:root {
  color-scheme: light dark;
  --fs: 15px;
  --bg: #ffffff; --bg2: #f6f8fa; --fg: #1f2328; --muted: #59636e;
  --line: #d1d9e0; --accent: #0969da; --accent-fg: #ffffff;
  --danger: #cf222e; --code-bg: #f6f8fa;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1e1e1e; --bg2: #252526; --fg: #e6edf3; --muted: #8d96a0;
    --line: #3c3c3c; --accent: #0e639c; --accent-fg: #ffffff;
    --danger: #f85149; --code-bg: #161b22;
  }
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0; display: flex; flex-direction: column; background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: var(--fs);
  line-height: 1.5;
  -webkit-text-size-adjust: 100%;
}
.hidden { display: none !important; }
button {
  font: inherit; color: inherit; background: var(--bg2);
  border: 1px solid var(--line); border-radius: 6px; padding: .3rem .7rem;
}
button:disabled { opacity: .45; }
button.active { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }

/* header */
header {
  display: flex; align-items: center; gap: .45rem; padding: .45rem .6rem;
  border-bottom: 1px solid var(--line); background: var(--bg2);
  padding-top: max(.45rem, env(safe-area-inset-top));
}
header .spacer { flex: 1; }
#filename { font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
#dirty { color: var(--accent); }
#save { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }

/* layout */
#body { flex: 1; display: flex; min-height: 0; }
#tree-pane {
  width: 270px; border-right: 1px solid var(--line); background: var(--bg2);
  display: flex; flex-direction: column; min-height: 0;
}
@media (min-width: 701px) {
  #tree-pane.collapsed { display: none; }
}
#tree { flex: 1; overflow: auto; padding: .4rem; }
.tree-actions, .tree-foot { display: flex; flex-wrap: wrap; gap: .35rem; padding: .45rem; }
.tree-foot { border-top: 1px solid var(--line); }
.font-row {
  display: flex; align-items: center; gap: .5rem; padding: .35rem .6rem;
  border-top: 1px solid var(--line); color: var(--muted);
}
.font-row input { flex: 1; min-width: 0; }
.fa-small { font-size: 12px; }
.fa-large { font-size: 19px; }
.tree-foot button, .tree-actions button { font-size: .85rem; }
#logout { margin-left: auto; }
#delete { color: var(--danger); }

/* tree */
.node { user-select: none; -webkit-user-select: none; }
.node > .row {
  display: flex; align-items: center; gap: .35rem; padding: .3rem .35rem;
  border-radius: 5px; cursor: pointer; word-break: break-all;
}
.node > .row:hover { background: color-mix(in srgb, var(--accent) 12%, transparent); }
.node > .row.selected { background: var(--accent); color: var(--accent-fg); }
.node .children { padding-left: .95rem; }
.node > .row.ghost { opacity: .4; cursor: default; }
.node > .row.ghost:hover { background: none; }
.caret { width: 1em; text-align: center; font-size: .8em; color: var(--muted); }
.row.selected .caret { color: inherit; }

/* panes */
#panes { flex: 1; display: flex; min-width: 0; }
#editor, #preview { flex: 1; min-width: 0; overflow: auto; }
#editor {
  border: 0; outline: none; resize: none; background: var(--bg); color: var(--fg);
  padding: 1rem; font-family: ui-monospace, Menlo, Consolas, monospace;
  font-size: calc(var(--fs) - 1px); line-height: 1.6;
}
#preview { padding: 1rem 1.2rem 4rem; }
#panes.split #editor { border-right: 1px solid var(--line); }
#preview .placeholder { color: var(--muted); }
#preview img { max-width: 100%; }
#preview pre { background: var(--code-bg); padding: .8rem; border-radius: 8px; overflow-x: auto; }
#preview code { background: var(--code-bg); padding: .1em .35em; border-radius: 5px;
  font-size: .9em; font-family: ui-monospace, Menlo, monospace; }
#preview pre code { padding: 0; background: none; }
#preview table { border-collapse: collapse; display: block; overflow-x: auto; }
#preview th, #preview td { border: 1px solid var(--line); padding: .35rem .6rem; }
#preview blockquote { margin: 0 0 1rem; padding-left: 1rem;
  border-left: 4px solid var(--line); color: var(--muted); }
#preview h1, #preview h2 { border-bottom: 1px solid var(--line); padding-bottom: .25rem; }
#preview a { color: var(--accent); }
#preview input[type=checkbox] { transform: scale(1.15); margin-right: .4rem; }
#preview li.task { list-style: none; }
#preview li.task::marker { content: ""; }

/* pdf viewer */
#preview.pdf { padding: .8rem .8rem 4rem; background: var(--bg2); }
.pdf-page {
  margin: 0 auto .8rem; max-width: 60rem; background: #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, .35);
}
.pdf-page canvas { display: block; width: 100%; height: auto; }

/* login overlay */
.overlay {
  position: fixed; inset: 0; background: var(--bg); z-index: 10;
  display: flex; align-items: center; justify-content: center;
}
.overlay form { display: flex; flex-direction: column; gap: .8rem; width: min(20rem, 85vw); }
.overlay input {
  font: inherit; padding: .55rem .7rem; border: 1px solid var(--line);
  border-radius: 6px; background: var(--bg2); color: var(--fg);
}
.overlay button { background: var(--accent); color: var(--accent-fg);
  border-color: var(--accent); padding: .55rem; }
#login-error { color: var(--danger); min-height: 1.2em; margin: 0; }

/* toast */
#toast {
  position: fixed; bottom: 1.2rem; left: 50%; transform: translateX(-50%);
  background: var(--fg); color: var(--bg); padding: .5rem .9rem;
  border-radius: 8px; z-index: 20; max-width: 90vw;
}

/* mobile: tree becomes a drawer, split hidden */
@media (max-width: 700px) {
  .wide-only { display: none; }
  #tree-pane {
    position: fixed; top: 0; bottom: 0; left: 0; z-index: 5;
    transform: translateX(-100%); transition: transform .18s ease;
    width: min(20rem, 85vw); box-shadow: 4px 0 18px rgba(0,0,0,.25);
    padding-top: env(safe-area-inset-top);
  }
  #tree-pane.open { transform: none; }
}