:root{--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light;color:#111827;background:#f3f4f6;font-family:Helvetica Neue,Arial,sans-serif}*{box-sizing:border-box}body{min-height:100vh;margin:0;line-height:1.5}.app-shell{grid-template-columns:minmax(320px,24vw) 1fr;min-height:100vh;display:grid}.main-content{flex-direction:column;gap:20px;padding:28px;display:flex}.main-header{justify-content:space-between;align-items:center;gap:16px;display:flex}.main-header>div{min-width:0}.main-header h1{margin:0;font-size:2rem;line-height:1.15}.content-grid,.examples-panel{grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;display:grid}.sidebar{color:#f9fafb;background:#111827;flex-direction:column;gap:20px;height:100dvh;padding:24px;display:flex;position:sticky;top:0;overflow:hidden}.brand{letter-spacing:.04em;margin-bottom:16px;font-size:1.4rem;font-weight:700}.progress-summary{background:#1f2937;border-radius:14px;padding:14px}.mobile-lesson-picker{display:none}.lesson-list{overscroll-behavior:contain;scrollbar-gutter:stable;flex-direction:column;flex:1;gap:8px;min-height:0;padding-right:4px;display:flex;overflow-y:auto}.lesson-list::-webkit-scrollbar{width:8px}.lesson-list::-webkit-scrollbar-track{background:0 0}.lesson-list::-webkit-scrollbar-thumb{background:#374151;border-radius:999px}.lesson-list:hover::-webkit-scrollbar-thumb{background:#4b5563}.lesson-item{cursor:pointer;background:#1f2937;border-radius:12px;padding:12px;transition:transform .15s,background 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#1f2937;border-radius:14px;outline:none;width:100%;min-height:260px;padding:16px;font-family:SFMono-Regular,Menlo,Monaco,Consolas,Liberation Mono,Courier New,monospace;font-size:.96rem;line-height:1.55;overflow:auto}.code-editor::selection{background:#38bdf852}.code-editor ::selection{background:#38bdf852}.code-editor:focus{box-shadow:inset 0 0 0 2px #38bdf8}.code-sample code{font:inherit}pre{white-space:pre-wrap;word-break:break-word;background:#f3f4f6;border-radius:14px;margin:0;padding:16px;font-size:.95rem}.code-sample{color:#f8fafc;background:#111827;margin-bottom:10px;padding:16px;overflow-x:auto}.code-sample.success{background:#064e3b}.token-comment{color:#94a3b8;font-style:italic}.token-string,.token-regexp{color:#86efac}.token-keyword{color:#93c5fd}.token-builtin{color:#67e8f9}.token-function{color:#fbbf24}.token-number,.token-constant{color:#fca5a5}.primary-btn,.secondary-btn{cursor:pointer;font:inherit;border:none;border-radius:12px;padding:12px 18px;font-weight:600}.primary-btn{color:#fff;background:#4338ca}.primary-btn.completed{color:#334155;background:#e2e8f0}.primary-btn:disabled{cursor:not-allowed;opacity:.68}.primary-btn.completed:disabled{opacity:1}.secondary-btn{color:#111827;background:#e5e7eb}@media (width<=980px){.app-shell{grid-template-columns:1fr;min-height:auto}.sidebar{gap:12px;height:auto;padding:18px 16px 14px;position:static;overflow:hidden}.brand{margin-bottom:0;font-size:1.15rem}.progress-summary{border-radius:12px;justify-content:space-between;align-items:center;gap:12px;padding:10px 12px;font-size:.9rem;display:flex}.mobile-lesson-picker{color:#cbd5e1;flex-direction:column;gap:6px;font-size:.82rem;font-weight:700;display:flex}.mobile-lesson-picker select{color:#f9fafb;width:100%;min-height:44px;font:inherit;background:#1f2937;border:1px solid #4b5563;border-radius:12px;padding:0 38px 0 12px;font-size:.95rem}.lesson-list{display:none}.main-content{gap:14px;padding:18px 16px 24px}.main-header{flex-direction:column;align-items:stretch;gap:12px}.main-header h1{font-size:1.45rem}.study-tabs{grid-template-columns:repeat(4,minmax(0,1fr));gap:6px;display:grid}.study-tab{min-width:0;padding:8px 6px}.content-grid{grid-template-columns:1fr}.primary-btn,.secondary-btn{min-height:44px}.main-header .primary-btn{width:100%}.panel{border-radius:14px;padding:16px;box-shadow:0 8px 24px #0f172a0f}.panel-header{flex-direction:column;align-items:stretch;gap:10px}.button-row{grid-template-columns:1fr;display:grid}.code-editor{border-radius:12px;min-height:220px;padding:12px;font-size:1rem}pre{border-radius:12px;padding:12px;font-size:.9rem}.examples-panel{grid-template-columns:1fr}}@media (width<=420px){.main-header h1{font-size:1.3rem}}