:root {
  --rainbow: linear-gradient(to right, #e02020, #ff8c00, #ffd700, #22c55e, #3b82f6, #6366f1, #a855f7);
  --toolbar-bg: #f8fafc;
  --toolbar-border: #e2e8f0;
  --active-ring: #3b82f6;
  --group-bg: #eef2f7;
  --group-border: #d0d7e0;
  --btn-size: 44px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html, body { height: 100%; overflow: hidden; font-family: var(--font); }

body {
  display: flex;
  flex-direction: column;
  background: #ffffff;
}

header { flex: 0 0 auto; }

.rainbow-strip {
  height: 6px;
  background: var(--rainbow);
}

.title-bar {
  display: flex;
  justify-content: center;
  padding: 4px 0;
  background: var(--toolbar-bg);
}

.title-bar h1 {
  width: 75%;
  text-align: center;
  font-size: 20px;
  font-weight: 700;
  color: #334155;
  padding: 6px 0;
  background: linear-gradient(180deg, #fff 0%, #e8ecf1 100%);
  border: 1px solid var(--group-border);
  border-radius: 10px;
  box-shadow: inset 0 1px 0 #fff, 0 2px 4px rgba(0,0,0,0.12);
}

.title-bar h1 span {
  font-weight: 400;
  font-size: 15px;
  color: #64748b;
}

main {
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
}

canvas {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  cursor: crosshair;
  background: #ffffff;
}

.toolbar {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 6px 8px;
  padding-bottom: calc(6px + env(safe-area-inset-bottom, 0px));
  background: var(--toolbar-bg);
  border-top: 1px solid var(--toolbar-border);
  flex-wrap: wrap;
}

.tool-group {
  display: flex;
  align-items: center;
  gap: 4px;
  background: var(--group-bg);
  border: 1px solid var(--group-border);
  border-radius: 12px;
  padding: 4px 6px;
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.7), 0 1px 2px rgba(0,0,0,0.08);
}

.tool-btn, .size-btn, .shape-btn {
  width: var(--btn-size);
  height: var(--btn-size);
  border: 2px solid transparent;
  border-radius: 10px;
  background: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 6px;
}

.tool-btn svg {
  width: 100%;
  height: 100%;
  fill: #334155;
  stroke: #334155;
}

.tool-btn.active, .size-btn.active, .shape-btn.active {
  border-color: var(--active-ring);
  background: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.color-btn {
  width: 28px;
  height: 28px;
  border: 2px solid #cbd5e1;
  border-radius: 50%;
  cursor: pointer;
  padding: 0;
}

.color-btn.active {
  border-color: var(--active-ring);
  box-shadow: 0 0 0 2px var(--active-ring);
  transform: scale(1.15);
}

.color-btn[data-color="#ffffff"] { border-color: #94a3b8; }

.rainbow-btn { background: var(--rainbow) !important; }

.size-dot {
  display: block;
  border-radius: 50%;
  background: #334155;
}

.size-s { width: 6px; height: 6px; }
.size-m { width: 14px; height: 14px; }
.size-l { width: 24px; height: 24px; }

.shape-btn {
  font-size: 22px;
  line-height: 1;
  color: #334155;
}

.clear-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  z-index: 100;
}

.clear-overlay[hidden] { display: none; }

.clear-overlay p {
  font-size: 28px;
  font-weight: 700;
  color: #ffffff;
  font-family: var(--font);
}

.confirm-btn {
  width: 120px;
  height: 54px;
  border: none;
  border-radius: 14px;
  font-size: 22px;
  font-weight: 700;
  cursor: pointer;
  font-family: var(--font);
}

.confirm-btn.yes { background: #ef4444; color: #fff; }
.confirm-btn.no { background: #22c55e; color: #fff; }

@media (prefers-reduced-motion: no-preference) {
  .tool-btn, .color-btn, .size-btn, .shape-btn {
    transition: transform 100ms ease, border-color 100ms ease, background 100ms ease;
  }
  .tool-btn:active, .color-btn:active, .size-btn:active, .shape-btn:active {
    transform: scale(0.93);
  }
  .confirm-btn { transition: transform 100ms ease; }
  .confirm-btn:active { transform: scale(0.95); }
}