:root {
  /* Common Variables */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --transition: 0.2s ease;

  /* Light Theme (Default) */
  --bg-primary: #ffffff;
  --bg-secondary: #f4f4f5;
  --bg-tertiary: #e4e4e7;
  --bg-hover: #fafafa;
  --bg-selected: #f7f7f8;
  --card-bg: #ffffff;
  
  --text-primary: #18181b;
  --text-secondary: #52525b;
  --text-tertiary: #a1a1aa;
  
  --border: #e4e4e7;
  --input-bg: #ffffff;
  
  --primary: #18181b;
  --primary-hover: #3f3f46;
  --primary-fg: #ffffff;
  
  --danger: #ef5e5e;
  --success: #13c88c;
  --warning: #f59e0b;
  --modal-mask: rgba(0, 0, 0, 0.2);
}

[data-theme='dark'] {
  /* Dark Theme (Pure Black) */
  --bg-primary: #111111;
  --bg-secondary: #1e1e1e;
  --bg-tertiary: #27272a;
  --bg-hover: #161616;
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5), 0 4px 6px -4px rgb(0 0 0 / 0.5);
  --card-bg: #111111;
  
  --text-primary: #ffffff;
  --text-secondary: #a1a1aa;
  --text-tertiary: #52525b;
  
  --border: #3f3f3f;
  --input-bg: #000000;
  --bg-selected: #1a1a1a;
  
  --primary: #ffffff;
  --primary-hover: #e4e4e7;
  --primary-fg: #000000;
  --modal-mask: #23232333;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: background-color var(--transition), color var(--transition), border-color var(--transition);
}

/* Global transition for theme switching - low specificity to allow overrides */
* {
  transition: background-color var(--transition), color var(--transition), border-color var(--transition), box-shadow var(--transition);
}