/* --------------------------------------------------------------------------
   Vercel Design System & Modern Web Standards — Digital Clock
   -------------------------------------------------------------------------- */

/* Standard Baseline color-scheme reflection */
:root {
  color-scheme: light dark;

  /* Cascades directly from the <meta name="color-scheme"> element */
  &:has(> head > meta[name="color-scheme"][content="dark"]) {
    color-scheme: dark;
  }
  &:has(> head > meta[name="color-scheme"][content="light"]) {
    color-scheme: light;
  }

  /* Color Palettes (Fallbacks + light-dark()) */
  --bg-page-light: #ffffff;
  --bg-page-dark: #000000;
  --bg-page: var(--bg-page-light);

  --text-primary-light: #000000;
  --text-primary-dark: #ededed;
  --text-primary: var(--text-primary-light);

  --text-secondary-light: #666666;
  --text-secondary-dark: #888888;
  --text-secondary: var(--text-secondary-light);

  --text-muted-light: #8e8e8e;
  --text-muted-dark: #555555;
  --text-muted: var(--text-muted-light);

  --border-subtle-light: #eaeaea;
  --border-subtle-dark: #222222;
  --border-subtle: var(--border-subtle-light);

  --border-strong-light: #d1d1d1;
  --border-strong-dark: #333333;
  --border-strong: var(--border-strong-light);

  --card-bg-light: rgba(255, 255, 255, 0.75);
  --card-bg-dark: rgba(10, 10, 10, 0.75);
  --card-bg: var(--card-bg-light);

  --card-inner-light: #f9f9f9;
  --card-inner-dark: #111111;
  --card-inner: var(--card-inner-light);

  --card-shadow-light: 0 4px 20px -2px rgba(0, 0, 0, 0.06), 0 2px 6px -1px rgba(0, 0, 0, 0.04);
  --card-shadow-dark: 0 8px 30px rgba(0, 0, 0, 0.8), 0 0 0 1px rgba(255, 255, 255, 0.07);
  --card-shadow: var(--card-shadow-light);

  --control-bg-light: #f3f3f3;
  --control-bg-dark: #181818;
  --control-bg: var(--control-bg-light);

  --control-active-light: #ffffff;
  --control-active-dark: #2a2a2a;
  --control-active: var(--control-active-light);

  --control-shadow-light: 0 1px 3px rgba(0, 0, 0, 0.1);
  --control-shadow-dark: 0 1px 3px rgba(0, 0, 0, 0.4);
  --control-shadow: var(--control-shadow-light);

  --dot-color-light: #e5e5e5;
  --dot-color-dark: #1a1a1a;
  --dot-color: var(--dot-color-light);

  --glow-color-light: rgba(0, 112, 243, 0.08);
  --glow-color-dark: rgba(0, 112, 243, 0.15);
  --glow-color: var(--glow-color-light);

  --accent-color: #0070f3;
  --accent-success: #0070f3;

  /* Font Families */
  --font-sans: 'Geist', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'Geist Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Smooth Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
}

/* Fallback for browsers supporting light-dark() natively */
@supports (color: light-dark(white, black)) {
  :root {
    --bg-page: light-dark(var(--bg-page-light), var(--bg-page-dark));
    --text-primary: light-dark(var(--text-primary-light), var(--text-primary-dark));
    --text-secondary: light-dark(var(--text-secondary-light), var(--text-secondary-dark));
    --text-muted: light-dark(var(--text-muted-light), var(--text-muted-dark));
    --border-subtle: light-dark(var(--border-subtle-light), var(--border-subtle-dark));
    --border-strong: light-dark(var(--border-strong-light), var(--border-strong-dark));
    --card-bg: light-dark(var(--card-bg-light), var(--card-bg-dark));
    --card-inner: light-dark(var(--card-inner-light), var(--card-inner-dark));
    --card-shadow: light-dark(var(--card-shadow-light), var(--card-shadow-dark));
    --control-bg: light-dark(var(--control-bg-light), var(--control-bg-dark));
    --control-active: light-dark(var(--control-active-light), var(--control-active-dark));
    --control-shadow: light-dark(var(--control-shadow-light), var(--control-shadow-dark));
    --dot-color: light-dark(var(--dot-color-light), var(--dot-color-dark));
    --glow-color: light-dark(var(--glow-color-light), var(--glow-color-dark));
  }
}

