:2px}.course-subtitle{font-size:12px;color:var(--sidebar-text-dim);font-style:italic}.sidebar-nav{padding:12px 0 24px}.nav-module{margin-bottom:4px}.nav-module-header{display:flex;align-items:center;gap:10px;padding:11px 20px;cursor:pointer;-webkit-user-select:none;user-select:none;transition:background var(--transition);border-left:3px solid transparent;position:relative}.nav-module-header:hover{background:var(--sidebar-hover)}.nav-module-header.active-module{border-left-color:var(--module-color, #888)}.nav-module-icon{font-size:16px;width:20px;text-align:center;flex-shrink:0}.nav-module-info{flex:1;min-width:0}.nav-module-number{font-size:11px;font-weight:600;letter-spacing:.07em;text-transform:uppercase;color:#8890b0;margin-bottom:2px}.nav-module-title{font-size:14px;font-weight:600;color:#d8dcf0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;line-height:1.3}.nav-module-chevron{font-size:11px;color:#8890b0;transition:transform var(--transition);flex-shrink:0}.nav-module.open .nav-module-chevron{transform:rotate(90deg)}.nav-lessons{display:none;padding:2px 0 6px}.nav-module.open .nav-lessons{display:block}.nav-lesson{display:flex;align-items:center;gap:8px;padding:8px 20px 8px 40px;cursor:pointer;transition:background var(--transition);border-left:3px solid transparent;margin-left:0}.nav-lesson:hover{background:var(--sidebar-hover)}.nav-lesson.active{background:var(--sidebar-active);border-left-color:var(--module-color, #888)}.nav-lesson-dot{width:6px;height:6px;border-radius:50%;border:1.5px solid var(--sidebar-text-dim);flex-shrink:0;transition:background var(--transition),border-color var(--transition)}.nav-lesson.has-content .nav-lesson-dot{background:var(--module-color, #888);border-color:var(--module-color, #888)}.nav-lesson.active .nav-lesson-dot{background:var(--module-color, #888);border-color:var(--module-color, #888);box-shadow:0 0 0 2px #ffffff1a}.nav-lesson-id{font-size:11px;font-weight:600;color:#8890b0;min-width:28px}.nav-lesson-title{font-size:13px;color:#c4c8e0;line-height:1.35}.nav-lesson.active .nav-lesson-title{color:#f0f2ff}.nav-lesson:hover .nav-lesson-title{color:#e0e4f8}.nav-module-progress{width:100%;height:2px;background:#2a2d3e;border-radius:1px;margin-top:4px;overflow:hidden}.nav-module-progress-fill{height:100%;border-radius:1px;background:var(--module-color, #888);transition:width .4s ease}.sidebar-toggle{display:none;position:fixed;top:16px;left:16px;z-index:200;width:38px;height:38px;background:var(--sidebar-bg);border:1px solid #2E3248;border-radius:var(--radius);cursor:pointer;flex-direction:column;align-items:center;justify-content:center;gap:4px;padding:0}.sidebar-toggle span{display:block;width:18px;height:2px;background:var(--sidebar-text);border-radius:2px;transition:var(--transition)}.sidebar-overlay{display:none;position:fixed;top:0;right:0;bottom:0;left:0;background:#00000080;z-index:90}.content{margin-left:var(--sidebar-w);flex:1;min-height:100vh;display:flex;flex-direction:column}.home-page{max-width:860px;margin:0 auto;padding:56px 40px 80px;width:100%}.home-hero{margin-bottom:48px;padding-bottom:40px;border-bottom:1px solid var(--border)}.home-hero-tag{display:inline-flex;align-items:center;gap:6px;font-size:11px;font-weight:600;letter-spacing:.1em;text-transform:uppercase;color:var(--text-muted);margin-bottom:16px}.home-hero h1{font-family:var(--font-heading);font-size:38px;font-weight:700;line-height:1.2;margin-bottom:12px;color:var(--text)}.home-hero p{font-size:17px;color:var(--text-muted);max-width:560px;line-height:1.7}.home-modules-title{font-size:11px;font-weight:600;letter-spacing:.1em;text-transform:uppercase;color:var(--text-muted);margin-bottom:20px}.home-modules-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:16px}.module-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);padding:20px 22px;cursor:pointer;transition:box-shadow var(--transition),transform var(--transition),border-color var(--transition);position:relative;overflow:hidden}.module-card:before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:var(--module-color)}.module-card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px);border-color:#0000001a}.module-card-top{display:flex;align-items:flex-start;justify-content:space-between;margin-bottom:10px}.module-card-icon{font-size:22px;line-height:1}.module-card-number{font-size:10px;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--text-muted);padding:3px 8px;background:var(--bg);border-radius:4px}.module-card h3{font-family:var(--font-heading);font-size:16px;font-weight:600;color:var(--text);margin-bottom:14px;line-height:1.3}.module-card-lessons{display:flex;flex-wrap:wrap;gap:5px}.module-card-lesson-chip{font-size:10px;color:var(--text-muted);background:var(--bg);border:1px