/**
 * CodePhysics - Dark Mode First Design
 * Typography-first, reading experience focused
 */

/* =============================================================================
 * SELF-HOSTED FONTS
 * Inter Variable (body) and JetBrains Mono (code)
 * Subset to Latin characters for optimal loading
 * ============================================================================= */

@font-face {
  font-family: 'Inter';
  font-style: normal;
  font-weight: 100 900;
  font-display: swap;
  src: url('/fonts/inter-variable.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: 'JetBrains Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url('/fonts/jetbrains-mono-regular.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
  font-feature-settings: 'liga' on, 'calt' on;
}

@font-face {
  font-family: 'JetBrains Mono';
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url('/fonts/jetbrains-mono-medium.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
  font-feature-settings: 'liga' on, 'calt' on;
}

/* CSS Custom Properties */
:root {
  /* Dark mode colors (default) - WCAG AA compliant
   * Text primary #e8e8e8 on bg #0f0f0f = 12.5:1 contrast
   * Text secondary #a0a0a0 on bg #0f0f0f = 7:1 contrast
   * Accent #3b82f6 on bg #0f0f0f = 5.2:1 contrast (AA pass)
   */
  --bg-primary: #0f0f0f;
  --bg-secondary: #1a1a1a;
  --bg-tertiary: #252525;
  --text-primary: #e8e8e8;
  --text-secondary: #a0a0a0;
  --text-muted: #707070;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --border: #2a2a2a;
  --code-bg: #1a1a1a;
  --code-border: #2a2a2a;

  /* Typography - Self-hosted fonts with system fallbacks */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Layout - 680px optimal for 65-75 characters per line */
  --max-width: 680px;
  --container-max-width: 1280px;
  --header-height: 64px;

  /* =============================================================================
   * FLUID TYPOGRAPHY (CPHY-9)
   * CSS clamp() for smooth scaling between 320px and 1440px viewports
   * Formula: clamp(min, preferred, max) where preferred uses vw
   * ============================================================================= */
  --font-size-body: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --font-size-h1: clamp(2rem, 1.75rem + 1.25vw, 2.5rem);
  --font-size-h2: clamp(1.5rem, 1.35rem + 0.75vw, 2rem);
  --font-size-h3: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);
  --font-size-small: clamp(0.875rem, 0.85rem + 0.125vw, 0.9375rem);

  /* Touch target minimum (44x44px for accessibility) */
  --touch-target-min: 44px;
}

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

* {
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--font-size-body);
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  height: var(--header-height);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

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

.nav-links {
  display: flex;
  gap: var(--space-lg);
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color 0.2s ease;
}

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

/* Main Content */
.main-content {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: var(--space-3xl) 0;
}

.hero h1 {
  font-size: var(--font-size-h1);
  font-weight: 700;
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.hero-tagline {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* Article List */
.latest-articles h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--space-xl);
  color: var(--text-primary);
}

.article-list {
  list-style: none;
}

.article-item {
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--border);
}

.article-item:last-child {
  border-bottom: none;
}

.article-item a {
  text-decoration: none;
  display: block;
}

.article-item h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
  transition: color 0.2s ease;
  display: block;
}

.article-item a:hover h3 {
  color: var(--accent);
}

.article-excerpt {
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
  font-size: 1rem;
  display: block;
  line-height: 1.6;
}

.article-item time {
  font-size: 0.875rem;
  color: var(--text-muted);
  display: block;
}

.no-articles {
  color: var(--text-secondary);
  font-style: italic;
}

.view-all {
  margin-top: var(--space-lg);
}

.view-all a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.view-all a:hover {
  text-decoration: underline;
}

/* Article Page */
.article-header {
  margin-bottom: var(--space-2xl);
}

.article-title {
  font-size: var(--font-size-h1);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  color: var(--text-secondary);
  font-size: 0.9375rem;
}

.article-tags {
  margin-top: var(--space-md);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.tag {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: var(--space-xs) var(--space-sm);
  border-radius: 4px;
  font-size: 0.8125rem;
}