/* Fallback when prefers-color-scheme is dark and no light-dark() */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg-page: var(--bg-page-dark);
    --text-primary: var(--text-primary-dark);
    --text-secondary: var(--text-secondary-dark);
    --text-muted: var(--text-muted-dark);
    --border-subtle: var(--border-subtle-dark);
    --border-strong: var(--border-strong-dark);
    --card-bg: var(--card-bg-dark);
    --card-inner: var(--card-inner-dark);
    --card-shadow: var(--card-shadow-dark);
    --control-bg: var(--control-bg-dark);
    --control-active: var(--control-active-dark);
    --control-shadow: var(--control-shadow-dark);
    --dot-color: var(--dot-color-dark);
    --glow-color: var(--glow-color-dark);
  }
}

/* Explicit data-theme dark override */
:root[data-theme="dark"] {
  --bg-page: var(--bg-page-dark);
  --text-primary: var(--text-primary-dark);
  --text-secondary: var(--text-secondary-dark);
  --text-muted: var(--text-muted-dark);
  --border-subtle: var(--border-subtle-dark);
  --border-strong: var(--border-strong-dark);
  --card-bg: var(--card-bg-dark);
  --card-inner: var(--card-inner-dark);
  --card-shadow: var(--card-shadow-dark);
  --control-bg: var(--control-bg-dark);
  --control-active: var(--control-active-dark);
  --control-shadow: var(--control-shadow-dark);
  --dot-color: var(--dot-color-dark);
  --glow-color: var(--glow-color-dark);
}

/* Explicit data-theme light override */
:root[data-theme="light"] {
  --bg-page: var(--bg-page-light);
  --text-primary: var(--text-primary-light);
  --text-secondary: var(--text-secondary-light);
  --text-muted: var(--text-muted-light);
  --border-subtle: var(--border-subtle-light);
  --border-strong: var(--border-strong-light);
  --card-bg: var(--card-bg-light);
  --card-inner: var(--card-inner-light);
  --card-shadow: var(--card-shadow-light);
  --control-bg: var(--control-bg-light);
  --control-active: var(--control-active-light);
  --control-shadow: var(--control-shadow-light);
  --dot-color: var(--dot-color-light);
  --glow-color: var(--glow-color-light);
}

/* --------------------------------------------------------------------------
   Base & Resets
   -------------------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

html, body {
  min-height: 100vh;
  background-color: var(--bg-page);
  color: var(--text-primary);
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color 0.25s cubic-bezier(0.16, 1, 0.3, 1),
              color 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  overflow-x: hidden;
}

/* View Transition API Polish for Theme Switching */
::view-transition-old(root),
::view-transition-new(root) {
  animation-duration: 0.3s;
  animation-timing-function: cubic-bezier(0.16, 1, 0.3, 1);
}

/* Background Vercel Grid Pattern */
.bg-grid-pattern {
  position: fixed;
  inset: 0;
  background-image: radial-gradient(var(--dot-color) 1px, transparent 1px);
  background-size: 24px 24px;
  opacity: 0.8;
  pointer-events: none;
  z-index: 0;
}

/* Ambient Radial Glow */
.ambient-glow {
  position: fixed;
  top: -120px;
  left: 50%;
  transform: translateX(-50%);
  width: 650px;
  height: 400px;
  background: radial-gradient(circle, var(--glow-color) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
  filter: blur(40px);
}

/* Container */
.app-container {
  position: relative;
  z-index: 1;
  max-width: 900px;
  margin: 0 auto;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  padding: 1.5rem 1.25rem 2rem;
  justify-content: space-between;
}

/* --------------------------------------------------------------------------
   Header & Vercel Logo
   -------------------------------------------------------------------------- */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 2rem;
}

.header-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.prometrion-logo-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: #000000;
  border: 1px solid var(--border-subtle);
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), 
              border-color 0.2s ease,
              box-shadow 0.2s ease;
  user-select: none;
}

