:root {
  --bg: #0f1115;
  --panel: #171a21;
  --panel-2: #1d2129;
  --line: #2a2f3a;
  --text: #e6e8ee;
  --muted: #9aa2b1;
  --accent: #5aa9ff;
  --accent-soft: rgba(90, 169, 255, .14);
  --radius: 12px;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f7f9;
    --panel: #ffffff;
    --panel-2: #f0f2f6;
    --line: #dfe3ea;
    --text: #171a21;
    --muted: #666e7d;
    --accent: #1f6feb;
    --accent-soft: rgba(31, 111, 235, .10);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  padding: 40px 20px 64px;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header { text-align: center; margin-bottom: 28px; }
h1 { margin: 0; font-size: 22px; font-weight: 600; letter-spacing: -.01em; }
.sub { margin: 6px 0 0; color: var(--muted); font-size: 14px; max-width: 48ch; }

main { width: 100%; max-width: 720px; }

/* ---- dropzone ---- */
#dropzone {
  border: 1.5px dashed var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: border-color .15s, background .15s, transform .15s;
  outline: none;
}
#dropzone:hover, #dropzone:focus-visible { border-color: var(--accent); }
#dropzone.dragover {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: scale(1.005);
}
.dz-icon { width: 40px; height: 40px; color: var(--muted); margin-bottom: 10px; }
#dropzone.dragover .dz-icon { color: var(--accent); }
.dz-text { margin: 0; font-weight: 500; }
.dz-text span { color: var(--muted); font-weight: 400; }
.dz-hint { margin: 6px 0 0; color: var(--muted); font-size: 12px; letter-spacing: .06em; text-transform: uppercase; }

.status { min-height: 20px; margin: 12px 0 0; text-align: center; font-size: 13px; color: var(--muted); }
.status.error { color: #ff6b6b; }

/* ---- result ---- */
#result { margin-top: 20px; }

.stage {
  background:
    linear-gradient(45deg, var(--panel-2) 25%, transparent 25%, transparent 75%, var(--panel-2) 75%) 0 0 / 20px 20px,
    linear-gradient(45deg, var(--panel-2) 25%, transparent 25%, transparent 75%, var(--panel-2) 75%) 10px 10px / 20px 20px,
    var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  justify-content: center;
}

.canvas-wrap { position: relative; line-height: 0; max-width: 100%; }
.canvas-wrap canvas {
  display: block;
  max-width: 100%;
  max-height: 60vh;
  width: auto;
  height: auto;
  image-rendering: auto;
}
/* Tiny outputs are unreadable at 1:1, so scale them up crisply. */
.canvas-wrap.zoom canvas { width: 320px; image-rendering: pixelated; }

.overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}
.overlay circle {
  fill: none;
  stroke: var(--accent);
  stroke-width: .5;
  vector-effect: non-scaling-stroke;
}
.overlay line {
  stroke: var(--accent);
  stroke-width: .5;
  stroke-dasharray: 4 4;
  opacity: .45;
  vector-effect: non-scaling-stroke;
}
.overlay.hidden { display: none; }

.panel {
  margin-top: 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: flex-end;
  justify-content: space-between;
}

.stats { display: grid; grid-template-columns: repeat(2, auto); gap: 8px 28px; margin: 0; }
.stats dt { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .06em; }
.stats dd { margin: 2px 0 0; font-variant-numeric: tabular-nums; font-size: 14px; }

.actions { display: flex; align-items: center; gap: 10px; }

button {
  font: inherit;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--text);
  cursor: pointer;
  transition: filter .15s, border-color .15s;
}
button:hover { filter: brightness(1.12); border-color: var(--accent); }
button.primary { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 500; }

.toggle { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: 13px; cursor: pointer; user-select: none; }
.toggle input { accent-color: var(--accent); }

@media (max-width: 560px) {
  .panel { flex-direction: column; align-items: stretch; }
  .actions { justify-content: stretch; }
  .actions button { flex: 1; }
}