/* ============================================
   SLIDES — Layout, Navigation, Progress Bar
   ============================================ */

/* --- Slide layout --- */
/* Slides use opacity-only transition to avoid conflicting with scrollIntoView smooth scroll.
   The scroll handles movement; CSS handles visibility. */
.slide {
  height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 52px 24px 72px;
  position: relative;
  opacity: 0;
  transition: opacity 0.5s cubic-bezier(0.22, 1, 0.36, 1);
  overflow: hidden;
}

.slide.active {
  opacity: 1;
}

.slide-content {
  max-width: 960px;
  width: 100%;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 40px 48px;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

/* --- Slide number --- */
.slide-number {
  position: absolute;
  bottom: 20px;
  right: 24px;
  font-family: 'Rubik', sans-serif;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* --- Subtitle under H1 --- */
.subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  margin-top: 0.5rem;
}

/* --- Speaker line --- */
.speaker {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 1.5rem;
}

/* --- Block marker (above H2 titles) --- */
.block-label {
  font-family: 'Rubik', sans-serif;
  font-weight: 500;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

/* --- Section divider (bridge slides) --- */
.slide--bridge .slide-content {
  background: linear-gradient(160deg, var(--bg-surface), var(--bg-surface-2));
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.slide--bridge h2 {
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  max-width: 700px;
  margin: 0 auto;
}

.slide--bridge .bridge-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

/* --- Target slide (goal) --- */
.slide--target .target-card {
  background: var(--bg-surface);
  border: 2px solid var(--accent-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  text-align: center;
  max-width: 700px;
  margin: 0 auto;
}

.slide--target .target-icon {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

/* --- Navigation --- */
.navigation {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 12px;
  z-index: 1000;
}

.nav-btn {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  color: var(--text-primary);
  border: 1px solid var(--border);
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-family: 'Rubik', sans-serif;
  font-size: 0.875rem;
  font-weight: 500;
  transition: background var(--transition-fast), border-color var(--transition-fast);
}

.nav-btn:hover {
  background: var(--accent-light);
  border-color: var(--accent-border);
}

.nav-btn:disabled {
  background: var(--bg-surface-2);
  color: var(--text-muted);
  border-color: var(--border-light);
  cursor: not-allowed;
}

/* --- Progress bar (top) --- */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1001;
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-bottom: 1px solid var(--border-light);
  padding: 8px 24px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.progress-bar__label {
  font-family: 'Rubik', sans-serif;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
}

.progress-bar__track {
  flex: 1;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  background: var(--accent);
  border-radius: 2px;
  transition: width var(--transition-normal);
  width: 0%;
}

.progress-bar__counter {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  color: var(--text-muted);
  white-space: nowrap;
}

/* --- Loading state --- */
.loading {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  color: var(--text-muted);
  font-size: 1rem;
}

.loading::after {
  content: '';
  width: 24px;
  height: 24px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  margin-left: 12px;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .slide {
    padding: 46px 12px 66px;
  }

  .slide-content {
    padding: 24px 20px;
  }

  .navigation {
    width: 100%;
    justify-content: center;
    padding: 0 16px;
    gap: 8px;
  }

  .nav-btn {
    padding: 8px 16px;
    font-size: 0.8rem;
    flex-grow: 1;
    max-width: 140px;
    text-align: center;
  }

  .progress-bar {
    padding: 6px 16px;
  }

  .progress-bar__label {
    font-size: 0.65rem;
  }
}

@media (max-width: 480px) {
  .slide {
    padding: 42px 8px 62px;
  }

  .slide-content {
    padding: 20px 16px;
  }
}