.prometrion-logo-wrapper:hover {
  transform: scale(1.06);
  border-color: var(--border-strong);
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.16);
}

.prometrion-logo-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.brand-text {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.brand-title {
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.brand-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: #10b981; /* Live green pulse */
  box-shadow: 0 0 8px rgba(16, 185, 129, 0.6);
  animation: pulse-dot 2s infinite ease-in-out;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.85); }
}

/* --------------------------------------------------------------------------
   Header Actions & About Button
   -------------------------------------------------------------------------- */
.header-actions {
  display: flex;
  align-items: center;
}

/* --------------------------------------------------------------------------
   Vercel-style Segmented Theme Switcher Control
   -------------------------------------------------------------------------- */
.theme-switch-container {
  display: flex;
  align-items: center;
}

.theme-segmented-control {
  position: relative;
  display: flex;
  align-items: center;
  background-color: var(--control-bg);
  border: 1px solid var(--border-subtle);
  padding: 3px;
  border-radius: var(--radius-full);
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.04);
}

.theme-pill-indicator {
  position: absolute;
  top: 3px;
  bottom: 3px;
  left: 3px;
  background-color: var(--control-active);
  border-radius: var(--radius-full);
  box-shadow: var(--control-shadow);
  transition: transform 0.22s cubic-bezier(0.16, 1, 0.3, 1),
              width 0.22s cubic-bezier(0.16, 1, 0.3, 1);
  pointer-events: none;
  z-index: 1;
}

.theme-btn {
  position: relative;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 28px;
  padding: 0;
  font-family: var(--font-sans);
  color: var(--text-secondary);
  background: transparent;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: color 0.15s ease;
  user-select: none;
}

.theme-btn svg {
  display: block;
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.theme-btn:hover {
  color: var(--text-primary);
}

.theme-btn:hover svg {
  transform: scale(1.08);
}

.theme-btn[aria-checked="true"] {
  color: var(--text-primary);
  font-weight: 600;
}

.theme-btn:focus-visible {
  outline: 2px solid var(--text-primary);
  outline-offset: 2px;
}

/* --------------------------------------------------------------------------
   Clock Main Surface Card
   -------------------------------------------------------------------------- */
.clock-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 1.5rem;
  margin: 1.5rem 0;
}

.clock-card {
  position: relative;
  background: var(--card-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem 2rem;
  box-shadow: var(--card-shadow);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.clock-card:hover {
  border-color: var(--border-strong);
}

/* Meta Bar inside Card */
.card-meta-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
}

.meta-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.3rem 0.65rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.meta-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.icon-button {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.65rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
}

.icon-button:hover {
  background: var(--control-active);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.icon-button:focus-visible {
  outline: 2px solid var(--text-primary);
  outline-offset: 1px;
}

/* --------------------------------------------------------------------------
   Primary Clock Face Display
   -------------------------------------------------------------------------- */
.clock-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 1.5rem 0;
  user-select: none;
}

.time-digit-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.digit-box {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  min-width: 130px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.05);
  transition: all 0.2s ease;
}

.digit-box:hover {
  border-color: var(--border-strong);
}

.digit-value {
  font-family: var(--font-mono);
  font-size: 5rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.04em;
  font-variant-numeric: tabular-nums lining-nums;
  color: var(--text-primary);
}

.digit-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  color: var(--text-muted);
}

/* Pulsing Colon Separator */
.time-separator {
  font-family: var(--font-mono);
  font-size: 4rem;
  font-weight: 300;
  color: var(--text-secondary);
  line-height: 1;
  margin-bottom: 1.4rem;
  animation: colon-pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

@keyframes colon-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

/* Seconds & Period Item Visibility Toggles */
.seconds-item.hidden,
.period-item.hidden {
  display: none !important;
}

/* --------------------------------------------------------------------------
   Date Display
   -------------------------------------------------------------------------- */
.date-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.65rem;
  margin-top: 1.25rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
}

.calendar-icon {
  color: var(--text-secondary);
  display: flex;
  align-items: center;
}

.full-date-text {
  font-size: 1.1rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

.week-number-badge {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.15rem 0.45rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Progress Meter (Day Elapsed)
   -------------------------------------------------------------------------- */
.progress-section {
  padding-top: 1.5rem;
}

