:root{--bg-page: #f6f8fa;--bg-card: #ffffff;--bg-hover: #f3f4f6;--border-color: #d0d7de;--border-light: #e5e7eb;--primary: #4da3ff;--primary-hover: #3a96fa;--secondary: #0984e3;--text-main: #24292f;--text-muted: #57606a;--success: #1a7f37;--success-bg: #dafbe1;--warning: #9a6700;--warning-bg: #fff8c5;--radius-sm: 4px;--radius-md: 6px}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html,body{width:100%;max-width:100%;overflow-x:hidden;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Helvetica,Arial,sans-serif;background-color:var(--bg-page);color:var(--text-main);font-size:14px;line-height:1.5}#learn-root{width:100%;min-height:100vh;display:flex;flex-direction:column}a{color:inherit;text-decoration:none}.card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-sm);padding:24px;width:100%}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:8px 16px;font-size:14px;font-weight:600;border-radius:var(--radius-sm);cursor:pointer;transition:background .15s ease;border:1px solid var(--border-color);background:var(--bg-card);color:var(--text-main);text-align:center}.btn:hover{background:var(--bg-hover)}.btn-primary{background:var(--primary);color:#fff;border-color:#1b1f2426}.btn-primary:hover{background:var(--primary-hover)}.status-badge{padding:4px 8px;border-radius:var(--radius-sm);font-size:12px;font-weight:600;border:1px solid var(--border-color);background:#f6f8fa;color:var(--text-main);display:inline-flex;align-items:center;gap:4px;white-space:nowrap}.timeline-hub{position:relative;padding-left:28px;margin-top:24px}.timeline-hub:before{content:"";position:absolute;top:10px;bottom:10px;left:11px;width:2px;background:var(--border-color)}.timeline-item{position:relative;margin-bottom:20px}.timeline-point{position:absolute;left:-28px;top:16px;width:24px;height:24px;border-radius:4px;background:#fff;border:2px solid var(--border-color);display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:700;color:var(--text-muted);z-index:2}.timeline-point.completed{background:var(--success-bg);border-color:var(--success);color:var(--success)}.timeline-point.active{background:var(--primary);border-color:var(--secondary);color:#fff}.markdown-body h1{font-size:22px;font-weight:700;margin:0 0 16px;color:var(--text-main)}.markdown-body h2{font-size:17px;font-weight:600;margin:24px 0 12px;color:var(--text-main);border-bottom:1px solid var(--border-light);padding-bottom:6px}.markdown-body h3{font-size:15px;font-weight:600;margin:16px 0 8px;color:var(--text-main)}.markdown-body p{margin-bottom:16px;line-height:1.6}.markdown-body ul,.markdown-body ol{margin:0 0 16px 24px}.markdown-body li{margin-bottom:6px}.markdown-body blockquote{border-left:4px solid var(--border-color);color:var(--text-muted);padding-left:16px;margin:16px 0}.markdown-body pre{background:#f6f8fa;border:1px solid var(--border-color);border-radius:var(--radius-sm);padding:16px;overflow-x:auto;margin:16px 0;font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;font-size:13px}.markdown-body code{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;background:#afb8c133;padding:2px 6px;border-radius:3px;font-size:13px}.markdown-body pre code{background:transparent;padding:0}@media (max-width: 768px){.btn{width:100%;padding:10px}.card{padding:16px}.status-badge{font-size:11px;padding:3px 6px}}