/* ==========================================================================
   stephango-style Minimal Theme
   ========================================================================== */

:root {
  /* Colors - Light Mode */
  --color-bg: #faf5ed;
  --color-bg-elevated: #fffdf9;
  --color-text: #1a1a1a;
  --color-text-secondary: #666;
  --color-text-tertiary: #999;
  --color-link: #1a1a1a;
  --color-link-hover: #555;
  --color-border: #e6e1d8;
  --color-accent: #7c3aed;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Layout */
  --max-width: 640px;
}

/* Dark Mode */
[data-theme="dark"] {
  --color-bg: #0f0f0f;
  --color-bg-elevated: #1a1a1a;
  --color-text: #e5e5e5;
  --color-text-secondary: #a0a0a0;
  --color-text-tertiary: #949494;
  --color-link: #e5e5e5;
  --color-link-hover: #c0c0c0;
  --color-border: #2a2a2a;
  --color-accent: #a78bfa;
}

/* ==========================================================================
   Base Styles
   ========================================================================== */

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  transition: background-color 0.3s ease, color 0.3s ease;
  font-feature-settings: 'cv01' on, 'tnum' on;
}

body.menu-open {
  overflow: hidden;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-lg);
}

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.15s ease;
}

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

/* ==========================================================================
   Header & Navigation
   ========================================================================== */

.header {
  margin-bottom: var(--spacing-3xl);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--spacing-md);
}

.logo {
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--color-text);
  white-space: nowrap;
}

.logo:hover {
  color: var(--color-text);
}

.nav-links {
  display: flex;
  gap: var(--spacing-lg);
  order: 2;
}

.nav-link {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  transition: color 0.15s ease;
  white-space: nowrap;
}

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

.theme-toggle {
  order: 3;
}

/* ==========================================================================
   Pill Theme Toggle
   ========================================================================== */

/* Disable transitions on page load */
.theme-toggle.no-transition .toggle-track,
.theme-toggle.no-transition .toggle-knob {
  transition: none !important;
}

.theme-toggle {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  display: flex;
  align-items: center;
}

.toggle-track {
  width: 44px;
  height: 24px;
  background: var(--color-border);
  border-radius: 12px;
  position: relative;
  transition: background-color 0.3s ease;
}

.toggle-knob {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 18px;
  height: 18px;
  background: var(--color-text-tertiary);
  border-radius: 50%;
  transition: transform 0.3s ease, background-color 0.3s ease;
}

/* Dark mode toggle state */
.theme-toggle.dark .toggle-track {
  background: var(--color-accent);
}

.theme-toggle.dark .toggle-knob {
  transform: translateX(20px);
  background: #fff;
}

/* Respect user's motion preferences */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ==========================================================================
   Mobile: Two-row Layout
   ========================================================================== */

@media (max-width: 640px) {
  .nav {
    gap: var(--spacing-sm) var(--spacing-md);
  }
  
  .logo {
    order: 1;
    font-size: 1rem;
  }
  
  .theme-toggle {
    order: 2;
  }
  
  .nav-links {
    order: 3;
    width: 100%;
    gap: var(--spacing-md);
  }
  
  .nav-link {
    font-size: 0.9rem;
  }
  
  .toggle-track {
    width: 36px;
    height: 20px;
  }
  
  .toggle-knob {
    width: 14px;
    height: 14px;
  }
  
  .theme-toggle.dark .toggle-knob {
    transform: translateX(16px);
  }
}

/* ==========================================================================
   Home Page
   ========================================================================== */

.home {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3xl);
}

/* Latest Post Feature */
.latest {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.latest-label {
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.latest-post {
  display: block;
  padding: var(--spacing-lg);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  transition: border-color 0.15s ease, background-color 0.3s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

.latest-post:hover {
  border-color: var(--color-text-secondary);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  transform: translateY(-2px);
}

[data-theme="dark"] .latest-post:hover {
  box-shadow: 0 4px 20px rgba(139, 92, 246, 0.15);
}

.latest-title {
  margin: 0 0 var(--spacing-sm);
  font-size: 1.25rem;
  font-weight: 500;
  line-height: 1.3;
}

.latest-meta {
  margin: 0 0 var(--spacing-md);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.latest-excerpt {
  margin: 0 0 var(--spacing-md);
  font-family: var(--font-serif);
  font-size: 1rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.keep-reading {
  font-size: 0.9rem;
  color: var(--color-accent);
  display: inline-block;
}

.keep-reading::after {
  content: '';
  display: inline-block;
  width: 0;
  transition: width 0.2s ease;
}

.latest-post:hover .keep-reading::after {
  width: 4px;
}

/* Topics Section */
.topics {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.section-title {
  margin: 0;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.section-title a {
  color: inherit;
}

.topic-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

.topic,
.tag {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  padding: var(--spacing-xs) var(--spacing-sm);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  transition: all 0.15s ease;
  text-decoration: none;
  background: var(--color-bg);
}

.topic:hover,
.tag:hover {
  color: var(--color-text);
  border-color: var(--color-text-secondary);
  background: var(--color-bg-elevated);
}

