*{box-sizing:border-box}body{margin:0;background:#f2f6fc;color:#15243b;font:16px/1.65 "Noto Sans Telugu","Nirmala UI",Gautami,system-ui,sans-serif}button,input,select{font:inherit}button,a,select{min-height:42px}.head{background:linear-gradient(120deg,#17356e,#316ac3);color:white;padding:24px max(18px,calc((100vw - 1200px)/2));}.head a{color:#fff}.head h1{margin:8px 0}.toolbar{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.toolbar input{padding:10px;border-radius:9px;border:1px solid #cbd5e1;flex:1;min-width:180px}.toolbar select,.toolbar button{border:1px solid #a9c8ff;border-radius:9px;padding:8px;background:white;color:#163b75}.layout{max-width:1240px;margin:20px auto;padding:0 16px;display:grid;grid-template-columns:290px minmax(0,1fr);gap:16px}.nav,.lesson{background:white;border:1px solid #dbe4f0;border-radius:15px;padding:20px;min-width:0}.nav h2{margin:0 0 12px}.menu-btn{display:block;width:100%;text-align:left;border:1px solid #dbe4f0;border-radius:9px;padding:10px;margin:6px 0;background:#f8faff;color:#1a355e;cursor:pointer}.menu-btn.active,.stepbar button.active{background:#2256a5;color:#fff}.level{display:inline-block;background:#e7f1ff;border-radius:20px;padding:3px 12px;color:#20519c;font-weight:700}.stepbar{display:flex;flex-wrap:wrap;gap:8px}.stepbar button{border:1px solid #cbd8ec;border-radius:8px;padding:8px;background:#f5f8fd;cursor:pointer}.codehead{display:flex;align-items:center;justify-content:space-between;gap:10px}.codehead button,.actions button{border:0;background:#255bb1;color:white;padding:9px 14px;border-radius:9px;cursor:pointer}pre{background:#13243c;color:#f1f5fa;border-radius:12px;padding:18px;overflow:auto;white-space:pre-wrap;overflow-wrap:anywhere;font:14px/1.65 Consolas,monospace;direction:ltr;text-align:left}.actions{display:flex;flex-wrap:wrap;gap:10px}.actions button:disabled{opacity:.45;cursor:not-allowed}#status{color:#17683c}button:focus-visible,a:focus-visible{outline:3px solid #ffb74d;outline-offset:2px}@media(max-width:850px){.layout{grid-template-columns:1fr}.nav{max-height:310px;overflow:auto}.head{padding:20px}.lesson{padding:15px}}