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

body {
  font-family: "Segoe UI", "Microsoft YaHei", sans-serif;
  background-color: #eef3f8;
  color: #334155;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  text-align: center;
  padding: 16px;
  background-color: #dce7f2;
  border-bottom: 2px solid #b8c7d8;
}

header h1 {
  font-size: 1.25rem;
  color: #4777a8;
  letter-spacing: 2px;
}

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

.toolbar {
  width: 200px;
  background-color: #e5edf5;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  border-right: 2px solid #b8c7d8;
}

.canvas-container {
  flex: 1;
  min-width: 0;
  min-height: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 24px;
  overflow: auto;
}

canvas {
  border: 2px solid #9fb2c7;
  background-color: #ffffff;
  cursor: crosshair;
  flex-shrink: 0;
}

.tool-section {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.tool-section h3 {
  font-size: 0.85rem;
  letter-spacing: 1px;
  color: #64748b;
}

.tool-buttons {
  display: flex;
  gap: 6px;
}

.tool-btn {
  width: 48px;
  height: 48px;
  font-size: 1.4rem;
  border: 2px solid #b8c7d8;
  border-radius: 8px;
  background-color: #f8fbfe;
  color: #334155;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s;
}

.tool-btn:hover {
  background-color: #dce8f4;
}

.tool-btn.active {
  background-color: #4777a8;
  border-color: #4777a8;
  color: #ffffff;
}

.color-palette {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
}

.color-swatch {
  width: 100%;
  aspect-ratio: 1;
  border: 2px solid #b8c7d8;
  border-radius: 4px;
  cursor: pointer;
  transition: border-color 0.15s, transform 0.15s;
}

.color-swatch:hover {
  transform: scale(1.1);
}

.color-swatch.active {
  border-color: #4777a8;
  transform: scale(1.15);
}

.custom-color-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: #64748b;
  cursor: pointer;
}

.custom-color-label input[type="color"] {
  width: 36px;
  height: 28px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  background: none;
}

select {
  padding: 8px;
  border: 2px solid #b8c7d8;
  border-radius: 8px;
  background-color: #f8fbfe;
  color: #334155;
  font-size: 0.9rem;
  cursor: pointer;
}

.clear-btn,
.export-btn {
  padding: 12px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s;
}

.clear-btn {
  border: 2px solid #9fb2c7;
  background-color: #f8fbfe;
  color: #4777a8;
}

.clear-btn:hover {
  background-color: #dce8f4;
}

.export-btn {
  margin-top: auto;
  border: none;
  background-color: #4777a8;
  color: #ffffff;
}

.export-btn:hover {
  background-color: #3b638b;
}

@media (max-width: 640px) {
  main {
    flex-direction: column;
  }

  .toolbar {
    width: 100%;
    flex-direction: row;
    flex-wrap: wrap;
    border-right: none;
    border-bottom: 2px solid #b8c7d8;
    gap: 12px;
    padding: 12px;
  }

  .tool-section {
    flex-direction: row;
    align-items: center;
    gap: 8px;
  }

  .color-palette {
    grid-template-columns: repeat(8, 1fr);
  }

  .canvas-container {
    padding: 12px;
    justify-content: flex-start;
  }

  .clear-btn,
  .export-btn {
    margin-top: 0;
  }
}