/* CSS Variables */
:root {
  --color-primary: #6c5ce7;
  --color-primary-hover: #5b4bc4;
  --color-bg: #f9fafb;
  --color-surface: #ffffff;
  --color-text: #1f2937;
  --color-text-muted: #6b7280;
  --color-border: #e5e7eb;

  --font-sans:
    'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

  --transition: 0.2s ease-in-out;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #111827;
    --color-surface: #1f2937;
    --color-text: #f9fafb;
    --color-text-muted: #9ca3af;
    --color-border: #374151;
    --color-primary: #818cf8;
    --color-primary-hover: #a5b4fc;
  }
}

/* Reset & Basics */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  margin-top: 0;
  margin-bottom: var(--spacing-md);
  font-weight: 700;
  line-height: 1.2;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--color-primary-hover);
}

ul,
ol {
  padding-left: var(--spacing-xl);
}

img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
}

/* Layout */
.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Header */
.site-header {
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing-md) 0;
  position: sticky;
  top: 0;
  z-index: 10;
  box-shadow: var(--shadow-sm);
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.site-title:hover {
  color: var(--color-primary);
}

.site-logo {
  width: 48px;
  height: 48px;
  border-radius: 8px;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  gap: var(--spacing-lg);
  align-items: center;
}

.nav-link {
  color: var(--color-text-muted);
  font-weight: 500;
}

.nav-link:hover {
  color: var(--color-primary);
}

.lang-switch {
  display: flex;
  gap: var(--spacing-sm);
  font-size: 0.875rem;
}

/* Main */
.site-main {
  padding: var(--spacing-2xl) 0;
  min-height: calc(100vh - 160px);
  /* rough footer/header height calc */
}

/* Post Grid */
.page-title {
  margin-bottom: var(--spacing-xl);
  font-size: 2.5rem;
  text-align: center;
}

.post-grid {
  display: grid;
  gap: var(--spacing-lg);
  list-style: none;
  padding: 0;
  margin: 0;
}

.post-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  transition:
    transform var(--transition),
    box-shadow var(--transition),
    border-color var(--transition);
  display: flex;
  flex-direction: column;
}

.post-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.post-card h2 {
  font-size: 1.5rem;
  margin-bottom: var(--spacing-xs);
}

.post-card h2 a {
  color: var(--color-text);
}

.post-card h2 a:hover {
  color: var(--color-primary);
}

.post-meta {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

.post-excerpt {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
  flex-grow: 1;
}

.read-more {
  display: inline-flex;
  align-items: center;
  font-weight: 600;
  color: var(--color-primary);
  font-size: 0.875rem;
}

.read-more::after {
  content: '→';
  margin-left: var(--spacing-xs);
  transition: transform var(--transition);
}

.post-card:hover .read-more::after {
  transform: translateX(4px);
}

/* Post Article */
.post-article {
  background: var(--color-surface);
  padding: var(--spacing-2xl);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
}

.post-header {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
}

.post-header h1 {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-sm);
}

.post-content h2 {
  margin-top: var(--spacing-2xl);
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--spacing-xs);
}

.post-content h3 {
  margin-top: var(--spacing-xl);
}

.post-content p {
  margin-bottom: var(--spacing-md);
  font-size: 1.125rem;
}

.post-content ul,
.post-content ol {
  font-size: 1.125rem;
  margin-bottom: var(--spacing-md);
}

.post-content pre {
  background: var(--color-bg);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  overflow-x: auto;
  border: 1px solid var(--color-border);
}

.post-content code {
  font-family: var(--font-mono);
  background: var(--color-bg);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
}

.post-content pre code {
  background: none;
  padding: 0;
}

.post-content blockquote {
  border-left: 4px solid var(--color-primary);
  margin: 0 0 var(--spacing-md) 0;
  padding-left: var(--spacing-md);
  color: var(--color-text-muted);
  font-style: italic;
}

.post-footer {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
  text-align: center;
}

.btn-back {
  display: inline-flex;
  align-items: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text);
  font-weight: 500;
  transition: all var(--transition);
}

