/* ============================================================
   Dan's Blog — Design System (Vanilla CSS)
   ============================================================ */

/* ---------- Google Fonts ---------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Fira+Code:wght@400;500&display=swap');

/* ---------- CSS Variables ---------- */
:root {
  /* Colors */
  --color-bg:         #0f1117;
  --color-surface:    #1a1d27;
  --color-surface-2:  #22263a;
  --color-border:     #2e3350;
  --color-primary:    #6c63ff;
  --color-primary-h:  #8b85ff;
  --color-accent:     #00d4aa;
  --color-text:       #e2e8f0;
  --color-muted:      #8892a4;
  --color-heading:    #ffffff;

  /* Typography */
  --font-sans: 'Inter', system-ui, sans-serif;
  --font-mono: 'Fira Code', monospace;
  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;
  --text-5xl:  3rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-24: 6rem;

  /* Layout */
  --max-width: 1100px;
  --radius-sm: 6px;
  --radius:    12px;
  --radius-lg: 20px;

  /* Transitions */
  --transition: 0.2s ease;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  font-size: var(--text-base);
}
img { max-width: 100%; display: block; }
a { color: var(--color-primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-primary-h); }
ul { list-style: none; }

/* ---------- Layout ---------- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}
section { padding: var(--space-24) 0; }

/* ---------- Navbar ---------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.navbar-brand {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-heading);
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.navbar-brand:hover { opacity: 0.9; }
.navbar-links { display: flex; align-items: center; gap: var(--space-8); }
.navbar-links a {
  color: var(--color-muted);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color var(--transition);
}
.navbar-links a:hover, .navbar-links a.active { color: var(--color-text); }
.navbar-lang {
  display: flex;
  gap: var(--space-2);
}
.lang-btn {
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  font-weight: 600;
  border: 1px solid var(--color-border);
  color: var(--color-muted);
  cursor: pointer;
  background: transparent;
  transition: all var(--transition);
}
.lang-btn.active, .lang-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: var(--space-2);
}
.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ---------- Hero ---------- */
.hero {
  padding: var(--space-24) 0 var(--space-16);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(108,99,255,0.15) 0%, transparent 70%);
  pointer-events: none;
}
.hero .container {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: var(--space-12);
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 6px 14px;
  border-radius: 100px;
  border: 1px solid rgba(108,99,255,0.4);
  background: rgba(108,99,255,0.1);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-primary-h);
  margin-bottom: var(--space-6);
}
.hero-badge::before { content: '✦'; }
.hero h1 {
  font-size: var(--text-5xl);
  font-weight: 700;
  color: var(--color-heading);
  line-height: 1.15;
  margin-bottom: var(--space-4);
}
.hero h1 .gradient {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-subtitle {
  font-size: var(--text-lg);
  color: var(--color-muted);
  margin-bottom: var(--space-8);
  max-width: 480px;
}
.hero-actions { display: flex; gap: var(--space-4); flex-wrap: wrap; }
.hero-avatar {
  width: 220px;
  height: 220px;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid var(--color-border);
  box-shadow: 0 0 60px rgba(108,99,255,0.2);
  flex-shrink: 0;
}
.hero-avatar img { width: 100%; height: 100%; object-fit: cover; }
.hero-highlights {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-8);
}
.highlight-chip {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 6px 12px;
  border-radius: 100px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  font-size: var(--text-xs);
  color: var(--color-muted);
}
.highlight-chip::before { content: '◆'; color: var(--color-accent); font-size: 8px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 10px 22px;
  border-radius: var(--radius);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  text-decoration: none;
}
.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), #5a52e0);
  color: #fff;
  box-shadow: 0 4px 20px rgba(108,99,255,0.35);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(108,99,255,0.5);
  color: #fff;
}
.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
}
.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
}

/* ---------- Section Headings ---------- */
.section-header { text-align: center; margin-bottom: var(--space-12); }
.section-tag {
  display: inline-block;
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}
.section-title {
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--space-4);
}
.section-desc { color: var(--color-muted); max-width: 520px; margin: 0 auto; }

/* ---------- Tech Stack ---------- */
.tech-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-6);
}
.tech-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
  transition: all var(--transition);
}
.tech-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-3px);
  box-shadow: 0 8px 30px rgba(108,99,255,0.15);
}
.tech-card-icon { font-size: 1.75rem; margin-bottom: var(--space-3); }
.tech-card-name {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-heading);
  margin-bottom: var(--space-3);
}
.tech-tags { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.tech-tag {
  font-size: var(--text-xs);
  padding: 3px 10px;
  border-radius: 100px;
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  color: var(--color-muted);
}

