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

/* Light mode (default) */
:root {
  --bg-primary: #f4f6fb;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-hover: rgba(255, 255, 255, 0.95);
  --border-card: rgba(60, 100, 200, 0.15);
  --accent: #3a6fd8;
  --accent-glow: rgba(58, 111, 216, 0.25);
  --accent-secondary: #00a884;
  --text-primary: #1c2333;
  --text-secondary: #5a6478;
  --text-muted: #8892a8;
  --danger: #e0333f;
  --success: #00a884;
  --radius: 16px;
  --radius-sm: 10px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);

  --card-shadow: 0 4px 24px rgba(30, 40, 80, 0.06);
  --surface-tint: rgba(0, 0, 0, 0.03);
  --surface-tint-hover: rgba(0, 0, 0, 0.02);
  --input-bg: rgba(0, 0, 0, 0.02);
  --btn-generate-end: #2c5bb8;
}

/* Dark mode override */
[data-theme="dark"] {
  --bg-primary: #0a0e1a;
  --bg-card: rgba(15, 20, 40, 0.85);
  --bg-card-hover: rgba(20, 28, 55, 0.9);
  --border-card: rgba(100, 140, 255, 0.12);
  --accent: #4f8cff;
  --accent-glow: rgba(79, 140, 255, 0.3);
  --accent-secondary: #00d4aa;
  --text-primary: #e8ecf4;
  --text-secondary: #8892a8;
  --text-muted: #5a6478;
  --danger: #ff5c6c;
  --success: #00d4aa;

  --card-shadow: none;
  --surface-tint: rgba(255, 255, 255, 0.02);
  --surface-tint-hover: rgba(255, 255, 255, 0.02);
  --input-bg: rgba(10, 14, 26, 0.5);
  --btn-generate-end: #3a6fd8;
}

body {
  font-family:
    "Inter",
    -apple-system,
    BlinkMacSystemFont,
    sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  overflow-x: hidden;
  transition: background var(--transition), color var(--transition);
}

/* Animated background gradient */
body::before {
  content: "";
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background:
    radial-gradient(
      ellipse at 30% 20%,
      var(--accent-glow) 0%,
      transparent 50%
    ),
    radial-gradient(
      ellipse at 70% 80%,
      rgba(0, 168, 132, 0.04) 0%,
      transparent 50%
    );
  opacity: 0.6;
  animation: bgShift 20s ease-in-out infinite alternate;
  z-index: -1;
}

@keyframes bgShift {
  0% {
    transform: translate(0, 0) rotate(0deg);
  }

  100% {
    transform: translate(-5%, 3%) rotate(3deg);
  }
}

.container {
  width: 100%;
  max-width: 580px;
}

/* Theme toggle button */
.theme-toggle {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border-card);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  backdrop-filter: blur(20px);
  transition: var(--transition);
  z-index: 10;
}

.theme-toggle:hover {
  background: var(--bg-card-hover);
  box-shadow: 0 4px 16px var(--accent-glow);
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 2.5rem;
}

.header-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  border-radius: 20px;
  background: linear-gradient(135deg, var(--accent), var(--accent-secondary));
  margin-bottom: 1.25rem;
  font-size: 1.75rem;
  box-shadow: 0 8px 32px var(--accent-glow);
  animation: iconPulse 3s ease-in-out infinite;
}

@keyframes iconPulse {
  0%,
  100% {
    box-shadow: 0 8px 32px var(--accent-glow);
  }

  50% {
    box-shadow: 0 8px 48px var(--accent-glow);
  }
}

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
  background: linear-gradient(135deg, var(--text-primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.5;
}

/* Card */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius);
  padding: 2rem;
  backdrop-filter: blur(20px);
  box-shadow: var(--card-shadow);
  transition: var(--transition);
}

/* Tabs */
.tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  background: var(--surface-tint);
  padding: 0.35rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-card);
}

.tab-btn {
  flex: 1;
  padding: 0.75rem 0.5rem;
  border: none;
  border-radius: calc(var(--radius-sm) - 4px);
  background: transparent;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
}

.tab-btn:hover {
  color: var(--text-primary);
  background: var(--surface-tint-hover);
}

.tab-btn.active {
  background: var(--accent-glow);
  color: var(--accent);
  box-shadow: inset 0 0 12px var(--accent-glow);
}

