:root {
  --ink: #1f2328;
  --muted: #59636e;
  --line: #d6dbe1;
  --panel: #f6f8fa;
  --accent: #335588;
  --accent-ink: #ffffff;
  --sel: #e05a00;
  --danger: #b42318;
  color-scheme: light;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; height: 100%; }
body {
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink); background: #fff; display: flex; flex-direction: column; overflow: hidden;
}
code { font-family: Consolas, Menlo, monospace; font-size: .92em; }

/* ---- top bar */
#bar {
  display: flex; align-items: center; gap: 16px; padding: 8px 16px;
  border-bottom: 1px solid var(--line); background: #fff; flex-wrap: wrap; z-index: 5;
}
.brand { display: flex; align-items: center; gap: 8px; font-weight: 600; font-size: 15px; white-space: nowrap; }
.info { color: var(--muted); font-size: 13px; flex: 1; min-width: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.info b { color: var(--ink); font-weight: 600; }
.actions { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
#find { height: 32px; border: 1px solid var(--line); border-radius: 6px; padding: 0 10px; font: inherit; font-size: 13px; width: 180px; }
.btn {
  height: 32px; padding: 0 14px; border: 1px solid var(--line); border-radius: 6px; background: #fff;
  font: inherit; font-size: 13px; cursor: pointer; color: var(--ink);
}
.btn:hover:not(:disabled) { background: var(--panel); }
.btn:disabled { opacity: .45; cursor: default; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover:not(:disabled) { background: #2a476f; }
.btn.danger { color: var(--danger); border-color: #f1b5ae; }
.btn.danger:hover:not(:disabled) { background: #fdf0ee; }
.btn.big { height: 42px; padding: 0 22px; font-size: 15px; }

/* ---- welcome */
#main { position: relative; flex: 1; min-height: 0; }
#welcome { position: absolute; inset: 0; display: grid; place-items: center; padding: 16px; overflow: auto; }
.drop {
  max-width: 560px; width: 100%; text-align: center; padding: 40px 28px;
  border: 2px dashed var(--line); border-radius: 14px; transition: border-color .15s, background .15s;
}
.drop.over { border-color: var(--accent); background: #f2f6fb; }
.drop h1 { font-size: 26px; margin: 0 0 10px; }
.drop p { color: var(--muted); line-height: 1.5; margin: 0 0 20px; }
.drop .hint { margin: 12px 0 0; font-size: 13px; }
#demos { margin-top: 26px; display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }
#demos .label { width: 100%; font-size: 12px; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; }
#demos button { border-radius: 999px; }

/* ---- viewer */
#viewer { position: absolute; inset: 0; }
#wrap { position: absolute; inset: 0; overflow: auto; cursor: default; }
#wrap.grab { cursor: grabbing; }
#svg { display: block; margin: 0 auto; }
#tools { position: absolute; left: 12px; bottom: 12px; display: flex; gap: 6px; }
#tools button {
  width: 32px; height: 32px; border: 1px solid var(--line); border-radius: 6px; background: #fff;
  cursor: pointer; font-size: 15px; color: var(--ink);
}
#tools button:hover { background: var(--panel); }

.node { cursor: pointer; }
.node .body { fill: #fff; stroke: #333; stroke-width: 1; }
.node .io { fill: #eee; stroke: #333; stroke-width: 1; }
.node.sel .body, .node.sel .io, .node.sel .hdr { stroke: var(--sel); stroke-width: 2.5; }
.node text { font-size: 11px; dominant-baseline: central; }
.edge path { fill: none; stroke: #000; stroke-width: 1; }
.edge text { font-size: 10px; text-anchor: middle; dominant-baseline: central; }

/* ---- side panel */
#side {
  position: absolute; top: 0; right: 0; bottom: 0; width: 360px; max-width: 100%;
  background: var(--panel); border-left: 1px solid var(--line); overflow: auto; padding: 14px 16px 24px; font-size: 12.5px;
}
#side .close { position: absolute; top: 6px; right: 8px; border: 0; background: none; font-size: 22px; color: var(--muted); cursor: pointer; }
#side h2 { margin: 2px 28px 12px 0; font-size: 16px; }
#side .sec { margin: 16px 0 6px; font-weight: 600; color: var(--muted); text-transform: uppercase; font-size: 11px; letter-spacing: .05em; }
#side .kv { display: flex; gap: 10px; padding: 4px 0; border-bottom: 1px solid #e6e9ed; }
#side .k { width: 110px; flex: none; color: var(--muted); word-break: break-all; }
#side .v { font-family: Consolas, Menlo, monospace; word-break: break-all; }
#side .edit { background: #fff; border: 1px solid var(--line); border-radius: 8px; padding: 10px; margin-top: 6px; }
#side .edit label { display: block; font-size: 12px; color: var(--muted); margin-bottom: 4px; }
#side .row { display: flex; gap: 6px; }
#side input[type=text] { flex: 1; min-width: 0; height: 30px; border: 1px solid var(--line); border-radius: 6px; padding: 0 8px; font: inherit; font-family: Consolas, Menlo, monospace; font-size: 12px; }
#side .edit .btn { height: 30px; }
#side .note { color: var(--muted); font-size: 11.5px; margin: 8px 0 0; line-height: 1.4; }

/* ---- toast + busy */
#toast {
  position: absolute; left: 50%; bottom: 18px; transform: translateX(-50%) translateY(20px); opacity: 0;
  background: #1f2328; color: #fff; padding: 10px 16px; border-radius: 8px; font-size: 13px; max-width: min(640px, 90%);
  transition: opacity .2s, transform .2s; pointer-events: none; z-index: 20; line-height: 1.4;
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
#toast.err { background: var(--danger); }
#busy { position: absolute; inset: 0; background: rgba(255,255,255,.75); display: grid; place-content: center; justify-items: center; gap: 12px; z-index: 15; font-size: 14px; color: var(--muted); }
#busy[hidden] { display: none; }
.spinner { width: 30px; height: 30px; border: 3px solid var(--line); border-top-color: var(--accent); border-radius: 50%; animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 720px) {
  .info { order: 3; width: 100%; flex: none; }
  #find { width: 130px; }
  #side { width: 100%; top: auto; height: 55%; border-left: 0; border-top: 1px solid var(--line); }
}