/* ---------- Projects ---------- */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-6);
}
.project-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}
.project-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(108,99,255,0.18);
}
.project-card-img {
  height: 160px;
  overflow: hidden;
  background: var(--color-surface-2);
}
.project-card-img img { width: 100%; height: 100%; object-fit: cover; }
.project-card-body { padding: var(--space-6); flex: 1; display: flex; flex-direction: column; }
.project-title {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-heading);
  margin-bottom: var(--space-2);
}
.project-desc {
  font-size: var(--text-sm);
  color: var(--color-muted);
  margin-bottom: var(--space-4);
  flex: 1;
}
.project-tags { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-bottom: var(--space-4); }
.project-tag {
  font-size: var(--text-xs);
  padding: 2px 8px;
  border-radius: 100px;
  background: rgba(108,99,255,0.12);
  border: 1px solid rgba(108,99,255,0.3);
  color: var(--color-primary-h);
}
.project-links { display: flex; gap: var(--space-3); }
.project-link {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-muted);
  display: flex;
  align-items: center;
  gap: 4px;
  transition: color var(--transition);
}
.project-link:hover { color: var(--color-primary); }

/* ---------- Blog List ---------- */
.blog-list { display: flex; flex-direction: column; gap: var(--space-4); }
.blog-card {
  display: grid;
  grid-template-columns: 200px 1fr;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all var(--transition);
  position: relative;
}
.blog-card:hover {
  border-color: var(--color-primary);
  transform: translateX(4px);
  box-shadow: 0 4px 24px rgba(108,99,255,0.12);
}
.blog-card-img {
  height: 140px;
  overflow: hidden;
  background: var(--color-surface-2);
}
.blog-card-img img { width: 100%; height: 100%; object-fit: cover; }
.blog-card-body {
  padding: var(--space-4) var(--space-6);
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.blog-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: var(--text-xs);
  color: var(--color-muted);
  margin-bottom: var(--space-2);
}
.blog-card-title {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-heading);
  margin-bottom: var(--space-2);
  line-height: 1.4;
}
.blog-card-title a { color: inherit; }
.blog-card-title a::after {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  z-index: 1;
}
.blog-card-title a:hover { color: var(--color-primary); }
.blog-card-desc {
  font-size: var(--text-sm);
  color: var(--color-muted);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.blog-card-cats { display: flex; gap: var(--space-2); margin-top: var(--space-3); flex-wrap: wrap; }
.cat-badge {
  font-size: var(--text-xs);
  padding: 2px 8px;
  border-radius: 100px;
  background: rgba(0,212,170,0.1);
  border: 1px solid rgba(0,212,170,0.3);
  color: var(--color-accent);
  position: relative;
  z-index: 2;
}

/* ---------- Category Filter ---------- */
.category-filter {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-8);
}
.filter-btn {
  padding: 6px 16px;
  border-radius: 100px;
  font-size: var(--text-sm);
  font-weight: 500;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-muted);
  cursor: pointer;
  transition: all var(--transition);
}
.filter-btn.active, .filter-btn:hover {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

/* ---------- Article Page ---------- */
.article-header {
  padding: var(--space-16) 0 var(--space-8);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-12);
}
.article-cats { display: flex; gap: var(--space-2); margin-bottom: var(--space-4); }
.article-title {
  font-size: var(--text-4xl);
  font-weight: 700;
  color: var(--color-heading);
  line-height: 1.25;
  margin-bottom: var(--space-4);
}
.article-meta {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  font-size: var(--text-sm);
  color: var(--color-muted);
}
.article-cover {
  width: 100%;
  max-height: 420px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-12);
  border: 1px solid var(--color-border);
}

