:root{--bg: #0a0e0a;--bg-elev: #11161a;--bg-elev-2: #182026;--fg: #d3e3d3;--fg-dim: #6e8068;--accent: #4ade80;--accent-bright: #5dde90;--accent-dim: #14532d;--warn: #fbbf24;--error: #f87171;--border: #1e2a1e;font-family:SF Mono,JetBrains Mono,Fira Code,ui-monospace,monospace}*{box-sizing:border-box;margin:0;padding:0}html,body,#root{height:100%}body{background:var(--bg);color:var(--fg);font-size:14px;line-height:1.5}.app{display:grid;grid-template-columns:240px 1fr 1fr;grid-template-rows:48px 1fr auto;grid-template-areas:"topbar  topbar    topbar" "sidebar content   terminal" "sidebar flag      terminal";height:100vh}.topbar{grid-area:topbar;display:flex;align-items:center;justify-content:space-between;padding:0 16px;background:var(--bg-elev);border-bottom:1px solid var(--border)}.topbar h1{font-size:14px;font-weight:600;color:var(--accent)}.topbar h1:before{content:"> ";color:var(--fg-dim)}.topbar .progress{font-size:12px;color:var(--fg-dim)}.sidebar{grid-area:sidebar;background:var(--bg-elev);border-right:1px solid var(--border);overflow-y:auto;padding:12px 0}.sidebar h2{font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--fg-dim);padding:4px 16px 12px;font-weight:500}.sidebar ul{list-style:none}.sidebar li button{background:none;border:none;border-left:2px solid transparent;color:var(--fg);width:100%;text-align:left;padding:8px 16px;font-family:inherit;font-size:13px;cursor:pointer;display:flex;gap:10px;align-items:center}.sidebar li button:hover{background:var(--bg-elev-2)}.sidebar li.active button{background:var(--bg-elev-2);border-left-color:var(--accent)}.sidebar li.done button{color:var(--fg-dim)}.sidebar li .num{color:var(--fg-dim);font-size:11px;min-width:22px}.sidebar li .check{margin-left:auto;color:var(--accent);font-size:12px}.content{grid-area:content;overflow-y:auto;padding:24px 32px;border-right:1px solid var(--border)}.lesson h1,.lesson h2,.lesson h3{color:var(--accent);margin:18px 0 8px;font-weight:600}.lesson h1{font-size:22px;margin-top:0}.lesson h2{font-size:17px}.lesson h3{font-size:14px}.lesson p,.lesson ul,.lesson ol{margin:8px 0 12px}.lesson ul,.lesson ol{padding-left:24px}.lesson code{background:var(--bg-elev);color:var(--accent);padding:1px 6px;border-radius:3px;font-size:13px}.lesson pre{background:var(--bg-elev);border:1px solid var(--border);border-radius:4px;padding:12px 16px;overflow-x:auto;margin:12px 0}.lesson pre code{background:none;padding:0;color:var(--fg)}.lesson table{border-collapse:collapse;margin:12px 0;width:100%;font-size:13px}.lesson th,.lesson td{text-align:left;padding:6px 10px;border:1px solid var(--border)}.lesson th{background:var(--bg-elev);color:var(--accent);font-weight:600}.lesson a{color:var(--accent)}.lesson-actions{margin-top:24px;padding-top:16px;border-top:1px solid var(--border)}button.primary{background:var(--accent);color:var(--bg);border:none;padding:8px 16px;font-family:inherit;font-weight:600;border-radius:3px;cursor:pointer}button.primary:hover{background:var(--accent-bright)}button.primary:disabled{background:var(--accent-dim);color:var(--fg-dim);cursor:default}.terminal-pane{grid-area:terminal;display:flex;flex-direction:column;background:#000}.terminal-pane>header{padding:8px 16px;background:var(--bg-elev);border-bottom:1px solid var(--border);font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--fg-dim)}.terminal-pane iframe{flex:1;border:none;background:#000}.flag-pane{grid-area:flag;padding:12px 32px 16px;background:var(--bg-elev);border-top:1px solid var(--border);border-right:1px solid var(--border)}.flag-pane>header{font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--fg-dim);margin-bottom:8px}.flag-pane form{display:flex;gap:8px}.flag-pane input{flex:1;background:var(--bg);border:1px solid var(--border);color:var(--fg);padding:6px 10px;font-family:inherit;font-size:13px;border-radius:3px}.flag-pane input:focus{outline:none;border-color:var(--accent)}.flag-pane button{background:var(--bg);color:var(--accent);border:1px solid var(--accent);padding:6px 14px;font-family:inherit;font-size:13px;cursor:pointer;border-radius:3px}.flag-pane button:hover{background:var(--accent);color:var(--bg)}.flag-msg{margin-top:8px;font-size:12px;color:var(--accent)}@media (max-width: 900px){.app{grid-template-columns:200px 1fr;grid-template-rows:48px 1fr 200px auto;grid-template-areas:"topbar    topbar" "sidebar   content" "sidebar   terminal" "sidebar   flag"}.terminal-pane{border-top:1px solid var(--border)}}