/* Year-Grouped Writing List */
.writing {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.year-group {
  margin-bottom: var(--spacing-md);
}

.essay-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
}

.essay-item {
  border-top: 1px solid var(--color-border);
}

.essay-item:last-child {
  border-bottom: 1px solid var(--color-border);
}

.essay-item a {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: var(--spacing-md);
  padding: var(--spacing-md) 0;
  color: var(--color-text);
  align-items: baseline;
  text-decoration: none;
}

.essay-item a:hover {
  color: var(--color-text-secondary);
}

.essay-date {
  flex-shrink: 0;
  width: 70px;
  font-size: 0.9rem;
  color: var(--color-text-tertiary);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.essay-title {
  font-size: 0.95rem;
}

/* ==========================================================================
   Single Post
   ========================================================================== */

.post {
  max-width: var(--max-width);
}

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

.post-title {
  margin: 0 0 var(--spacing-sm);
  font-size: 2rem;
  font-weight: 600;
  line-height: 1.2;
}

.post-meta {
  margin: 0;
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

.post-meta.visible-meta {
  margin-top: var(--spacing-sm);
  display: block;
}

.post-content {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  line-height: 1.65;
  font-optical-sizing: auto;
}

.post-content h2 {
  margin: var(--spacing-2xl) 0 var(--spacing-md);
  font-family: var(--font-sans);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.post-content h3 {
  margin: var(--spacing-xl) 0 var(--spacing-md);
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.post-content p {
  margin: 0 0 var(--spacing-lg);
}

.post-content a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.post-content a:hover {
  color: var(--color-link-hover);
}

.post-content blockquote {
  margin: var(--spacing-lg) 0;
  padding: var(--spacing-md) var(--spacing-lg);
  border-left: 3px solid var(--color-accent);
  background: var(--color-bg-elevated);
  border-radius: 0 6px 6px 0;
  font-style: italic;
  color: var(--color-text-secondary);
}

.post-content blockquote p:last-child {
  margin-bottom: 0;
}

.post-content ul, .post-content ol {
  margin: 0 0 var(--spacing-lg);
  padding-left: var(--spacing-lg);
}

.post-content li {
  margin-bottom: var(--spacing-sm);
}

.post-content code {
  font-family: 'SF Mono', 'Menlo', monospace;
  font-size: 0.9em;
  padding: 0.15em 0.4em;
  background: var(--color-border);
  border-radius: 3px;
}

.post-content pre {
  margin: var(--spacing-lg) 0;
  padding: var(--spacing-md);
  background: #1a1a1a;
  border-radius: 6px;
  overflow-x: auto;
}

.post-content pre code {
  background: none;
  padding: 0;
  color: #e5e5e5;
}

.post-content img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  display: block;
  margin: 0 auto;
}

/* Figure and Caption Styling */
.post-content figure,
.post-content .figure {
  margin: var(--spacing-xl) 0;
  text-align: center;
}

.post-content figcaption,
.post-content .figure-caption {
  margin-top: var(--spacing-sm);
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
  text-align: center;
  font-family: var(--font-sans); /* Use sans-serif for captions */
}

/* Math (KaTeX) Overflow Handling */
.post-content .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: var(--spacing-sm) 0;
}

.post-content hr {
  margin: var(--spacing-2xl) 0;
  border: none;
  border-top: 1px solid var(--color-border);
}

/* Post Footer */
.post-footer {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

.tag {
  font-size: 0.85rem;
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--color-border);
  border-radius: 4px;
  color: var(--color-text-secondary);
  transition: background-color 0.15s ease, color 0.15s ease;
}

.tag:hover {
  background: var(--color-accent);
  color: #fff;
}

/* ==========================================================================
   Post Navigation (Next/Previous)
   ========================================================================== */

.post-nav {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  gap: var(--spacing-lg);
}

.post-nav-prev,
.post-nav-next {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  max-width: 45%;
}

.post-nav-next {
  text-align: right;
  margin-left: auto;
}

.post-nav-label {
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
}

.post-nav-title {
  font-size: 0.95rem;
  color: var(--color-text);
  transition: color 0.15s ease;
}

.post-nav-prev:hover .post-nav-title,
.post-nav-next:hover .post-nav-title {
  color: var(--color-accent);
}

/* Back to Top Link */
.back-to-top-wrapper {
  margin-top: var(--spacing-xl);
  text-align: center;
}

.back-to-top {
  font-size: 0.9rem;
  color: var(--color-text-tertiary);
  transition: color 0.15s ease;
}

.back-to-top:hover {
  color: var(--color-accent);
}

/* Reading Progress Bar */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), #a78bfa);
  z-index: 9999;
  transition: width 0.1s ease-out;
}

/* ==========================================================================
   Old Article Alert
   ========================================================================== */

.alert-old {
  background-color: #fef3c7; /* yellow-100 */
  border: 1px solid #f59e0b; /* amber-500 */
  color: #92400e; /* amber-800 */
  padding: var(--spacing-md);
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  border-radius: 6px;
  font-size: 0.95rem;
  line-height: 1.5;
}