.progress-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.progress-title {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.progress-percent {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

.progress-track {
  width: 100%;
  height: 6px;
  background: var(--control-bg);
  border-radius: var(--radius-full);
  overflow: hidden;
  border: 1px solid var(--border-subtle);
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--text-primary);
  border-radius: var(--radius-full);
  transition: width 0.4s ease;
}

/* --------------------------------------------------------------------------
   World Time Quick Chips
   -------------------------------------------------------------------------- */
.world-time-section {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1.5rem;
  padding-top: 1.25rem;
  border-top: 1px dashed var(--border-subtle);
  flex-wrap: wrap;
}

.world-time-label {
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.tz-chips-group {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
}

.tz-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.3rem 0.75rem;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 500;
  border: 1px solid var(--border-subtle);
  background: var(--control-bg);
  color: var(--text-secondary);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all 0.15s ease;
  user-select: none;
}

.tz-chip:hover {
  color: var(--text-primary);
  border-color: var(--border-strong);
  background: var(--control-active);
}

.tz-chip.active {
  background: var(--text-primary);
  color: var(--bg-page);
  border-color: var(--text-primary);
  font-weight: 600;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12);
}

.tz-chip:focus-visible {
  outline: 2px solid var(--text-primary);
  outline-offset: 1px;
}

/* --------------------------------------------------------------------------
   Toolbar Controls
   -------------------------------------------------------------------------- */
.controls-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 0.85rem 1.25rem;
  background: var(--card-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  backdrop-filter: blur(10px);
}

.control-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.control-label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-secondary);
}

/* Segmented Mini (12h / 24h) */
.segmented-mini {
  display: flex;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 2px;
}

.mini-btn {
  background: transparent;
  border: none;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.25rem 0.55rem;
  border-radius: calc(var(--radius-sm) - 2px);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.mini-btn.active {
  background: var(--control-active);
  color: var(--text-primary);
  box-shadow: var(--control-shadow);
}

/* Toggle Switch Component */
.toggle-switch {
  position: relative;
  width: 36px;
  height: 20px;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: background-color 0.2s ease, border-color 0.2s ease;
  padding: 0;
}

.toggle-switch.active {
  background: var(--text-primary);
  border-color: var(--text-primary);
}

.switch-handle {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 14px;
  height: 14px;
  background: var(--text-secondary);
  border-radius: 50%;
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), background-color 0.2s ease;
}

.toggle-switch.active .switch-handle {
  transform: translateX(16px);
  background: var(--bg-page);
}

/* Shortcuts Hint */
.shortcuts-hint {
  display: flex;
  gap: 0.5rem;
  margin-left: auto;
}

.kbd-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.72rem;
  color: var(--text-muted);
}

kbd {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  padding: 0.1rem 0.35rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--text-secondary);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.1);
}

/* --------------------------------------------------------------------------
   Standard Prometrion Universal Footer (Section 10)
   -------------------------------------------------------------------------- */
.app-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1.5rem;
  font-size: 0.78rem;
  color: var(--text-secondary);
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-branding {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.prometrion-branding-block {
  display: flex;
  flex-direction: column;
  gap: 0.18rem;
}

.brand-attribution,
.dev-attribution {
  font-size: 0.76rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.4;
}

.prometrion-link {
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 600;
  transition: opacity 0.15s ease;
}

.prometrion-link:hover {
  text-decoration: underline;
  opacity: 0.85;
}

.footer-right {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.footer-about-link,
.footer-details-link {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.76rem;
  font-weight: 500;
  cursor: pointer;
  padding: 0;
  text-decoration: none;
  transition: color 0.15s ease;
}

.footer-about-link:hover,
.footer-details-link:hover {
  color: var(--text-primary);
  text-decoration: underline;
}

.footer-separator {
  color: var(--text-muted);
}

.footer-status {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Universal About Screen Modal Specification (Section 17)
   -------------------------------------------------------------------------- */
dialog.about-dialog {
  border: none;
  padding: 0;
  background: transparent;
  max-width: 440px;
  width: 90vw;
  margin: auto;
  border-radius: var(--radius-lg);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.4), 0 0 0 1px var(--border-subtle);
  overflow: visible;
}

dialog.about-dialog::backdrop {
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  animation: backdrop-fade-in 0.2s ease forwards;
}

