.python-page{font-family:var(--font);background:var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;font-size:15px;line-height:1.75}.python-page .lesson{display:none}.python-page .lesson.show{display:block}:root{--bg:#faf9f6;--surface:#fff;--surface-alt:#f5f3ee;--text:#1a1a2e;--text-muted:#6b7280;--text-light:#9ca3af;--accent:#4f46e5;--accent-light:#eef2ff;--accent-dark:#3730a3;--amber:#d97706;--amber-light:#fef3c7;--success:#059669;--success-light:#d1fae5;--error:#dc2626;--error-light:#fee2e2;--border:#e5e7eb;--border-strong:#d1d5db;--code-bg:#1e1e3f;--code-text:#d4d4ff;--radius:14px;--radius-sm:8px;--shadow-sm:0 1px 2px #0000000d;--shadow:0 2px 8px #0000000f;--shadow-lg:0 8px 30px #00000014;--sidebar-w:290px;--font:-apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", "Segoe UI", sans-serif;--mono:"JetBrains Mono", "SF Mono", "Fira Code", Consolas, 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.subtitle{color:var(--text-muted);margin-top:4px;margin-left:40px;font-size:12px}.progress-wrap{margin-top:14px;margin-left:40px}.progress-bar{background:var(--surface-alt);border-radius:3px;height:6px;overflow:hidden}.progress-fill{background:linear-gradient(90deg,var(--accent),var(--amber));border-radius:3px;width:0;height:100%;transition:width .4s}.progress-text{color:var(--text-muted);margin-top:4px;font-size:11px}.sidebar-nav{scrollbar-width:none;flex:1;padding:12px 0;overflow-y:auto}.sidebar-nav::-webkit-scrollbar{display:none}.sidebar-nav:after{content:"";background:linear-gradient(to bottom,transparent,var(--surface));pointer-events:none;height:28px;margin:0 0 -12px;display:block;position:sticky;bottom:0;left:0;right:0}.week-group{margin-bottom:6px}.week-label{color:var(--text-light);text-transform:uppercase;letter-spacing:.5px;padding:10px 20px 4px;font-size:11px;font-weight:700}.day-item{cursor:pointer;color:var(--text);border-left:3px solid 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