:root {
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --bg-hover: #eceef2;
  --fg: #1f2328;
  --fg-muted: #656d76;
  --border: #d8dee4;
  --accent: #2f6feb;
  --accent-fg: #ffffff;
  --danger: #cf222e;
  --code-bg: #f3f4f6;
  --radius: 8px;
  --side-w: 280px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --bg-soft: #161a20;
    --bg-hover: #1f242c;
    --fg: #e6e8eb;
    --fg-muted: #9aa4af;
    --border: #2b313a;
    --accent: #4c8dff;
    --danger: #ff6b6b;
    --code-bg: #1b2028;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font: 15px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
button, input, textarea { font: inherit; color: inherit; }

.topbar {
  height: 52px; display: flex; align-items: center; gap: 12px;
  padding: 0 16px; border-bottom: 1px solid var(--border); background: var(--bg);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-weight: 700; color: var(--fg); text-decoration: none; font-size: 17px; }
.spacer { flex: 1; }
.crumbs { display: flex; gap: 4px; min-width: 0; overflow: hidden; white-space: nowrap; color: var(--fg-muted); }
.crumbs a { color: var(--fg-muted); text-decoration: none; }
.crumbs a:hover { color: var(--accent); }

.btn, .link-btn, .icon-btn {
  border: 1px solid var(--border); background: var(--bg); border-radius: var(--radius);
  padding: 5px 12px; cursor: pointer; text-decoration: none; color: var(--fg); font-size: 14px; white-space: nowrap;
}
.btn:hover, .link-btn:hover, .icon-btn:hover { background: var(--bg-hover); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.btn.danger { color: var(--danger); }
.btn:disabled { opacity: .5; cursor: default; }
.icon-btn { padding: 4px 10px; }

.layout { display: flex; height: calc(100% - 52px); }
.sidebar {
  width: var(--side-w); flex-shrink: 0; border-right: 1px solid var(--border);
  background: var(--bg-soft); display: flex; flex-direction: column; overflow: hidden;
}
.side-actions { display: flex; gap: 6px; padding: 12px 12px 0; flex-wrap: wrap; }
.side-actions .btn { flex: 1; padding: 5px 6px; }
.filter {
  margin: 12px; padding: 6px 10px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg);
}
.tree { flex: 1; overflow: auto; padding: 0 6px 16px; }
.node {
  display: flex; align-items: center; gap: 6px; padding: 3px 8px; border-radius: 6px;
  cursor: pointer; user-select: none; color: var(--fg); text-decoration: none; white-space: nowrap;
}
.node:hover { background: var(--bg-hover); }
.node.active { background: var(--accent); color: var(--accent-fg); }
.node .ico { width: 18px; text-align: center; flex-shrink: 0; }
.node .name { overflow: hidden; text-overflow: ellipsis; }
.node.drop-target { outline: 2px dashed var(--accent); }
.children { padding-left: 14px; }
.children.collapsed { display: none; }
.empty-tip { color: var(--fg-muted); padding: 8px 12px; font-size: 13px; }

.main { flex: 1; overflow: auto; min-width: 0; }
.toolbar {
  display: flex; gap: 8px; padding: 10px 24px; border-bottom: 1px solid var(--border);
  position: sticky; top: 0; background: var(--bg); z-index: 5; flex-wrap: wrap; align-items: center;
}
.toolbar:empty { display: none; }
.toolbar .title { font-weight: 600; margin-right: auto; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.view { padding: 24px; }

/* Markdown 正文 */
.md { max-width: 900px; margin: 0 auto; word-wrap: break-word; }
.md h1, .md h2 { border-bottom: 1px solid var(--border); padding-bottom: .3em; }
.md a { color: var(--accent); }
.md img, .md video { max-width: 100%; border-radius: 6px; }
.md code { background: var(--code-bg); padding: .15em .4em; border-radius: 4px; font-size: 90%; }
.md pre { background: var(--code-bg); padding: 14px; border-radius: var(--radius); overflow: auto; }
.md pre code { background: none; padding: 0; }
.md blockquote { margin: 0; padding: 0 1em; color: var(--fg-muted); border-left: 4px solid var(--border); }
.md table { border-collapse: collapse; display: block; overflow: auto; }
.md th, .md td { border: 1px solid var(--border); padding: 6px 12px; }
.md tr:nth-child(2n) { background: var(--bg-soft); }
.md hr { border: 0; border-top: 1px solid var(--border); }

