:root{--bg-primary: #ffffff;--bg-secondary: #f8fafc;--bg-tertiary: #f1f5f9;--border-color: #e2e8f0;--text-primary: #0f172a;--text-secondary: #334155;--text-light: #64748b;--primary: #2563eb;--primary-hover: #1d4ed8;--primary-light: #eff6ff;--primary-border: #bfdbfe;--success: #10b981;--success-light: #ecfdf5;--success-border: #a7f3d0;--font-sans: "Inter", system-ui, -apple-system, sans-serif;--sidebar-width: 320px;--panel-width: 300px;--header-height: 64px;--transition: all .2s cubic-bezier(.4, 0, .2, 1);--shadow-sm: 0 1px 3px rgba(0,0,0,.05);--shadow-md: 0 4px 6px -1px rgba(0, 0, 0, .05), 0 2px 4px -1px rgba(0, 0, 0, .03)}*{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-sans);background-color:var(--bg-primary);color:var(--text-primary);overflow:hidden;height:100vh;-webkit-font-smoothing:antialiased}.app-container{display:grid;grid-template-columns:var(--sidebar-width) 1fr var(--panel-width);height:100vh;width:100vw;background-color:var(--bg-primary)}.sidebar{background-color:var(--bg-secondary);border-right:1px solid var(--border-color);display:flex;flex-direction:column;height:100vh;overflow-y:auto}.sidebar-header{padding:24px;border-bottom:1px solid var(--border-color)}.logo{font-size:20px;font-weight:800;letter-spacing:-.5px;color:var(--text-primary)}.logo-accent{color:var(--primary)}.logo-sub{font-size:11px;font-weight:600;color:var(--text-light);letter-spacing:1.5px;margin-top:4px;text-transform:uppercase}.search-box{margin:16px 24px;position:relative}.search-box input{width:100%;padding:10px 36px 10px 14px;border-radius:8px;border:1px solid var(--border-color);background-color:var(--bg-primary);font-family:var(--font-sans);font-size:14px;color:var(--text-primary);transition:var(--transition)}.search-box input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px #2563eb1a}.search-box .search-icon{position:absolute;right:12px;top:50%;transform:translateY(-50%);font-size:18px;color:var(--text-light);pointer-events:none;-webkit-user-select:none;user-select:none}.progress-section{background-color:var(--bg-primary);border:1px solid var(--border-color);border-radius:12px;padding:16px;margin:0 24px 20px;box-shadow:var(--shadow-sm)}.progress-info{display:flex;justify-content:space-between;font-size:13px;font-weight:600;color:var(--text-secondary);margin-bottom:8px}.progress-bar-container{width:100%;height:6px;background-color:var(--bg-tertiary);border-radius:3px;overflow:hidden;margin-bottom:6px}.progress-bar-fill{height:100%;width:0%;background-color:var(--primary);border-radius:3px;transition:width .4s ease-out}.progress-stats{font-size:11px;color:var(--text-light)}.modules-navigation{padding:0 16px 24px;flex:1}.module-group{margin-bottom:12px}.module-title{display:flex;justify-content:space-between;align-items:center;width:100%;padding:12px;border-radius:8px;background:none;border:none;text-align:left;font-family:var(--font-sans);font-size:14px;font-weight:700;color:var(--text-primary);cursor:pointer;transition:var(--transition)}.module-title:hover{background-color:var(--bg-tertiary)}.module-icon-chevron{font-size:18px;color:var(--text-light);transition:transform .2s;-webkit-user-select:none;user-select:none}.module-group.active .module-icon-chevron{transform:rotate(90deg)}.module-lessons{display:none;list-style:none;padding-left:12px;margin-top:4px}.module-group.active .module-lessons{display:block}.lesson-item{display:flex;align-items:center;padding:8px 12px;margin:2px 0;border-radius:6px;font-size:13px;font-weight:500;color:var(--text-secondary);cursor:pointer;transition:var(--transition);position:relative}.lesson-item:hover{background-color:var(--bg-tertiary);color:var(--text-primary)}.lesson-item.active{background-color:var(--primary-light);color:var(--primary);font-weight:600}.status-icon{font-size:16px;color:var(--text-light);margin-right:8px;flex-shrink:0;transition:var(--transition);-webkit-user-select:none;user-select:none}.lesson-item.completed .status-icon{color:var(--success)}.lesson-item.active .status-icon{color:var(--primary)}.main-content{display:flex;flex-direction:column;height:100vh;overflow:hidden;background-color:var(--bg-primary);border-right:1px solid var(--border-color)}.content-header{height:var(--header-height);padding:0 32px;border-bottom:1px solid var(--border-color);display:flex;justify-content:space-between;align-items:center;flex-shrink:0;background-color:var(--bg-primary)}.breadcrumbs{font-size:13px;font-weight:600;color:var(--text-light);display:flex;align-items:center;gap:4px;flex-wrap:wrap}.breadcrumbs .active{color:var(--text-primary)}.breadcrumb-separator{font-size:16px;color:var(--text-light);-webkit-user-select:none;user-select:none}.btn-complete{display:inline-flex;align-items:center;gap:8px;padding:8px 14px;border-radius:8px;background-color:var(--bg-primary);border:1px solid var(--border-color);font-family:var(--font-sans);font-size:13px;font-weight:600;color:var(--text-secondary);cursor:pointer;transition:var(--transition)}.btn-complete:hover{border-color:var(--primary-border);color:var(--primary);background-color:var(--primary-light)}.btn-complete.active{background-color:var(--success-light);border-color:var(--success-border);color:var(--success)}.btn-complete .checkbox-icon{font-size:18px;color:var(--text-light);transition:var(--transition);-webkit-user-select:none;user-select:none}.btn-complete.active .checkbox-icon{color:var(--success)}.reader-body{flex:1;overflow-y:auto;padding:40px 64px;line-height:1.65;color:var(--text-secondary);max-width:900px;margin:0 auto;width:100%}.reader-body h1{font-size:32px;font-weight:800;color:var(--text-primary);letter-spacing:-.75px;margin-bottom:24px;line-height:1.25}.reader-body h2{font-size:22px;font-weight:700;color:var(--text-primary);letter-spacing:-.5px;margin-top:36px;margin-bottom:16px;padding-bottom:8px;border-bottom:1px solid var(--border-color)}.reader-body h3{font-size:17px;font-weight:700;color:var(--text-primary);margin-top:24px;margin-bottom:12px}.reader-body p{margin-bottom:16px}.reader-body ul,.reader-body ol{margin-bottom:20px;padding-left:24px}.reader-body li{margin-bottom:8px}.reader-body pre{margin:20px 0;border-radius:8px!important;box-shadow:var(--shadow-sm);background-color:var(--bg-secondary)!important;border:1px solid var(--border-color)}.reader-body code:not(pre code){background-color:var(--bg-tertiary);color:var(--text-primary);padding:2px 6px;border-radius:4px;font-size:85%;font-family:monospace}.reader-body table{width:100%;border-collapse:collapse;margin:24px 0;font-size:14px}.reader-body th,.reader-body td{padding:12px;border:1px solid var(--border-color);text-align:left}.reader-body th{background-color:var(--bg-secondary);font-weight:700;color:var(--text-primary)}.reader-body tr:nth-child(2n){background-color:var(--bg-secondary)}.reader-body blockquote{padding:16px 20px;margin:24px 0;border-left:4px solid var(--border-color);background-color:var(--bg-secondary);border-radius:0 8px 8px 0}.reader-body blockquote p:last-child{margin-bottom:0}.reader-body blockquote.note{border-left-color:var(--primary);background-color:var(--primary-light)}.reader-body blockquote.important,.reader-body blockquote.warning{border-left-color:#f59e0b;background-color:#fffbeb}.reader-body details{margin:24px 0;border:1px solid var(--border-color);background-color:var(--bg-secondary);border-radius:10px;overflow:hidden;box-shadow:var(--shadow-sm);transition:border-color .2s ease,box-shadow .2s ease}.reader-body details:hover{border-color:var(--primary-border);box-shadow:0 4px 12px #2563eb0d}.reader-body details[open]{border-color:var(--primary-border);box-shadow:0 4px 16px #2563eb14}.reader-body details summary{padding:16px 20px;font-weight:600;color:var(--text-primary);background-color:var(--bg-secondary);cursor:pointer;-webkit-user-select:none;user-select:none;display:flex;align-items:center;gap:8px;list-style:none;outline:none;transition:background-color .2s ease,color .2s ease}.reader-body details summary::-webkit-details-marker{display:none}.reader-body details summary:before{font-family:Material Icons;content:"";font-size:18px;color:var(--text-light);transition:transform .2s ease;display:inline-block}.reader-body details[open] summary:before{transform:rotate(90deg);color:var(--primary)}.reader-body details summary:hover{background-color:var(--primary-light);color:var(--primary)}.reader-body details summary:hover:before{color:var(--primary)}.reader-body details .example-content{padding:20px;border-top:1px solid var(--border-color);background-color:var(--bg-primary);line-height:1.7}.loader{display:flex;justify-content:center;align-items:center;height:200px;font-weight:500;color:var(--text-light)}.content-footer{height:72px;border-top:1px solid var(--border-color);display:flex;justify-content:space-between;align-items:center;padding:0 32px;flex-shrink:0;background-color:var(--bg-primary)}.btn-nav{display:inline-flex;align-items:center;gap:8px;padding:10px 18px;border-radius:8px;border:1px solid