/* ==========================================================================
   Theme Toggle System
   Dark theme (default) / Light theme via [data-theme="light"]
   ========================================================================== */

:root {
  /* --- Dark Theme (Default) --- */
  --bg-primary: #1a1a2e;
  --bg-secondary: #282c34;
  --bg-tertiary: #2d3748;
  --bg-code: #1e1e2e;
  --bg-hover: rgba(255, 255, 255, 0.06);
  --bg-card: #22223b;

  --text-primary: #e0e0e0;
  --text-secondary: #a0aec0;
  --text-muted: #718096;
  --text-inverse: #1a1a2e;

  --accent: #61dafb;
  --accent-hover: #79e3ff;
  --accent-muted: rgba(97, 218, 251, 0.15);

  --border-color: rgba(255, 255, 255, 0.1);
  --border-color-strong: rgba(255, 255, 255, 0.2);

  --success: #4ecdc4;
  --success-bg: rgba(78, 205, 196, 0.15);
  --error: #e94560;
  --error-bg: rgba(233, 69, 96, 0.15);
  --warning: #f5a623;
  --warning-bg: rgba(245, 166, 35, 0.15);

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace;

  --transition-colors: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease,
    box-shadow 0.3s ease;
}

/* --- Light Theme Overrides --- */
[data-theme="light"] {
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f5;
  --bg-tertiary: #e8edf2;
  --bg-code: #f0f2f5;
  --bg-hover: rgba(0, 0, 0, 0.04);
  --bg-card: #ffffff;

  --text-primary: #333333;
  --text-secondary: #555555;
  --text-muted: #888888;
  --text-inverse: #ffffff;

  --accent: #087ea4;
  --accent-hover: #065d7a;
  --accent-muted: rgba(8, 126, 164, 0.12);

  --border-color: rgba(0, 0, 0, 0.1);
  --border-color-strong: rgba(0, 0, 0, 0.2);

  --success: #2a9d8f;
  --success-bg: rgba(42, 157, 143, 0.12);
  --error: #d63031;
  --error-bg: rgba(214, 48, 49, 0.1);
  --warning: #e17055;
  --warning-bg: rgba(225, 112, 85, 0.1);

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
}

/* --- Smooth Transitions on Theme Change --- */
body,
.sidebar,
.sidebar-nav,
.content,
.markdown-section,
.app-nav,
.search,
.progress-bar-container,
.progress-dropdown,
.quiz-container,
.compare-container,
.playground-container,
.flexbox-playground {
  transition: var(--transition-colors);
}

/* ==========================================================================
   Theme Toggle Button
   ========================================================================== */

.theme-toggle-btn {
  position: absolute;
  top: 48px;
  right: 12px;
  z-index: 50;
  width: 32px;
  height: 32px;
  padding: 0;
  border: 1px solid var(--border-color, rgba(255, 255, 255, 0.1));
  border-radius: 50%;
  background: var(--bg-tertiary, #2d3748);
  color: var(--text-secondary, #a0aec0);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.3s ease, border-color 0.3s ease, transform 0.2s ease,
    box-shadow 0.2s ease;
  -webkit-appearance: none;
  appearance: none;
  outline: none;
}

.theme-toggle-btn:hover {
  background: var(--bg-hover, rgba(255, 255, 255, 0.06));
  border-color: var(--accent, #61dafb);
  box-shadow: 0 0 8px var(--accent-muted, rgba(97, 218, 251, 0.15));
  transform: scale(1.1);
}

.theme-toggle-btn:active {
  transform: scale(0.95);
}

.theme-toggle-btn:focus-visible {
  outline: 2px solid var(--accent, #61dafb);
  outline-offset: 2px;
}

/* Icon states */
.theme-toggle-btn .icon-sun,
.theme-toggle-btn .icon-moon {
  display: none;
  pointer-events: none;
}

/* Dark mode: show sun icon (to switch to light) */
:root:not([data-theme="light"]) .theme-toggle-btn .icon-sun,
html:not([data-theme="light"]) .theme-toggle-btn .icon-sun {
  display: inline;
}

/* Light mode: show moon icon (to switch to dark) */
[data-theme="light"] .theme-toggle-btn .icon-moon {
  display: inline;
}
[data-theme="light"] .theme-toggle-btn .icon-sun {
  display: none;
}