/* ============================================================
   RoboLog — Design System
   The pulse of robotics
   ============================================================ */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;600;700&family=Inter:wght@400;500&family=JetBrains+Mono&display=swap');

/* --- CSS Variables --- */
:root {
  --bg:            #0a0e1a;
  --surface:       #111827;
  --surface-hover: #1a2235;
  --accent:        #00d4ff;
  --accent2:       #7c3aed;
  --text-primary:  #f1f5f9;
  --text-secondary:#94a3b8;
  --border:        #1e293b;
  --success:       #10b981;

  --font-headline: 'Space Grotesk', sans-serif;
  --font-body:     'Inter', sans-serif;
  --font-mono:     'JetBrains Mono', monospace;

  --radius:        12px;
  --transition:    all 0.3s ease;
}

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  min-height: 100vh;
}

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

a:hover {
  color: #fff;
}

img {
  max-width: 100%;
  display: block;
}

/* --- Grid Background --- */
.hero-grid {
  background-image:
    linear-gradient(rgba(0,212,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,212,255,0.04) 1px, transparent 1px);
  background-size: 40px 40px;
}

/* ============================================================
   NAVBAR
   ============================================================ */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  background: rgba(10, 14, 26, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-logo {
  font-family: var(--font-headline);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

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

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
}

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

/* ============================================================
   HERO SECTION (Homepage)
   ============================================================ */
.hero {
  padding: 6rem 2rem 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,212,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,212,255,0.04) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
}

.hero-eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
  padding: 0.35rem 0.85rem;
  border: 1px solid rgba(0,212,255,0.3);
  border-radius: 999px;
  background: rgba(0,212,255,0.06);
}

.hero-title {
  font-family: var(--font-headline);
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #fff 30%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-tagline {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 480px;
  margin: 0 auto 0;
}

/* ============================================================
   FILTER BAR
   ============================================================ */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  justify-content: center;
  padding: 2rem 2rem 0;
}

.filter-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 500;
  padding: 0.45rem 1rem;
  border-radius: 999px;
  cursor: pointer;
  transition: var(--transition);
}

.filter-btn:hover,
.filter-btn.active {
  background: rgba(0,212,255,0.12);
  border-color: var(--accent);
  color: var(--accent);
}

/* ============================================================
   POST GRID
   ============================================================ */
.section-label {
  font-family: var(--font-headline);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

.posts-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 3rem 2rem 5rem;
}

.post-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

/* ============================================================
   POST CARD
   ============================================================ */
.post-card {
  background: rgba(255,255,255,0.03);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: var(--transition);
  cursor: pointer;
}

.post-card:hover {
  background: var(--surface-hover);
  border-color: rgba(0,212,255,0.25);
  box-shadow: 0 0 20px rgba(0,212,255,0.15);
  transform: translateY(-2px);
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.card-category {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  background: rgba(0,212,255,0.1);
  border: 1px solid rgba(0,212,255,0.2);
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
}

.card-date {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.card-title {
  font-family: var(--font-headline);
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.card-summary {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  margin-top: auto;
  padding-top: 0.5rem;
}

.card-link:hover {
  gap: 0.6rem;
  color: #fff;
}

/* ============================================================
   POST PAGE — HEADER
   ============================================================ */
.post-header {
  max-width: 760px;
  margin: 0 auto;
  padding: 4rem 2rem 2.5rem;
}

.post-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.post-category {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  background: rgba(0,212,255,0.1);
  border: 1px solid rgba(0,212,255,0.25);
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
}

.post-date,
.post-read-time {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.post-date::before {
  content: '·';
  margin-right: 1rem;
  color: var(--border);
}

.post-read-time::before {
  content: '·';
  margin-right: 1rem;
  color: var(--border);
}

.post-title {
  font-family: var(--font-headline);
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.post-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  font-size: 0.8rem;
  color: var(--text-secondary);
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
}

/* ============================================================
   POST PAGE — CONTENT
   ============================================================ */
.post-content {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 2rem 5rem;
}

.post-content p {
  margin-bottom: 1.5rem;
  color: var(--text-primary);
}

.post-content p.lead {
  font-size: 1.1rem;
  color: var(--text-secondary);
  border-left: 3px solid var(--accent);
  padding-left: 1.25rem;
  margin-bottom: 2rem;
}

.post-content h2 {
  font-family: var(--font-headline);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.post-content h3 {
  font-family: var(--font-headline);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 2rem 0 0.75rem;
}

.post-content ul,
.post-content ol {
  padding-left: 1.5rem;
  margin-bottom: 1.5rem;
}

.post-content li {
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.post-content code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: rgba(0,212,255,0.08);
  border: 1px solid rgba(0,212,255,0.15);
  padding: 0.1em 0.4em;
  border-radius: 4px;
  color: var(--accent);
}

.post-content pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
}

.post-content pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.875rem;
  color: var(--text-primary);
}

/* --- Blockquote --- */
blockquote {
  margin: 2rem 0;
  padding: 1.5rem 2rem;
  background: rgba(124,58,237,0.08);
  border: 1px solid rgba(124,58,237,0.25);
  border-left: 4px solid var(--accent2);
  border-radius: var(--radius);
}

blockquote p {
  font-size: 1.1rem;
  font-style: italic;
  color: var(--text-primary);
  margin-bottom: 0.75rem !important;
}

blockquote cite {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-style: normal;
}

/* --- Video Embed --- */
.video-embed {
  margin: 2rem 0;
}

.video-wrapper {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: #000;
}

.video-wrapper iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border-radius: var(--radius);
}

.video-caption {
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-align: center;
  margin-top: 0.75rem !important;
  font-style: italic;
}

/* --- Key Takeaways --- */
.takeaways {
  background: rgba(16,185,129,0.06);
  border: 1px solid rgba(16,185,129,0.2);
  border-radius: var(--radius);
  padding: 1.5rem 2rem;
  margin: 2.5rem 0;
}

.takeaways h3 {
  font-family: var(--font-headline);
  font-size: 1rem;
  font-weight: 700;
  color: var(--success);
  margin-bottom: 1rem !important;
  margin-top: 0 !important;
}

.takeaways ul {
  margin-bottom: 0;
}

.takeaways li {
  color: var(--text-primary);
  font-size: 0.95rem;
}

/* --- Source Link --- */
.source-link {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.5rem;
  margin-top: 2.5rem;
  font-size: 0.9rem;
}

.source-link p {
  margin-bottom: 0 !important;
  color: var(--text-secondary);
}

.source-link a {
  color: var(--accent);
  font-weight: 500;
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  border-top: 1px solid var(--border);
  padding: 2.5rem 2rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

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

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

/* ============================================================
   DIVIDER
   ============================================================ */
.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
  margin: 0 2rem;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 640px) {
  .navbar {
    padding: 1rem;
  }

  .nav-links {
    gap: 1.25rem;
  }

  .hero {
    padding: 4rem 1.25rem 3rem;
  }

  .posts-section {
    padding: 2rem 1.25rem 4rem;
  }

  .post-grid {
    grid-template-columns: 1fr;
  }

  .post-header,
  .post-content {
    padding-left: 1.25rem;
    padding-right: 1.25rem;
  }

  blockquote {
    padding: 1rem 1.25rem;
  }
}