/* ==================== BASE ==================== */
:root {
  --bg-primary: #05070a;
  --bg-secondary: #0d1118;
  --bg-tertiary: #141a24;
  --bg-card: #101622;
  --text-primary: #e4f6ff;
  --text-secondary: #7aa4b8;
  --text-muted: #4a6270;
  --accent-primary: #00d4ff;
  --accent-dim: #007a99;
  --danger: #ff5577;
  --focus-ring: #00d4ff;
  --focus-glow: rgba(0, 212, 255, 0.4);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  width: 600px;
  height: 600px;
  overflow: hidden;
}

#app { width: 100%; height: 100%; position: relative; }

/* --- Screens --- */
.screen {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  position: absolute;
  top: 0;
  left: 0;
}
.screen.hidden { display: none; }

/* --- Header --- */
.header {
  display: flex;
  align-items: center;
  padding: 16px 20px;
  background: var(--bg-secondary);
  gap: 12px;
  flex-shrink: 0;
}
.header h1 { font-size: 22px; font-weight: 600; flex: 1; }
.header-meta { font-size: 13px; color: var(--text-secondary); }
.back-btn {
  background: transparent;
  color: var(--text-primary);
  font-size: 22px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
}

/* --- Content --- */
.content {
  flex: 1;
  padding: 16px 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

/* --- Focus States --- */
.focusable {
  transition: all 0.15s ease;
  border: 2px solid transparent;
  cursor: pointer;
  min-height: 44px;
}
.focusable:focus {
  outline: none;
  border-color: var(--focus-ring);
  box-shadow: 0 0 20px var(--focus-glow);
}

/* --- Nav Bar --- */
.nav-bar {
  display: flex;
  gap: 8px;
  padding: 12px 20px;
  background: var(--bg-secondary);
  flex-shrink: 0;
}
.nav-item {
  flex: 1;
  padding: 14px 16px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 15px;
  font-weight: 500;
  text-align: center;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.nav-item:focus { background: var(--bg-card); }
.nav-item.primary {
  background: var(--accent-primary);
  color: var(--bg-primary);
}
.nav-item.primary:focus { background: #33ddff; }
.nav-item.danger {
  background: transparent;
  color: var(--danger);
  border: 2px solid var(--danger);
}
.nav-item.danger:focus {
  background: rgba(255, 85, 119, 0.12);
  box-shadow: 0 0 20px rgba(255, 85, 119, 0.3);
}

/* ==================== HOME SCREEN ==================== */
.home-content {
  align-items: stretch;
  justify-content: flex-start;
  gap: 14px;
}
.home-subtitle {
  font-size: 13px;
  color: var(--text-secondary);
  letter-spacing: 0.5px;
  text-transform: uppercase;
  text-align: center;
}
.duration-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}
.duration-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-radius: var(--radius-lg);
  padding: 14px 8px;
  min-height: 96px;
}
.duration-btn:focus {
  background: var(--bg-card);
}
.duration-num {
  font-size: 36px;
  font-weight: 700;
  color: var(--accent-primary);
  line-height: 1;
}
.duration-lbl {
  font-size: 13px;
  color: var(--text-secondary);
  letter-spacing: 0.5px;
}

/* ==================== SESSION SCREEN ==================== */
.session-stage {
  flex: 1;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

/* Ambient pulsing radial gradient */
.ambient {
  position: absolute;
  width: 560px;
  height: 560px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 212, 255, 0.18) 0%, rgba(0, 212, 255, 0.06) 40%, transparent 70%);
  transform: scale(1);
  will-change: transform, opacity;
  pointer-events: none;
}

/* Breathing circle — single element, transform-only animation */
.breath-circle {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  border: 2px solid var(--accent-primary);
  background: radial-gradient(circle, rgba(0, 212, 255, 0.22) 0%, rgba(0, 212, 255, 0.08) 60%, transparent 100%);
  box-shadow: 0 0 40px rgba(0, 212, 255, 0.25), inset 0 0 40px rgba(0, 212, 255, 0.15);
  transform: scale(0.5);
  will-change: transform;
}

/* Text overlay on top of the circle */
.session-overlay {
  position: absolute;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  pointer-events: none;
}
.phase-label {
  font-size: 20px;
  font-weight: 500;
  color: var(--accent-primary);
  letter-spacing: 2px;
  text-transform: uppercase;
  min-height: 24px;
}
.countdown {
  font-size: 42px;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
  letter-spacing: 1px;
}

/* Paused visual hint */
.session-stage.paused .breath-circle,
.session-stage.paused .ambient {
  opacity: 0.4;
}
.session-stage.paused .phase-label::after {
  content: ' \00B7 paused';
  color: var(--text-secondary);
  letter-spacing: 1px;
}

/* ==================== COMPLETE SCREEN ==================== */
.complete-stage {
  flex: 1;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}
.complete-circle {
  width: 260px;
  height: 260px;
  border-radius: 50%;
  border: 2px solid var(--accent-primary);
  background: radial-gradient(circle, rgba(0, 212, 255, 0.30) 0%, rgba(0, 212, 255, 0.10) 60%, transparent 100%);
  box-shadow: 0 0 60px rgba(0, 212, 255, 0.35), inset 0 0 50px rgba(0, 212, 255, 0.20);
  animation: complete-scale-in 1200ms cubic-bezier(0.2, 0.8, 0.2, 1) both;
}
@keyframes complete-scale-in {
  0%   { transform: scale(0.5); opacity: 0; }
  60%  { transform: scale(1.05); opacity: 1; }
  100% { transform: scale(1); opacity: 1; }
}
.complete-overlay {
  position: absolute;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  text-align: center;
}
.complete-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--accent-primary);
  letter-spacing: 1.5px;
}
.complete-sub {
  font-size: 14px;
  color: var(--text-secondary);
  letter-spacing: 0.5px;
}
.complete-stats {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 6px;
}

/* ==================== HISTORY SCREEN ==================== */
.list-container {
  display: flex;
  flex-direction: column;
  gap: 8px;
  overflow-y: auto;
  max-height: 440px;
}
.history-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  min-height: 56px;
}
.history-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-primary);
  flex-shrink: 0;
}
.history-main { flex: 1; min-width: 0; }
.history-date {
  font-size: 15px;
  font-weight: 500;
  color: var(--text-primary);
}
.history-time {
  font-size: 12px;
  color: var(--text-secondary);
  margin-top: 2px;
}
.history-dur {
  font-size: 18px;
  font-weight: 700;
  color: var(--accent-primary);
  flex-shrink: 0;
}
.history-dur-unit {
  font-size: 12px;
  color: var(--text-secondary);
  margin-left: 2px;
  font-weight: 400;
}
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 48px 24px;
  text-align: center;
  flex: 1;
}
.empty-icon {
  font-size: 48px;
  color: var(--accent-dim);
}
.empty-text {
  font-size: 15px;
  color: var(--text-secondary);
}

/* --- Utility --- */
.hidden { display: none !important; }