@keyframes backdrop-fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

.about-card-surface {
  background: var(--card-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.5rem;
  color: var(--text-primary);
  display: flex;
  flex-direction: column;
  animation: dialog-pop 0.22s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes dialog-pop {
  from {
    opacity: 0;
    transform: scale(0.96) translateY(10px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

.about-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.about-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--text-muted);
  padding: 0.2rem 0.5rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
}

.about-close-btn {
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.about-close-btn:hover {
  background: var(--control-active);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.about-identity {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.5rem;
  padding: 0.5rem 0 0.8rem;
}

.about-icon-wrapper {
  width: 64px;
  height: 64px;
  border-radius: var(--radius-md);
  background: #000000;
  border: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.15);
}

.about-icon-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.about-app-name {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin: 0;
}

.about-app-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin: 0;
  max-width: 320px;
  line-height: 1.45;
}

.about-version-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.65rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-secondary);
  font-weight: 500;
  margin-top: 0.2rem;
}

.version-sep {
  color: var(--text-muted);
}

.about-divider {
  height: 1px;
  background: var(--border-subtle);
  margin: 1rem 0;
}

.about-attribution-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.35rem;
}

.about-product-of,
.about-built-by {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.4;
}

.about-nav-links {
  display: flex;
  gap: 0.6rem;
  margin-top: 0.6rem;
}

.about-nav-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-primary);
  text-decoration: none;
  padding: 0.35rem 0.75rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  transition: all 0.15s ease;
}

.about-nav-link:hover {
  background: var(--control-active);
  border-color: var(--border-strong);
  transform: translateY(-1px);
}

.about-copyright-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.15rem;
}

.about-company-sub {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0;
}

.about-tagline {
  font-size: 0.72rem;
  color: var(--text-muted);
  margin: 0;
}

.about-copyright-text {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

/* --------------------------------------------------------------------------
   Toast Notifications
   -------------------------------------------------------------------------- */
.toast-container {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  pointer-events: none;
}

.toast {
  background: var(--card-inner);
  color: var(--text-primary);
  border: 1px solid var(--border-strong);
  padding: 0.6rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 500;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  opacity: 0;
  transform: translateY(10px);
  animation: toast-in 0.2s ease forwards;
}

@keyframes toast-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.toast.toast-out {
  animation: toast-out 0.2s ease forwards;
}

@keyframes toast-out {
  to {
    opacity: 0;
    transform: translateY(-8px);
  }
}

/* --------------------------------------------------------------------------
   Fullscreen Mode Styles
   -------------------------------------------------------------------------- */
:fullscreen .app-container,
html.is-fullscreen .app-container {
  max-width: 100vw;
  height: 100vh;
  padding: 2.5rem 3rem;
  justify-content: center;
}

:fullscreen .clock-card,
html.is-fullscreen .clock-card {
  border: none;
  background: transparent;
  box-shadow: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
}

:fullscreen .card-meta-bar,
html.is-fullscreen .card-meta-bar {
  margin-bottom: 0;
  width: 100%;
}

:fullscreen .digit-value,
html.is-fullscreen .digit-value {
  font-size: 9rem;
}

:fullscreen .digit-box,
html.is-fullscreen .digit-box {
  min-width: 220px;
  padding: 2rem 2.5rem;
}

:fullscreen .time-separator,
html.is-fullscreen .time-separator {
  font-size: 7rem;
}



:fullscreen .date-display,
html.is-fullscreen .date-display {
  border-bottom: none;
  padding-bottom: 0;
  margin-top: 2rem;
}

:fullscreen .full-date-text,
html.is-fullscreen .full-date-text {
  font-size: 1.4rem;
}

/* Exit fullscreen button positioned unobtrusively in top-right corner */
:fullscreen .meta-actions,
html.is-fullscreen .meta-actions {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  z-index: 50;
  opacity: 0;
  transition: opacity 0.25s ease;
}