[data-theme="dark"] .alert-old {
  background-color: #451a03; /* amber-950/900 */
  border-color: #d97706; /* amber-600 */
  color: #fcd34d; /* amber-300 */
}

/* ==========================================================================
   Home Greeting
   ========================================================================== */

.greeting {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  line-height: 1.6;
  color: var(--color-text-secondary);
  margin: 0;
}

/* ==========================================================================
   List Page
   ========================================================================== */

.list-page {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xl);
}

.list-title {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 600;
}

.list-content {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  margin-top: var(--spacing-3xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.newsletter,
.email-cta {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  padding: var(--spacing-lg);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: 8px;
}

@media (min-width: 640px) {
  .email-cta {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    text-align: left;
  }
}

.email-cta p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

.email-button {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-lg);
  background: var(--color-accent);
  color: #fff;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: 500;
  white-space: nowrap;
  transition: background-color 0.15s ease, transform 0.15s ease;
  align-self: flex-start;
}

@media (min-width: 640px) {
  .email-button {
    align-self: center;
  }
}

.email-button:hover {
  background: #6d28d9;
  color: #fff;
  transform: translateY(-1px);
}

[data-theme="dark"] .email-button:hover {
  background: #c4b5fd;
  color: #1a1a1a;
}

.footer-links {
  display: flex;
  gap: var(--spacing-md);
}

.footer-links a {
  font-size: 0.9rem;
  color: var(--color-text-tertiary);
}

.footer-links a:hover {
  color: var(--color-text);
}

.copyright {
  margin: 0;
  font-size: 0.85rem;
  color: var(--color-text-tertiary);
}

/* ==========================================================================
   404 Error Page
   ========================================================================== */

.error-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  min-height: 50vh;
}

.error-code {
  font-size: 8rem;
  font-weight: 700;
  margin: 0;
  background: linear-gradient(135deg, var(--color-accent) 0%, #a78bfa 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
}

.error-message {
  font-size: 1.5rem;
  margin: var(--spacing-md) 0;
  color: var(--color-text);
}

.error-suggestion {
  color: var(--color-text-secondary);
  margin: 0 0 var(--spacing-xl);
}

.error-actions {
  display: flex;
  gap: var(--spacing-lg);
}

.error-link {
  padding: var(--spacing-sm) var(--spacing-lg);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  color: var(--color-text);
  transition: all 0.15s ease;
}

.error-link:hover {
  border-color: var(--color-accent);
  background: var(--color-bg-elevated);
}

/* ==========================================================================
   Responsive - Small Screens
   ========================================================================== */

@media (max-width: 640px) {
  .container {
    padding: var(--spacing-lg) var(--spacing-md);
  }
  
  .post-title {
    font-size: 1.6rem;
  }
  
  .essay-item a {
    flex-direction: column;
    gap: 0;
  }
  
  .essay-date {
    width: auto;
    font-size: 0.8rem;
  }
}

/* ==========================================================================
   Card Component
   ========================================================================== */

.card {
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: var(--spacing-lg);
  margin: var(--spacing-lg) 0;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

[data-theme="dark"] .card {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.card-body {
  padding: 0;
}

.card-title {
  font-family: var(--font-sans);
  font-size: 1.15rem;
  font-weight: 600;
  margin: 0 0 var(--spacing-md);
  color: var(--color-text);
}

.card-text {
  font-family: var(--font-serif);
  line-height: 1.7;
  color: var(--color-text);
}

.card-text p {
  margin-bottom: var(--spacing-md);
}

.card-text p:last-child {
  margin-bottom: 0;
}

.card-text a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* ==========================================================================
   Alert/Callout Blocks (GitHub-style)
   Usage: > [!UPDATE], > [!NOTE], > [!TIP], > [!WARNING]
   ========================================================================== */

.alert,
.callout,
.post-content blockquote:has(p:first-child strong:first-child) {
  position: relative;
}

/* Base alert styling - also style blockquotes with bold first word as alerts */
.alert,
.update-block {
  background: rgba(139, 92, 246, 0.08);
  border: 1px solid rgba(139, 92, 246, 0.2);
  border-left: 4px solid var(--color-accent);
  border-radius: 0 8px 8px 0;
  padding: var(--spacing-md) var(--spacing-lg);
  margin: var(--spacing-lg) 0;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  line-height: 1.6;
}

.alert::before,
.update-block::before {
  content: "Update";
  display: block;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--color-accent);
  margin-bottom: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

[data-theme="dark"] .alert,
[data-theme="dark"] .update-block {
  background: rgba(139, 92, 246, 0.12);
  border-color: rgba(139, 92, 246, 0.3);
}

.alert ul,
.update-block ul {
  margin: 0;
  padding-left: var(--spacing-lg);
}

.alert li,
.update-block li {
  margin-bottom: var(--spacing-xs);
}

.alert li:last-child,
.update-block li:last-child {
  margin-bottom: 0;
}

.alert a,
.update-block a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}