:root {
    color-scheme: light dark;
    --bg: #fbfaf8;
    --panel: #ffffff;
    --ink: #1a1a19;
    --muted: #77736c;
    --line: #e6e2db;
    --accent: #b4541e;
    --accent-soft: #fdf1e9;
    --code: #f4f1ec;
    --radius: 10px;
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --bg: #16161a;
      --panel: #1d1d22;
      --ink: #e8e6e1;
      --muted: #97928a;
      --line: #2e2e35;
      --accent: #e8834a;
      --accent-soft: #2a1f18;
      --code: #26262c;
    }
  }
  * { box-sizing: border-box; }
  html, body { height: 100%; }
  body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font: 15px/1.6 ui-sans-serif, -apple-system, "Segoe UI", Inter, system-ui, sans-serif;
    display: flex;
    flex-direction: column;
  }
  button, input, textarea { font: inherit; color: inherit; }

  header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 16px;
    border-bottom: 1px solid var(--line);
    background: var(--panel);
    flex-wrap: wrap;
  }
  .brand {
    font-weight: 650;
    letter-spacing: -0.01em;
    margin-right: auto;
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .brand small { color: var(--muted); font-weight: 400; letter-spacing: 0; }
  @media (max-width: 720px) { .brand small { display: none; } }

  button {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 7px 13px;
    cursor: pointer;
    transition: background .15s, border-color .15s;
  }
  button:hover { border-color: var(--muted); }
  button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
  button.primary:hover { filter: brightness(1.08); }
  button.on { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }

  main { flex: 1; display: grid; grid-template-columns: 1fr 1fr; min-height: 0; }
  @media (max-width: 860px) {
    main { grid-template-columns: 1fr; }
    main[data-view="write"] .side-preview { display: none; }
    main[data-view="read"] .side-editor { display: none; }
  }
  @media (min-width: 861px) { #toggleView { display: none; } }

  .side-editor { border-right: 1px solid var(--line); display: flex; min-height: 0; }
  textarea {
    flex: 1;
    border: 0;
    outline: 0;
    resize: none;
    padding: 24px clamp(16px, 4vw, 40px);
    background: transparent;
    font-family: ui-monospace, "SF Mono", "Cascadia Code", Menlo, monospace;
    font-size: 14px;
    line-height: 1.7;
    tab-size: 2;
  }
  .side-preview { overflow: auto; padding: 24px clamp(16px, 4vw, 40px); }

  .note h1, .note h2, .note h3 { line-height: 1.25; letter-spacing: -0.02em; margin: 1.4em 0 .5em; }
  .note h1 { font-size: 1.9em; margin-top: .2em; }
  .note h2 { font-size: 1.4em; }
  .note h3 { font-size: 1.15em; }
  .note p { margin: .8em 0; }
  .note ul, .note ol { padding-left: 1.3em; margin: .7em 0; }
  .note li { margin: .25em 0; }
  .note code { background: var(--code); padding: .15em .4em; border-radius: 5px; font-size: .9em; }
  .note pre { background: var(--code); padding: 14px 16px; border-radius: var(--radius); overflow-x: auto; }
  .note pre code { background: none; padding: 0; }
  .note blockquote { margin: .8em 0; padding-left: 14px; border-left: 3px solid var(--line); color: var(--muted); }
  .note hr { border: 0; border-top: 1px solid var(--line); margin: 1.6em 0; }
  .note a { color: var(--accent); }
  .note img { max-width: 100%; }
  .task input { margin-right: .5em; }
  .task.done { color: var(--muted); text-decoration: line-through; }

  footer {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 8px 16px;
    border-top: 1px solid var(--line);
    background: var(--panel);
    color: var(--muted);
    font-size: 12.5px;
    flex-wrap: wrap;
  }
  footer .grow { margin-left: auto; }
  .warn { color: var(--accent); }

  dialog {
    border: 1px solid var(--line);
    border-radius: 14px;
    background: var(--panel);
    color: var(--ink);
    padding: 24px;
    max-width: 380px;
    width: calc(100% - 32px);
    box-shadow: 0 18px 50px rgba(0,0,0,.18);
  }
  dialog::backdrop { background: rgba(0,0,0,.45); }
  dialog h2 { margin: 0 0 6px; font-size: 1.1em; }
  dialog p { margin: 0 0 14px; color: var(--muted); font-size: 13px; }
  dialog input {
    width: 100%;
    padding: 9px 11px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--bg);
    margin-bottom: 12px;
  }
  .row { display: flex; gap: 8px; justify-content: flex-end; }
  .err { color: #d1453b; font-size: 13px; margin-bottom: 10px; }