:fullscreen:hover .meta-actions,
html.is-fullscreen:hover .meta-actions,
:fullscreen .meta-actions:focus-within,
html.is-fullscreen .meta-actions:focus-within {
  opacity: 1;
}

@media (hover: none) {
  :fullscreen .meta-actions,
  html.is-fullscreen .meta-actions {
    opacity: 0.4;
  }
}

/* Hide Day Elapsed bar, Timezone tag, Toolbar, Header, Footer & World Time chips */
:fullscreen #timezoneBadge,
html.is-fullscreen #timezoneBadge,
:fullscreen .progress-section,
html.is-fullscreen .progress-section,
:fullscreen .world-time-section,
html.is-fullscreen .world-time-section,
:fullscreen .controls-toolbar,
html.is-fullscreen .controls-toolbar,
:fullscreen .app-header,
html.is-fullscreen .app-header,
:fullscreen .app-footer,
html.is-fullscreen .app-footer,
:fullscreen .knowledge-screen,
html.is-fullscreen .knowledge-screen {
  display: none !important;
}

/* --------------------------------------------------------------------------
   Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 768px) {
  .clock-display {
    gap: 0.35rem;
  }

  .digit-box {
    min-width: 80px;
    padding: 0.75rem 0.6rem;
  }

  .digit-value {
    font-size: 3rem;
  }

  .time-separator {
    font-size: 2.5rem;
    margin-bottom: 0.8rem;
  }



  .clock-card {
    padding: 1.5rem 1.25rem;
  }

  .shortcuts-hint {
    display: none;
  }

  .theme-label {
    display: none; /* Icon-only in compact screens */
  }

  .theme-btn {
    padding: 0.4rem 0.55rem;
  }
}

@media (max-width: 480px) {
  .digit-box {
    min-width: 62px;
    padding: 0.5rem 0.4rem;
  }

  .digit-value {
    font-size: 2.2rem;
  }

  .time-separator {
    font-size: 1.8rem;
    margin-bottom: 0.6rem;
  }

  .full-date-text {
    font-size: 0.95rem;
  }

  .app-header {
    flex-wrap: wrap;
    gap: 0.75rem;
  }
}

/* Reduced Motion Preference */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* --------------------------------------------------------------------------
   Knowledge Screen (Appearing beneath the footer on scroll)
   -------------------------------------------------------------------------- */
.knowledge-screen {
  position: relative;
  z-index: 1;
  width: 100%;
  border-top: 1px solid var(--border-subtle);
  background: var(--bg-page);
  padding: 5rem 1.5rem 6.5rem;
}

.knowledge-container {
  max-width: 900px;
  margin: 0 auto;
}

/* Knowledge Hero */
.knowledge-hero {
  padding-bottom: 3.5rem;
  border-bottom: 1px solid var(--border-subtle);
  margin-bottom: 3.5rem;
}

.knowledge-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.badge-pill {
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.knowledge-main-title {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

.knowledge-lead {
  font-size: 1.08rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.knowledge-lead strong {
  color: var(--text-primary);
}

.seo-link {
  color: var(--accent-color);
  text-decoration: none;
  border-bottom: 1px dotted currentColor;
  transition: opacity 0.15s ease;
}

.seo-link:hover {
  opacity: 0.8;
  text-decoration: underline;
}

.knowledge-action-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
}

.knowledge-about-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--text-primary);
  color: var(--bg-page);
  padding: 0.65rem 1.15rem;
  border-radius: var(--radius-full);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1), transform 0.2s ease;
}

.knowledge-about-btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.knowledge-secondary-btn {
  display: inline-flex;
  align-items: center;
  padding: 0.65rem 1.1rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 0.85rem;
  font-weight: 500;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.knowledge-secondary-btn:hover {
  background: var(--control-active);
  border-color: var(--border-strong);
}

/* Knowledge Blocks */
.knowledge-block {
  margin-bottom: 4rem;
}

.block-header {
  margin-bottom: 2rem;
}

.block-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  color: var(--accent-color);
  margin-bottom: 0.5rem;
}

.block-title {
  font-size: 1.65rem;
  font-weight: 600;
  letter-spacing: -0.025em;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.block-subtitle {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