/* 编辑器 */
.editor { display: grid; grid-template-columns: 1fr 1fr; gap: 0; height: calc(100vh - 52px - 55px); }
.editor textarea {
  border: 0; border-right: 1px solid var(--border); resize: none; padding: 20px; outline: none;
  background: var(--bg-soft); font: 14px/1.6 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; tab-size: 2;
}
.editor .preview { overflow: auto; padding: 20px; }
.view.editing { padding: 0; }

/* 文件夹视图 */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 12px; }
.card {
  border: 1px solid var(--border); border-radius: var(--radius); padding: 12px; cursor: pointer;
  text-decoration: none; color: var(--fg); display: flex; flex-direction: column; gap: 6px; min-width: 0; background: var(--bg);
}
.card:hover { border-color: var(--accent); }
.card .thumb {
  height: 100px; display: flex; align-items: center; justify-content: center; font-size: 40px;
  background: var(--bg-soft); border-radius: 6px; overflow: hidden;
}
.card .thumb img, .card .thumb video { width: 100%; height: 100%; object-fit: cover; }
.card .cname { font-size: 13px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.card .meta { font-size: 12px; color: var(--fg-muted); }

.media-view { text-align: center; }
.media-view img, .media-view video { max-width: 100%; max-height: calc(100vh - 180px); border-radius: var(--radius); }
.media-view iframe { width: 100%; height: calc(100vh - 160px); border: 1px solid var(--border); border-radius: var(--radius); }
.muted { color: var(--fg-muted); }

.drop-mask {
  display: none; position: fixed; inset: 0; background: color-mix(in srgb, var(--accent) 18%, transparent);
  border: 3px dashed var(--accent); z-index: 50; align-items: center; justify-content: center;
  font-size: 22px; font-weight: 600; color: var(--accent); pointer-events: none;
}
.drop-mask.show { display: flex; }

.toast {
  position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); background: var(--fg); color: var(--bg);
  padding: 8px 16px; border-radius: var(--radius); opacity: 0; transition: opacity .2s; pointer-events: none; z-index: 60;
  max-width: calc(100vw - 32px);
}
.toast.show { opacity: .92; }

dialog {
  border: 1px solid var(--border); border-radius: 12px; background: var(--bg); color: var(--fg);
  padding: 20px; width: min(420px, calc(100vw - 32px));
}
dialog::backdrop { background: rgba(0, 0, 0, .4); }
dialog h3 { margin: 0 0 8px; }
dialog p { margin: 0 0 12px; color: var(--fg-muted); white-space: pre-wrap; }
dialog input { width: 100%; padding: 8px 10px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg); }
.dlg-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 16px; }

.lock { max-width: 340px; margin: 12vh auto 0; text-align: center; display: flex; flex-direction: column; gap: 10px; }
.lock-ico { font-size: 40px; }
.lock h2 { margin: 0; }
.lock p { margin: 0; }
.lock input { padding: 9px 12px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg); text-align: center; }
.lock-err { color: var(--danger); min-height: 1.4em; font-size: 14px; }
body.locked .sidebar, body.locked #authBtn, body.locked .crumbs { display: none; }

body:not(.can-write) .write-only { display: none !important; }
.only-mobile { display: none; }

@media (max-width: 760px) {
  .only-mobile { display: inline-block; }
  .sidebar {
    position: fixed; top: 52px; bottom: 0; left: 0; z-index: 20; transform: translateX(-100%);
    transition: transform .2s; width: min(85vw, 320px);
  }
  .sidebar.open { transform: none; box-shadow: 0 0 24px rgba(0,0,0,.3); }
  .view { padding: 16px; }
  .toolbar { padding: 8px 16px; }
  .editor { grid-template-columns: 1fr; grid-template-rows: 1fr 1fr; }
  .editor textarea { border-right: 0; border-bottom: 1px solid var(--border); }
  .crumbs { display: none; }
}