/* Prose (article content) */
.prose {
  max-width: 720px;
  margin: 0 auto;
  color: var(--color-text);
}
.prose h1, .prose h2, .prose h3, .prose h4 {
  color: var(--color-heading);
  font-weight: 700;
  line-height: 1.3;
  margin-top: var(--space-12);
  margin-bottom: var(--space-4);
}
.prose h2 { font-size: var(--text-2xl); border-bottom: 1px solid var(--color-border); padding-bottom: var(--space-3); }
.prose h3 { font-size: var(--text-xl); }
.prose p { margin-bottom: var(--space-6); }
.prose ul, .prose ol { padding-left: var(--space-6); margin-bottom: var(--space-6); }
.prose li { margin-bottom: var(--space-2); }
.prose ul li { list-style: disc; }
.prose ol li { list-style: decimal; }
.prose blockquote {
  border-left: 3px solid var(--color-primary);
  padding: var(--space-4) var(--space-6);
  background: var(--color-surface);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: var(--space-8) 0;
  color: var(--color-muted);
  font-style: italic;
}
.prose code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--color-surface-2);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--color-accent);
}
.prose pre {
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
  overflow-x: auto;
  margin: var(--space-8) 0;
}
.prose pre code {
  background: none;
  padding: 0;
  color: var(--color-text);
  font-size: var(--text-sm);
}
.prose a { color: var(--color-primary); text-decoration: underline; text-underline-offset: 3px; }
.prose img { border-radius: var(--radius); margin: var(--space-8) auto; border: 1px solid var(--color-border); }
.prose table { width: 100%; border-collapse: collapse; margin: var(--space-8) 0; }
.prose th, .prose td { padding: var(--space-3) var(--space-4); border: 1px solid var(--color-border); text-align: left; }
.prose th { background: var(--color-surface-2); color: var(--color-heading); font-weight: 600; }
.prose hr { border: none; border-top: 1px solid var(--color-border); margin: var(--space-12) 0; }

/* ---------- Comments ---------- */
.comments-section {
  max-width: 720px;
  margin: var(--space-16) auto 0;
  padding-top: var(--space-12);
  border-top: 1px solid var(--color-border);
}
.comments-title {
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--space-8);
}

/* ---------- Footer ---------- */
.footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-12) 0;
  margin-top: var(--space-24);
}
.footer .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-4);
}
.footer-brand { font-weight: 700; color: var(--color-heading); }
.footer-copy { font-size: var(--text-sm); color: var(--color-muted); }
.footer-social { display: flex; gap: var(--space-4); }
.footer-social a { color: var(--color-muted); font-size: var(--text-sm); transition: color var(--transition); }
.footer-social a:hover { color: var(--color-primary); }

/* ---------- Pagination ---------- */
.pagination {
  display: flex;
  justify-content: center;
  gap: var(--space-2);
  margin-top: var(--space-12);
}
.page-btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  color: var(--color-muted);
  font-size: var(--text-sm);
  transition: all var(--transition);
  cursor: pointer;
}
.page-btn.active, .page-btn:hover {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

/* ---------- Back to Top ---------- */
.back-to-top {
  position: fixed;
  bottom: var(--space-8);
  right: var(--space-8);
  width: 44px;
  height: 44px;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-lg);
  box-shadow: 0 4px 20px rgba(108,99,255,0.4);
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
}
.back-to-top.visible { opacity: 1; pointer-events: auto; }
.back-to-top:hover { transform: translateY(-3px); color: #fff; }

/* ---------- Utility ---------- */
.text-muted { color: var(--color-muted); }
.text-accent { color: var(--color-accent); }
.mt-auto { margin-top: auto; }
.hidden { display: none !important; }

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .hero .container { grid-template-columns: 1fr; text-align: center; }
  .hero h1 { font-size: var(--text-3xl); }
  .hero-avatar { width: 150px; height: 150px; margin: 0 auto; }
  .hero-subtitle { margin: 0 auto var(--space-8); }
  .hero-actions { justify-content: center; }
  .hero-highlights { justify-content: center; }
  .hero-avatar { order: -1; }

  .navbar-links { display: none; position: absolute; top: 64px; left: 0; right: 0; background: var(--color-surface); padding: var(--space-6); flex-direction: column; border-bottom: 1px solid var(--color-border); }
  .navbar-links.open { display: flex; }
  .hamburger { display: flex; }

  .blog-card { grid-template-columns: 1fr; }
  .blog-card-img { height: 180px; }

  .section-title { font-size: var(--text-2xl); }
  .article-title { font-size: var(--text-2xl); }
  .footer .container { flex-direction: column; text-align: center; }
  section { padding: var(--space-16) 0; }
}

@media (max-width: 480px) {
  .container { padding: 0 var(--space-4); }
  .projects-grid { grid-template-columns: 1fr; }
  .tech-grid { grid-template-columns: 1fr; }
}