solid var(--border);border-radius:4px;padding:2px 7px;transition:background var(--transition),color var(--transition)}.module-card-lesson-chip.has-content{background:var(--module-color-light, #f0f0f0);color:var(--module-color, #333);border-color:transparent;font-weight:500}.module-card-progress{margin-top:14px;display:flex;align-items:center;gap:10px}.module-card-progress-bar{flex:1;height:3px;background:var(--border);border-radius:2px;overflow:hidden}.module-card-progress-fill{height:100%;background:var(--module-color);border-radius:2px}.module-card-progress-text{font-size:10px;color:var(--text-light);white-space:nowrap}.lesson-page{display:flex;flex-direction:column;min-height:100vh}.lesson-header{background:var(--bg-card);border-bottom:1px solid var(--border);padding:32px 40px 28px;position:relative}.lesson-header:before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:var(--module-color, #888)}.lesson-breadcrumb{display:flex;align-items:center;gap:6px;font-size:12px;color:var(--text-muted);margin-bottom:12px}.lesson-breadcrumb a{transition:color var(--transition)}.lesson-breadcrumb a:hover{color:var(--text)}.lesson-breadcrumb-sep{color:var(--border)}.lesson-breadcrumb-current{color:var(--text-muted)}.lesson-module-badge{font-size:11px;font-weight:600;letter-spacing:.06em;text-transform:uppercase;color:#fff;background:var(--module-color, #888);border-radius:4px;padding:3px 9px}.lesson-id-badge{font-size:11px;font-weight:600;color:var(--text-muted);background:var(--bg);border:1px solid var(--border);border-radius:4px;padding:3px 9px}.lesson-header-row{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;margin-bottom:10px}.lesson-header-meta{display:flex;align-items:center;gap:8px}.view-toggle{display:flex;background:var(--bg);border:1px solid var(--border);border-radius:8px;padding:3px;gap:2px}.view-toggle-btn{display:flex;align-items:center;gap:6px;padding:6px 12px;border:none;background:transparent;border-radius:6px;font-family:var(--font-body);font-size:12px;font-weight:500;color:var(--text-muted);cursor:pointer;transition:background var(--transition),color var(--transition);white-space:nowrap}.view-toggle-btn:hover{background:var(--bg-card);color:var(--text)}.view-toggle-btn.active{background:var(--bg-card);color:var(--module-color, var(--text));box-shadow:0 1px 3px #00000014}.view-toggle-btn svg{flex-shrink:0;opacity:.7}.view-toggle-btn.active svg{opacity:1}.lesson-body.is-transcript p,.lesson-body.is-transcript li{font-size:17px;line-height:1.9;color:#444}.lesson-body.is-transcript h2,.lesson-body.is-transcript h3{display:none}.lesson-header h1{font-family:var(--font-heading);font-size:28px;font-weight:700;line-height:1.25;color:var(--text);max-width:720px}.speak-btn{display:inline-flex;align-items:center;justify-content:center;margin-left:7px;padding:3px 5px;background:transparent;border:1px solid var(--border);border-radius:5px;color:var(--text-light);cursor:pointer;vertical-align:middle;line-height:1;transition:background var(--transition),color var(--transition),border-color var(--transition),transform 80ms ease}.speak-btn:hover{background:var(--module-color-light, #f0f0f0);color:var(--module-color, #555);border-color:var(--module-color, #aaa)}.speak-btn:active{transform:scale(.92)}.speak-btn.speaking{color:var(--module-color, #555);border-color:var(--module-color, #aaa);animation:pulse-speak .6s ease infinite alternate}@keyframes pulse-speak{0%{opacity:1}to{opacity:.45}}.lesson-empty{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:80px 40px;color:var(--text-muted)}.lesson-empty-icon{font-size:40px;margin-bottom:16px;opacity:.4}.lesson-empty h2{font-family:var(--font-heading);font-size:20px;font-weight:600;color:var(--text);margin-bottom:8px;opacity:.6}.lesson-empty p{font-size:14px;max-width:320px;line-height:1.6}.lesson-body{max-width:760px;padding:40px 40px 60px}.lesson-body h1{display:none}.lesson-body h2{font-family:var(--font-heading);font-size:26px;font-weight:700;color:var(--text);margin:40px 0 16px;padding-bottom:10px;border-bottom:2px solid var(--border)}.lesson-body h3{font-family:var(--font-heading);font-size:20px;font-weight:600;color:var(--text);margin:32px 0 12px}.lesson-body h4{font-size:15px;font-weight:600;text-transform:uppercase;letter-spacing:.06em;color:var(--text-muted);margin:26px 0 10px}.lesson-body p{font-size:17px;margin-bottom:18px;color:#333;line-height:1.8}.lesson-body ul,.lesson-body ol{margin:0 0 18px;padding-left:26px}.lesson-body li{font-size:17px;margin-bottom:8px;line-height:1.75;color:#333}.lesson-body li::marker{color:var(--module-color, #888)}.lesson-body