var(--border-color);background-color:var(--bg-primary);font-family:var(--font-sans);font-size:13px;font-weight:600;color:var(--text-secondary);cursor:pointer;transition:var(--transition)}.btn-nav .material-icons{font-size:16px}.btn-nav:hover{background-color:var(--bg-secondary);border-color:var(--text-light)}.btn-nav:disabled{opacity:.5;cursor:not-allowed}.side-panels{background-color:var(--bg-secondary);border-left:1px solid var(--border-color);display:flex;flex-direction:column;height:100vh}.tab-headers{display:grid;grid-template-columns:1fr 1fr;border-bottom:1px solid var(--border-color);flex-shrink:0}.tab-btn{padding:16px;background:none;border:none;font-family:var(--font-sans);font-size:13px;font-weight:700;color:var(--text-light);cursor:pointer;transition:var(--transition);position:relative}.tab-btn.active{color:var(--primary)}.tab-btn.active:after{content:"";position:absolute;bottom:0;left:0;right:0;height:2px;background-color:var(--primary)}.tab-content{display:none;flex:1;overflow-y:auto;padding:24px}.tab-content.active{display:flex;flex-direction:column}.toc-container{display:flex;flex-direction:column;gap:8px}.toc-item{font-size:13px;color:var(--text-secondary);text-decoration:none;cursor:pointer;line-height:1.4;padding:4px 0;transition:var(--transition)}.toc-item:hover{color:var(--primary);transform:translate(2px)}.toc-item.h2{padding-left:0;font-weight:600}.toc-item.h3{padding-left:12px;font-size:12px;color:var(--text-light)}.notes-container{display:flex;flex-direction:column;height:100%}.notes-container textarea{flex:1;width:100%;padding:14px;border-radius:8px;border:1px solid var(--border-color);resize:none;font-family:var(--font-sans);font-size:13px;line-height:1.5;color:var(--text-primary);outline:none;background-color:var(--bg-primary);transition:var(--transition)}.notes-container textarea:focus{border-color:var(--primary)}.notes-status{font-size:11px;color:var(--text-light);margin-top:8px;text-align:right;opacity:0;transition:opacity .3s}.notes-status.show{opacity:1}.empty-state{text-align:center;color:var(--text-light);font-size:13px;margin-top:40px}.mobile-toggle{display:none}@media (max-width: 1024px){.app-container{grid-template-columns:1fr}.sidebar{position:fixed;left:-100%;top:0;width:min(var(--sidebar-width),85vw);z-index:100;transition:left .3s ease;box-shadow:4px 0 10px #0000001a}.sidebar.show{left:0}.side-panels{display:none}.mobile-toggle{display:flex;align-items:center;justify-content:center;position:fixed;bottom:24px;right:24px;width:50px;height:50px;border-radius:50%;background-color:var(--primary);color:#fff;border:none;cursor:pointer;box-shadow:0 4px 10px #2563eb4d;z-index:99}.mobile-toggle .material-icons{font-size:24px}.reader-body{padding:24px 20px}.content-header,.content-footer{padding:0 20px}}@media (max-width: 640px){.content-header{height:auto;padding:16px 20px;flex-direction:column;align-items:flex-start;gap:12px}.breadcrumbs{font-size:12px}.btn-complete{width:100%;justify-content:center;padding:10px 14px}.content-footer{height:auto;padding:16px 20px;gap:12px}.btn-nav{flex:1;justify-content:center;padding:12px 18px}}.katex-display{margin:1.5em auto!important;padding:14px 28px;background-color:var(--bg-secondary);border:1px solid var(--border-color);border-radius:8px;display:block;width:fit-content;max-width:100%;box-shadow:var(--shadow-sm);overflow-x:auto;overflow-y:hidden;text-align:center}.katex{font-size:1.05em}details.interactive-example{margin:24px 0;padding:16px;background-color:var(--bg-secondary);border:1px solid var(--border-color);border-left:4px solid var(--primary);border-radius:8px;box-shadow:var(--shadow-sm);transition:var(--transition)}details.interactive-example[open]{background-color:var(--bg-primary);box-shadow:var(--shadow-md)}details.interactive-example summary{font-weight:700;font-size:14px;color:var(--primary);cursor:pointer;outline:none;-webkit-user-select:none;user-select:none;padding:4px 0}details.interactive-example summary:hover{color:var(--primary-hover)}details.interactive-example .example-content{margin-top:16px;padding-top:16px;border-top:1px solid var(--border-color);font-size:14px;line-height:1.6}.mermaid{display:flex!important;justify-content:center!important;align-items:center!important;margin:28px auto!important;width:100%!important}.reader-body table{margin:24px auto!important;max-width:100%}.reader-body th{text-align:center!important}.reader-body img{display:block;margin:28px auto;max-width:100%;border-radius:8px;box-shadow:var(--shadow-sm)}.katex-display{text-align:center!important}