/* === Variables === */
:root {
  --color-bg: #0a0a0f;
  --color-bg-elevated: #12121a;
  --color-bg-card: #1a1a24;
  --color-border: #2a2a3a;
  --color-text: #e4e4e7;
  --color-text-muted: #a1a1aa;
  --color-primary: #6366f1;
  --color-primary-hover: #818cf8;
  --color-accent: #22d3ee;
  --color-success: #34d399;
  --color-warning: #fbbf24;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --radius: 8px;
  --max-width: 1200px;
}

/* === 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: 1.6;
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
}

/* === Header === */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 15, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.25rem;
}

.logo-icon {
  font-size: 1.5rem;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: var(--color-text-muted);
  font-weight: 500;
  transition: color 0.2s;
}

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

.nav-cta {
  background: var(--color-primary);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-weight: 500;
  transition: background 0.2s;
}

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

/* === Main Content === */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

/* === Hero Section === */
.hero {
  text-align: center;
  padding: 4rem 0;
  margin-bottom: 3rem;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--color-text) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

.hero-cta {
  display: inline-flex;
  gap: 1rem;
}

.btn {
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
}

.btn-primary:hover {
  background: var(--color-primary-hover);
  transform: translateY(-2px);
}

.btn-secondary {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  color: var(--color-text);
}

.btn-secondary:hover {
  border-color: var(--color-primary);
}

/* === Section Headers === */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.section-header h2 {
  font-size: 1.5rem;
  font-weight: 700;
}

.section-header a {
  color: var(--color-primary);
  font-weight: 500;
}

/* === Cards Grid === */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all 0.2s;
}

.card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.card-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  margin-bottom: 0.75rem;
}

.tag-paper { background: rgba(99, 102, 241, 0.2); color: var(--color-primary); }
.tag-tool { background: rgba(34, 211, 238, 0.2); color: var(--color-accent); }
.tag-news { background: rgba(251, 191, 36, 0.2); color: var(--color-warning); }
.tag-job { background: rgba(52, 211, 153, 0.2); color: var(--color-success); }

.card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.card p {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 1rem;
}

.card-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

/* === Newsletter Section === */
.newsletter-section {
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 3rem;
  text-align: center;
  margin: 3rem 0;
}

.newsletter-section h2 {
  font-size: 1.75rem;
  margin-bottom: 0.5rem;
}

.newsletter-section p {
  color: var(--color-text-muted);
  margin-bottom: 1.5rem;
}

.newsletter-form {
  display: flex;
  gap: 0.5rem;
  max-width: 400px;
  margin: 0 auto;
}

.newsletter-form input {
  flex: 1;
  padding: 0.75rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  font-size: 1rem;
}

.newsletter-form input:focus {
  outline: none;
  border-color: var(--color-primary);
}

/* === Footer === */
.site-footer {
  border-top: 1px solid var(--color-border);
  margin-top: 4rem;
  padding: 3rem 1.5rem;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 3rem;
  margin-bottom: 2rem;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-tagline {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  gap: 4rem;
}

.footer-col {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-col h4 {
  font-weight: 600;
  margin-bottom: 0.5rem;
}

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

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

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

/* === Responsive === */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .hero h1 { font-size: 2rem; }
  .cards-grid { grid-template-columns: 1fr; }
  .footer-container { flex-direction: column; }
  .newsletter-form { flex-direction: column; }
}