:root {
  --bg-color: #ffffff;
  --grid-color: #f0f0f2;
  --text-color: #1d1d1f;
  --dock-bg: rgba(255, 255, 255, 0.85);
  --dock-border: #d1d1d6;
  --shadow: rgba(0, 0, 0, 0.08);
  --accent: #0071e3;
  --btn-hover: #e8e8ed;
  --adaptive-color: #000000;
}

body.dark {
  --bg-color: #121214;
  --grid-color: #1c1c1e;
  --text-color: #f5f5f7;
  --dock-bg: rgba(28, 28, 30, 0.85);
  --dock-border: #2c2c2e;
  --shadow: rgba(0, 0, 0, 0.3);
  --accent: #0a84ff;
  --btn-hover: #2c2c2e;
  --adaptive-color: #ffffff;
}

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

body, html {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-color);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--text-color);
  transition: background-color 0.2s ease, color 0.2s ease;
}

#whiteboard-canvas {
  display: block;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  cursor: crosshair;
}

#toolbar-container {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  transition: opacity 0.2s ease;
}

#toolbar {
  background: var(--dock-bg);
  border: 1px solid var(--dock-border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: 20px;
  padding: 8px 16px;
  display: flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 8px 32px var(--shadow);
}

button {
  background: transparent;
  border: none;
  cursor: pointer;
  font-size: 1.25rem;
  padding: 8px 12px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease, transform 0.1s ease;
}

button:hover {
  background: var(--btn-hover);
}

button:active {
  transform: scale(0.95);
}

button.active {
  background: var(--btn-hover);
  box-shadow: inset 0 0 0 1px var(--dock-border);
}

.divider {
  width: 1px;
  height: 24px;
  background: var(--dock-border);
  margin: 0 4px;
}

#settings-panel, #shapes-panel {
  background: var(--dock-bg);
  border: 1px solid var(--dock-border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: 16px;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: 0 8px 24px var(--shadow);
  transition: opacity 0.15s ease, transform 0.15s ease;
}

#shapes-panel {
  position: absolute;
  bottom: 90px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 9;
}

.hidden {
  display: none !important;
  opacity: 0;
  pointer-events: none;
}

.color-section, .size-section {
  display: flex;
  align-items: center;
  gap: 8px;
}

.color-btn {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  padding: 0;
  border: 2px solid transparent;
}

.color-btn.active {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--bg-color);
}

.color-btn[data-color="adaptive"] {
  background: conic-gradient(var(--adaptive-color) 0deg 180deg, var(--bg-color) 180deg 360deg);
  border: 1px solid var(--dock-border);
}

.size-btn {
  font-size: 0.85rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 6px;
}

.size-btn.active {
  background: var(--accent);
  color: white;
}

.shape-btn {
  font-size: 0.85rem;
  padding: 6px 12px;
  border-radius: 8px;
}

.shape-btn.active {
  background: var(--accent);
  color: white;
}