/* Feature Grid (How it works) */
.knowledge-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.feature-card {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.6rem 1.4rem;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.feature-card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
}

.card-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.card-title {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
}

.card-text {
  font-size: 0.88rem;
  line-height: 1.65;
  color: var(--text-secondary);
}

.card-text code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 0.15rem 0.35rem;
  border-radius: 4px;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
}

/* Use Case Grid */
.use-case-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.use-case-item {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.5rem 1.4rem;
  border-left: 3px solid var(--border-strong);
}

.use-case-item h4 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.use-case-item p {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.use-case-item strong {
  color: var(--text-primary);
}

.use-case-item kbd {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.15rem 0.4rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--text-primary);
}

/* FAQ Accordion */
.faq-accordion {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.faq-item {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.faq-item:hover {
  border-color: var(--border-strong);
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.15rem 1.35rem;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  user-select: none;
  list-style: none;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-chevron {
  color: var(--text-muted);
  transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  flex-shrink: 0;
  margin-left: 1rem;
}

.faq-item[open] .faq-chevron {
  transform: rotate(180deg);
  color: var(--text-primary);
}

.faq-item[open] .faq-question {
  border-bottom: 1px solid var(--border-subtle);
}

.faq-answer {
  padding: 1.15rem 1.35rem 1.35rem;
  font-size: 0.9rem;
  line-height: 1.65;
  color: var(--text-secondary);
}

.faq-answer code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 0.15rem 0.35rem;
  border-radius: 4px;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
}

.faq-answer kbd {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.15rem 0.4rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
   Search Clusters Grid (People Also Search For)
   -------------------------------------------------------------------------- */
.search-clusters-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.search-cluster-card {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.5rem 1.4rem;
  display: flex;
  flex-direction: column;
  transition: border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.search-cluster-card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
}

.search-cluster-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.85rem;
}

.search-query-badge {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.search-cluster-icon {
  color: var(--text-muted);
  flex-shrink: 0;
}

.search-query-title {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--text-primary);
  margin-bottom: 0.65rem;
  line-height: 1.35;
}

.search-query-desc {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-secondary);
  margin-bottom: 1.1rem;
  flex-grow: 1;
}

.search-query-desc kbd {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.15rem 0.4rem;
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--text-primary);
}

.search-query-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: auto;
  padding-top: 0.85rem;
  border-top: 1px dashed var(--border-subtle);
}

.search-tag {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 500;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
}

/* Privacy Card */
.privacy-card {
  background: var(--card-inner);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem;
}

.privacy-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.75rem;
}

.privacy-shield-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: rgba(0, 112, 243, 0.1);
  color: var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.privacy-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}

.privacy-subtitle {
  font-size: 0.82rem;
  color: var(--text-muted);
}

.privacy-points-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin-bottom: 1.75rem;
}

.privacy-point {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
}

.point-check {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: rgba(16, 185, 129, 0.15);
  color: #10b981;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 0.1rem;
}

.privacy-point strong {
  display: block;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.privacy-point p {
  font-size: 0.84rem;
  line-height: 1.55;
  color: var(--text-secondary);
}

.privacy-footer-note {
  border-top: 1px solid var(--border-subtle);
  padding-top: 1.25rem;
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

/* Knowledge Bottom Bar */
.knowledge-bottom-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 2.5rem;
  border-top: 1px solid var(--border-subtle);
}

.bottom-brand-info {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.bottom-copyright {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.back-to-top-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1rem;
  border-radius: var(--radius-full);
  background: var(--control-bg);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.back-to-top-btn:hover {
  background: var(--control-active);
  color: var(--text-primary);
  border-color: var(--border-strong);
  transform: translateY(-2px);
}

/* Knowledge Responsive Media Queries */
@media (max-width: 768px) {
  .knowledge-grid,
  .use-case-grid,
  .search-clusters-grid,
  .privacy-points-grid {
    grid-template-columns: 1fr;
  }

  .knowledge-main-title {
    font-size: 1.8rem;
  }

  .knowledge-screen {
    padding: 3.5rem 1rem 5rem;
  }

  .knowledge-bottom-bar {
    flex-direction: column;
    align-items: flex-start;
    gap: 1.5rem;
  }
}