:root {
  --bg: #0e0f13;
  --panel: #171922;
  --panel-2: #1e212c;
  --border: #2a2e3a;
  --text: #e7e9ee;
  --muted: #8b90a0;
  --accent: #6ea8fe;
  --accent-2: #4ade80;
  --danger: #f87171;
  --radius: 10px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 14px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Microsoft JhengHei", sans-serif;
  min-height: 100vh;
}
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; background: rgba(255,255,255,.06); padding: 1px 5px; border-radius: 5px; font-size: .9em; }
button { font: inherit; cursor: pointer; }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  gap: 16px; padding: 14px 22px; border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, #141620, #0e0f13);
  position: sticky; top: 0; z-index: 10;
}
.brand { display: flex; align-items: center; gap: 14px; }
.logo { font-size: 30px; color: var(--accent); }
.topbar h1 { font-size: 17px; margin: 0; }
.tagline { margin: 2px 0 0; color: var(--muted); font-size: 12.5px; }
.byline { margin: 3px 0 0; color: var(--muted); font-size: 12px; }
.byline strong { color: var(--text); }
.topbar-right { display: flex; align-items: center; gap: 16px; }
.settings { display: flex; gap: 14px; }
.settings label { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: 13px; }
.settings input { width: 68px; background: var(--panel-2); border: 1px solid var(--border); color: var(--text); border-radius: 7px; padding: 6px 8px; }

main { max-width: 1180px; margin: 0 auto; padding: 22px; }

.dropzone {
  border: 2px dashed var(--border); border-radius: 14px; padding: 42px 20px;
  text-align: center; background: var(--panel); transition: border-color .15s, background .15s;
}
.dropzone.drag { border-color: var(--accent); background: #1a2030; }
.drop-icon { font-size: 34px; color: var(--accent); }
.dropzone p { margin: 8px 0; }
.dropzone .hint { color: var(--muted); font-size: 12.5px; }
.link { background: none; border: none; color: var(--accent); text-decoration: underline; padding: 0; }

.workspace { margin-top: 20px; }
.file-tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.file-tab {
  padding: 7px 14px; border-radius: 8px; border: 1px solid var(--border);
  background: var(--panel); color: var(--muted); font-size: 13px;
}
.file-tab.active { color: var(--text); border-color: var(--accent); background: #1a2030; }
.file-tab .err { color: var(--danger); }

.preview-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.pane { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.pane-head { padding: 10px 14px; border-bottom: 1px solid var(--border); font-weight: 600; display: flex; align-items: baseline; gap: 10px; }
.pane-sub { color: var(--muted); font-weight: 400; font-size: 12px; }
.stage {
  aspect-ratio: 1 / 1; display: flex; align-items: center; justify-content: center;
  background-color: #12141c;
}
.stage.checker {
  background-image:
    linear-gradient(45deg, #2a2e3a 25%, transparent 25%),
    linear-gradient(-45deg, #2a2e3a 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #2a2e3a 75%),
    linear-gradient(-45deg, transparent 75%, #2a2e3a 75%);
  background-size: 18px 18px;
  background-position: 0 0, 0 9px, 9px -9px, -9px 0;
}
.stage svg, .stage canvas { max-width: 100%; max-height: 100%; display: block; }

.transport { display: flex; align-items: center; gap: 14px; margin: 16px 0; padding: 12px 14px; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); }
.transport input[type=range] { flex: 1; accent-color: var(--accent); }
.frame-label { color: var(--muted); font-variant-numeric: tabular-nums; min-width: 78px; text-align: right; }
.checker-toggle { color: var(--muted); font-size: 12.5px; display: flex; align-items: center; gap: 5px; }

.btn { background: var(--panel-2); border: 1px solid var(--border); color: var(--text); padding: 8px 16px; border-radius: 8px; }
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); color: #0b0d12; border-color: var(--accent); font-weight: 600; }
.btn.primary:hover { filter: brightness(1.08); }

.panels { display: grid; gap: 10px; margin-bottom: 18px; }
.panel { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); }
.panel > summary { cursor: pointer; padding: 12px 16px; font-weight: 600; list-style: none; }
.panel > summary::-webkit-details-marker { display: none; }
.panel > summary::before { content: "▸"; color: var(--muted); margin-right: 8px; }
.panel[open] > summary::before { content: "▾"; }
.panel-body { padding: 0 16px 16px; }
.muted { color: var(--muted); font-weight: 400; font-size: 12.5px; }

.diff-result { margin-top: 12px; }
.diff-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); gap: 10px; margin-top: 10px; }
.diff-cell { background: var(--panel-2); border: 1px solid var(--border); border-radius: 8px; padding: 8px; text-align: center; font-size: 12px; }
.diff-cell.bad { border-color: var(--danger); }
.diff-cell canvas { width: 100%; image-rendering: pixelated; border-radius: 4px; background: #000; }

.color-row, .rect-row { display: flex; align-items: center; gap: 12px; padding: 8px 0; border-bottom: 1px solid var(--border); }
.color-row:last-child, .rect-row:last-child { border-bottom: none; }
.swatch { width: 26px; height: 26px; border-radius: 6px; border: 1px solid var(--border); }
.color-row input[type=color] { width: 34px; height: 30px; padding: 0; border: none; background: none; }
.color-row .hex { font-family: ui-monospace, monospace; color: var(--muted); }
.color-row .kind, .rect-row .meta { color: var(--muted); font-size: 12px; }
.rect-row input[type=range] { flex: 1; accent-color: var(--accent); }
.rect-row .rval { min-width: 46px; text-align: right; font-variant-numeric: tabular-nums; }

.warn-item { padding: 6px 0; color: var(--muted); border-bottom: 1px solid var(--border); font-size: 12.5px; }
.warn-item:last-child { border-bottom: none; }

.actions { display: flex; align-items: center; gap: 12px; }

.sponsor {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 9px 18px; border-radius: 999px; text-decoration: none;
  color: #0b0d12; background: #4cc283; font-weight: 600; white-space: nowrap;
  box-shadow: 0 2px 10px rgba(76, 194, 131, .22);
}
.sponsor:hover { filter: brightness(1.08); }

@media (max-width: 720px) {
  .preview-grid { grid-template-columns: 1fr; }
  .topbar { flex-direction: column; align-items: flex-start; }
  .topbar-right { width: 100%; justify-content: space-between; }
}