/* Article Content / Prose */
/* Fluid type scale: H1 2-2.5rem, H2 1.5-2rem, H3 1.25-1.5rem, Body 1-1.125rem */
.prose h2 {
  font-size: var(--font-size-h2);
  font-weight: 600;
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
}

.prose h3 {
  font-size: var(--font-size-h3);
  font-weight: 600;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
}

.prose p {
  margin-bottom: var(--space-lg);
}

.prose a {
  color: var(--accent);
  text-decoration: none;
}

.prose a:hover {
  text-decoration: underline;
}

.prose ul, .prose ol {
  margin-bottom: var(--space-lg);
  padding-left: var(--space-xl);
}

.prose li {
  margin-bottom: var(--space-sm);
}

.prose blockquote {
  border-left: 3px solid var(--accent);
  padding-left: var(--space-lg);
  margin: var(--space-lg) 0;
  color: var(--text-secondary);
  font-style: italic;
}

.prose code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--code-bg);
  padding: 0.1em 0.3em;
  border-radius: 3px;
}

.prose pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 6px;
  padding: var(--space-lg);
  overflow-x: auto;
  margin-bottom: var(--space-lg);
}

.prose pre code {
  background: none;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.6;
}

.prose img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  margin: var(--space-lg) 0;
}

/* Wide images - break out of article container on desktop */
.prose .wide-image {
  margin: var(--space-xl) 0;
}

.prose .wide-image img {
  width: 100%;
  max-width: 100%;
  margin: 0;
}

.prose .wide-image figcaption {
  font-size: var(--font-size-small);
  color: var(--text-secondary);
  font-style: italic;
  margin-top: var(--space-sm);
  text-align: center;
}

@media (min-width: 768px) {
  .prose .wide-image {
    width: 100vw;
    max-width: 1000px;
    position: relative;
    left: 50%;
    transform: translateX(-50%);
  }
}

@media (min-width: 1200px) {
  .prose .wide-image {
    max-width: 1100px;
  }
}

.prose hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: var(--space-2xl) 0;
}

/* Article Footer */
.article-footer {
  margin-top: var(--space-2xl);
}

.article-footer a {
  color: var(--accent);
  text-decoration: none;
}

.article-footer a:hover {
  text-decoration: underline;
}

/* Site Footer */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: var(--space-xl) 0;
  margin-top: auto;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-container p {
  margin-bottom: var(--space-sm);
}

.footer-container a {
  color: var(--text-secondary);
  text-decoration: none;
}

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

/* =============================================================================
 * RESPONSIVE DESIGN (CPHY-9)
 * Mobile-first approach with min-width media queries
 * Breakpoints: 640px (mobile), 768px (tablet), 1024px (desktop)
 * Touch targets: minimum 44x44px for accessibility
 * ============================================================================= */

/* Touch target sizing for interactive elements */
.nav-links a,
.view-all a,
.footer-container a {
  min-height: var(--touch-target-min);
  display: inline-flex;
  align-items: center;
}

/* Article items need block layout with adequate touch target */
.article-item a {
  display: block;
  padding: var(--space-sm) 0;
}

/* Base styles (mobile-first, min 320px) */
/* Fluid typography handles scaling via clamp() */

/* Small screens (max-width: 639px) */
@media (max-width: 639px) {
  :root {
    --header-height: 56px;
  }

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

  .main-content {
    padding: var(--space-xl) var(--space-md);
  }

  .hero {
    padding: var(--space-2xl) 0;
  }
}

/* Tablet and up (min-width: 768px) */
@media (min-width: 768px) {
  .nav-container {
    max-width: var(--container-max-width);
  }

  .main-content {
    padding: var(--space-2xl) var(--space-xl);
  }
}

/* Desktop (min-width: 1024px) */
@media (min-width: 1024px) {
  .hero {
    padding: var(--space-3xl) 0;
  }

  .main-content {
    padding: var(--space-3xl) var(--space-lg);
  }
}