.btn-back:hover {
  background: var(--color-border);
  color: var(--color-text);
}

/* Footer */
.site-footer {
  text-align: center;
  padding: var(--spacing-xl) 0;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  margin-top: auto;
}

.site-footer p {
  margin: 0;
  font-size: 0.875rem;
}

/* Utils */
.empty-state {
  text-align: center;
  padding: var(--spacing-2xl);
  color: var(--color-text-muted);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px dashed var(--color-border);
}

/* ── Book pages ──────────────────────────────────────────────────────────── */

/* Hub: /books/ */
.books-hub .page-title {
  text-align: center;
  margin-bottom: var(--spacing-sm);
}

.books-intro {
  text-align: center;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-2xl);
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--spacing-lg);
  list-style: none;
  padding: 0;
  margin: 0;
}

.book-card {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  text-decoration: none;
  color: var(--color-text);
  transition:
    transform var(--transition),
    box-shadow var(--transition),
    border-color var(--transition);
}

.book-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
  color: var(--color-text);
}

.book-cover img {
  width: 100%;
  aspect-ratio: 2 / 3;
  object-fit: cover;
  border-radius: 0;
  display: block;
}

.book-info {
  padding: var(--spacing-md);
}

.book-card-title {
  font-size: 1rem;
  margin-bottom: var(--spacing-xs);
  line-height: 1.3;
}

.book-card-author {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin: 0 0 var(--spacing-xs);
}

.book-card-lang {
  font-size: 0.75rem;
  color: var(--color-primary);
  font-weight: 600;
  margin: 0;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Individual book page: /book/<slug>/ */
.book-page-hero {
  display: flex;
  gap: var(--spacing-2xl);
  align-items: flex-start;
  margin-bottom: var(--spacing-2xl);
}

.book-page-cover {
  flex: 0 0 320px;
  position: sticky;
  top: calc(60px + var(--spacing-xl));
}

.book-page-cover img {
  width: 100%;
  aspect-ratio: 2 / 3;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  display: block;
}

.book-page-header {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.book-page-header h1 {
  font-size: 2rem;
  margin-bottom: var(--spacing-xs);
}

.book-author {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-xs);
}

.book-lang {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin: 0 0 0;
}

.book-page-meta {
  flex: 1;
  min-width: 0;
  padding-top: var(--spacing-xs);
}

.book-play-section {
  margin-bottom: var(--spacing-2xl);
}

.book-play-section h2 {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

.play-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.play-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.play-label {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}

.btn-play {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  min-width: 95px;
  /* Premium consistent columnar alignment */
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.875rem;
  white-space: nowrap;
  text-decoration: none;
  transition:
    background var(--transition),
    transform var(--transition),
    box-shadow var(--transition);
}

.btn-play:hover {
  background: var(--color-primary-hover);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-play:active {
  transform: translateY(0);
}

.book-page-footer {
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
}

/* Responsive adjustments for book details */
@media (max-width: 768px) {
  .book-page-hero {
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xl);
  }

  .book-page-cover {
    flex: none;
    position: static;
    max-width: 260px;
    width: 100%;
    margin: 0 auto;
  }

  .book-page-meta {
    width: 100%;
  }

  .book-play-section h2 {
    text-align: center;
  }

  .play-links {
    align-items: center;
  }

  .play-item {
    width: 100%;
    max-width: 320px;
    /* Centered block width */
    justify-content: flex-start;
    /* Consistent vertical column alignment */
  }
}

@media (max-width: 480px) {
  .site-nav {
    flex-direction: column;
    gap: var(--spacing-sm);
  }

  .nav-links {
    gap: var(--spacing-md);
  }

  .play-item {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-xs);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    box-shadow: var(--shadow-sm);
  }

  .btn-play {
    width: 100%;
    padding: var(--spacing-md);
    /* enhanced tap target on mobile */
    font-size: 0.9375rem;
  }

  .play-label {
    text-align: center;
    font-size: 0.8125rem;
    margin-top: var(--spacing-xs);
  }
}