*{box-sizing:border-box}
body{margin:0;font-family:Segoe UI,Apple SD Gothic Neo,sans-serif;background:#0b1020;color:#eaf0ff}
header{padding:14px 18px;border-bottom:1px solid #253055;position:sticky;top:0;background:#0b1020;z-index:20}
h1{margin:0;font-size:20px}.muted{opacity:.75;font-size:12px}
main{display:grid;grid-template-columns:320px 1fr;min-height:calc(100vh - 64px)}
aside{border-right:1px solid #253055;padding:12px;overflow:auto;max-height:calc(100vh - 64px)}
section{padding:16px;overflow:auto;max-height:calc(100vh - 64px)}
.toolbar{display:flex;justify-content:space-between;gap:8px;align-items:center;flex-wrap:wrap}
.toolbar h2{margin:0;font-size:18px}
button{background:#1a2550;color:#eaf0ff;border:1px solid #2a3d70;border-radius:10px;padding:8px 12px;cursor:pointer}
button:disabled{opacity:.45;cursor:not-allowed}
input{width:100%;padding:12px;border-radius:10px;border:1px solid #2b3b6c;background:#131a33;color:#fff;font-size:16px}

.chips{display:flex;gap:8px;flex-wrap:wrap;margin:10px 0 8px}
.chip{padding:6px 10px;border-radius:999px;background:#131f44;border:1px solid #334b85;font-size:13px}
.chip.active{background:#20408f;border-color:#5e86e3}

.tree-list{list-style:none;padding:0;margin:8px 0}
.tree-list li{margin:4px 0}
details{background:#101833;border:1px solid #23386e;border-radius:10px;padding:6px 8px}
summary{cursor:pointer;font-weight:600;padding:4px 2px}
details > ul{margin:6px 0 0 8px;padding-left:8px;border-left:1px dashed #29467f}
.file-btn{width:100%;text-align:left;background:#111935;padding:10px 12px;min-height:42px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.file-btn.active{border-color:#7da3ff;background:#1a2a57}

.markdown{line-height:1.75;white-space:normal;font-size:16px;margin-top:10px}
.editor{width:100%;min-height:60vh;margin-top:10px;padding:12px;border-radius:10px;background:#091126;color:#dbe6ff;border:1px solid #2a3d70;font-family:Consolas,monospace;font-size:14px}
.hidden{display:none}

@media (max-width: 900px){
  main{grid-template-columns:1fr}
  aside{border-right:0;border-bottom:1px solid #253055;max-height:none}
  section{max-height:none}
  header{position:static}
  .toolbar h2{font-size:16px}
  .file-btn{font-size:14px}
}