/* API Key Input */
.api-key-container {
  margin-bottom: 1.5rem;
}

.api-key-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.api-key-input {
  width: 100%;
  padding: 0.85rem 1rem;
  background: var(--input-bg);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  outline: none;
  transition: var(--transition);
}

.api-key-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 12px var(--accent-glow);
}

/* Dropzone */
.dropzone {
  border: 2px dashed var(--border-card);
  border-radius: var(--radius-sm);
  padding: 2.5rem 1.5rem;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
}

.dropzone:hover,
.dropzone.drag-over {
  border-color: var(--accent);
  background: var(--surface-tint);
}

.dropzone-icon {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  display: block;
}

.dropzone-text {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
}

.dropzone-text strong {
  color: var(--accent);
  font-weight: 600;
}

.file-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}

/* File selected state */
.file-info {
  display: none;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  background: var(--surface-tint);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  margin-top: 1.25rem;
}

.file-info.visible {
  display: flex;
}

.file-info-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

.file-info-name {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
}

.file-info-size {
  font-size: 0.75rem;
  color: var(--text-muted);
  flex-shrink: 0;
}

.file-remove {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 0.25rem;
  transition: var(--transition);
  flex-shrink: 0;
}

.file-remove:hover {
  color: var(--danger);
}

/* Submit button */
.btn-generate {
  width: 100%;
  padding: 0.95rem;
  margin-top: 1.5rem;
  border: none;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), var(--btn-generate-end));
  color: #fff;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.btn-generate:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 6px 24px var(--accent-glow);
}

.btn-generate:active:not(:disabled) {
  transform: translateY(0);
}

.btn-generate:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Progress */
.progress-section {
  display: none;
  margin-top: 1.5rem;
}

.progress-section.visible {
  display: block;
}

.progress-bar-track {
  width: 100%;
  height: 6px;
  background: var(--accent-glow);
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-secondary));
  border-radius: 3px;
  transition: width 0.5s ease;
}

.progress-bar-fill.indeterminate {
  width: 30%;
  animation: indeterminate 1.5s ease-in-out infinite;
}

@keyframes indeterminate {
  0% {
    transform: translateX(-100%);
  }

  100% {
    transform: translateX(400%);
  }
}

.progress-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.spinner {
  width: 16px;
  height: 16px;
  border: 2px solid var(--accent-glow);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Result */
.result-section {
  display: none;
  margin-top: 1.5rem;
}

.result-section.visible {
  display: block;
  animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.result-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.85rem;
  background: rgba(0, 168, 132, 0.08);
  border: 1px solid rgba(0, 168, 132, 0.2);
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--success);
  margin-bottom: 1rem;
}

.audio-player {
  width: 100%;
  margin: 1rem 0;
  border-radius: var(--radius-sm);
  outline: none;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  width: 100%;
  padding: 0.85rem;
  border: 1px solid rgba(0, 168, 132, 0.3);
  border-radius: var(--radius-sm);
  background: rgba(0, 168, 132, 0.06);
  color: var(--success);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: var(--transition);
}

.btn-download:hover {
  background: rgba(0, 168, 132, 0.12);
  box-shadow: 0 4px 16px rgba(0, 168, 132, 0.12);
}

/* Error */
.error-message {
  display: none;
  margin-top: 1rem;
  padding: 0.85rem 1rem;
  background: rgba(224, 51, 63, 0.06);
  border: 1px solid rgba(224, 51, 63, 0.2);
  border-radius: var(--radius-sm);
  color: var(--danger);
  font-size: 0.85rem;
  line-height: 1.5;
}

.error-message.visible {
  display: block;
  animation: fadeIn 0.3s ease;
}

/* Footer */
.footer {
  margin-top: 2rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.75rem;
}

/* Responsive */
@media (max-width: 640px) {
  body {
    padding: 1rem;
  }

  .card {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.5rem;
  }

  .theme-toggle {
    top: 1rem;
    right: 1rem;
  }
}

/* Chapter analysis loading indicator (spec 008) */
.chapter-select-hint {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.chapter-select-hint.is-loading {
  opacity: 1;
}

.chapter-spinner {
  display: inline-block;
  width: 0.9rem;
  height: 0.9rem;
  border: 2px solid rgba(128, 128, 128, 0.35);
  border-top-color: var(--danger, #9e1b1b);
  border-radius: 50%;
  animation: chapter-spin 0.7s linear infinite;
  flex-shrink: 0;
}

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

.chapter-select-container select:disabled.is-analyzing {
  cursor: progress;
  opacity: 0.8;
}