strong{font-weight:600;color:var(--text)}.lesson-body em{font-style:italic;color:var(--text)}.lesson-body blockquote{border-left:4px solid var(--module-color, #888);background:var(--module-color-light, #f9f9f9);padding:14px 18px;border-radius:0 var(--radius) var(--radius) 0;margin:24px 0;font-style:italic;color:var(--text-muted)}.lesson-body blockquote p{margin-bottom:0;color:inherit}.lesson-body table{width:100%;border-collapse:collapse;margin:24px 0;font-size:15px}.lesson-body th{background:var(--bg);font-weight:600;text-align:left;padding:11px 16px;border-bottom:2px solid var(--border);color:var(--text)}.lesson-body td{padding:10px 16px;border-bottom:1px solid var(--border);vertical-align:top}.lesson-body tr:last-child td{border-bottom:none}.lesson-body hr{border:none;border-top:1px solid var(--border);margin:32px 0}.lesson-body code{font-family:SF Mono,Fira Code,monospace;font-size:13px;background:#f0ede6;border:1px solid var(--border);padding:1px 6px;border-radius:4px}.lesson-body mark{background:var(--module-color-light, #fffbcc);padding:1px 4px;border-radius:3px}.lesson-media{padding:0 40px 40px;max-width:760px}.lesson-media-section{margin-bottom:32px}.lesson-media-section h3{font-size:11px;font-weight:600;letter-spacing:.1em;text-transform:uppercase;color:var(--text-muted);margin-bottom:12px}.lesson-video-placeholder,.lesson-slides-placeholder{background:var(--bg-card);border:2px dashed var(--border);border-radius:var(--radius-lg);padding:36px;text-align:center;color:var(--text-light);font-size:14px}.lesson-nav{margin-top:auto;border-top:1px solid var(--border);display:flex;background:var(--bg-card)}.lesson-nav-btn{flex:1;display:flex;align-items:center;padding:20px 28px;gap:12px;cursor:pointer;transition:background var(--transition);border:none;background:transparent;text-align:left;font-family:inherit;color:var(--text)}.lesson-nav-btn:hover{background:var(--bg)}.lesson-nav-btn:disabled{opacity:.3;cursor:default}.lesson-nav-btn:disabled:hover{background:transparent}.lesson-nav-btn+.lesson-nav-btn{border-left:1px solid var(--border);justify-content:flex-end;text-align:right}.lesson-nav-btn .nav-btn-label{font-size:10px;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--text-muted);display:block;margin-bottom:2px}.lesson-nav-btn .nav-btn-title{font-size:14px;font-weight:500;line-height:1.3}.lesson-nav-btn .nav-btn-arrow{font-size:20px;color:var(--text-muted);flex-shrink:0}@media (max-width: 768px){.sidebar{transform:translate(-100%)}.sidebar.open{transform:translate(0);box-shadow:var(--shadow-md)}.sidebar-overlay.visible{display:block}.sidebar-toggle{display:flex}.content{margin-left:0}.lesson-header{padding:64px 20px 20px}.lesson-body{padding:28px 20px 48px}.lesson-media{padding:0 20px 28px}.home-page{padding:72px 20px 60px}.home-hero h1{font-size:28px}.home-modules-grid{grid-template-columns:1fr}.lesson-nav-btn{padding:16px 20px}}@keyframes fadeIn{0%{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}.fade-in{animation:fadeIn .25s ease forwards}::-webkit-scrollbar{width:6px;height:6px}::-webkit-scrollbar-track{background:transparent}::-webkit-scrollbar-thumb{background:#d0cdc6;border-radius:3px}.selection-popup{position:fixed;z-index:2000;background:#1e2130;border:1px solid rgba(255,255,255,.12);border-radius:12px;padding:12px 14px;max-width:300px;min-width:180px;box-shadow:0 8px 32px #00000073;display:none;pointer-events:all}.selection-popup.visible{display:block;animation:fadeIn .15s ease forwards}.selection-popup-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px;gap:8px}.selection-popup-label{font-size:11px;font-weight:600;letter-spacing:.06em;text-transform:uppercase;color:#6b7199}.selection-popup-actions{display:flex;align-items:center;gap:4px;margin-left:auto}.selection-speak-btn{background:#ffffff14;border:1px solid rgba(255,255,255,.1);border-radius:6px;color:#9aa0c0;cursor:pointer;padding:4px 8px;display:flex;align-items:center;gap:5px;font-size:11px;font-family:var(--font-body);transition:background var(--transition),color var(--transition)}.selection-speak-btn:hover{background:#ffffff29;color:#fff}.selection-speak-btn.speaking{color:#7c9cff}.selection-popup-close{background:none;border:none;color:#4a4e6a;cursor:pointer;font-size:14px;padding:2px 4px;line-height:1;border-radius:4px;transition:color var(--transition)}.selection-popup-close:hover{color:#9aa0c0}.selection-popup-divider{height:1px;background:#ffffff12;margin:8px 0}.selection-popup-translation{color:#d8daf0;font-size:14px;line-height:1.6;word-break:break-word}.selection-popup-loading{color:#4a4e6a;font-style:italic;font-size:13px}.selection-popup-error{color:#6b4e4e;font-size:12px}::-webkit-scrollbar-thumb:hover{background:#b0ada6}