/* ============================================================
   Tjerk Spijkman — personal site
   Single stylesheet, no dependencies. Safe for static hosting.
   ============================================================ */

:root {
  --bg: #0b0d12;
  --bg-soft: #12151d;
  --card: #161a24;
  --card-border: #232838;
  --text: #e7eaf0;
  --text-dim: #9aa3b2;
  --accent: #7c9cff;
  --accent-2: #58e6c9;
  --radius: 16px;
  --maxw: 1040px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f8fc;
    --bg-soft: #ffffff;
    --card: #ffffff;
    --card-border: #e4e8f0;
    --text: #1b2130;
    --text-dim: #5a6478;
    --accent: #3b5bff;
    --accent-2: #0fae8c;
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* --- decorative background --- */
.bg-grid {
  position: fixed;
  inset: 0;
  z-index: -2;
  background-image:
    linear-gradient(to right, rgba(124,156,255,0.06) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(124,156,255,0.06) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse at 50% 0%, #000 30%, transparent 80%);
}
.bg-glow {
  position: fixed;
  top: -20%;
  left: 50%;
  transform: translateX(-50%);
  width: 900px;
  height: 600px;
  z-index: -1;
  background: radial-gradient(circle at 50% 50%, rgba(124,156,255,0.25), transparent 60%);
  filter: blur(40px);
  pointer-events: none;
}

/* --- header --- */
.site-header {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 24px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  text-decoration: none;
  color: var(--text);
  font-size: 1.05rem;
}
.brand-mark { font-size: 1.3rem; }
.site-nav { display: flex; gap: 22px; flex-wrap: wrap; }
.site-nav a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.15s ease;
}
.site-nav a:hover { color: var(--accent); }

/* --- layout --- */
main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

/* --- hero --- */
.hero {
  padding: 72px 0 64px;
  text-align: center;
}
.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.75rem;
  color: var(--accent);
  font-weight: 600;
  margin: 0 0 18px;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.12;
  margin: 0 auto 24px;
  max-width: 18ch;
  letter-spacing: -0.02em;
}
.accent {
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.lead {
  font-size: clamp(1rem, 2vw, 1.18rem);
  color: var(--text-dim);
  max-width: 60ch;
  margin: 0 auto 32px;
}
.lead strong { color: var(--text); }

.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  transition: transform 0.12s ease, box-shadow 0.2s ease, background 0.2s ease;
}
.btn-primary {
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  color: #06121f;
  box-shadow: 0 8px 24px rgba(124,156,255,0.35);
}
.btn-primary:hover { transform: translateY(-2px); }
.btn-ghost {
  color: var(--text);
  border: 1px solid var(--card-border);
  background: var(--bg-soft);
}
.btn-ghost:hover { transform: translateY(-2px); border-color: var(--accent); }

/* --- sections --- */
.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}
.section-sub {
  color: var(--text-dim);
  margin: 0 0 32px;
}
.cards-section { padding: 56px 0; }
.cards-section.alt {
  border-top: 1px solid var(--card-border);
  border-bottom: 1px solid var(--card-border);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
}
.card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 26px 24px;
  transition: transform 0.15s ease, border-color 0.2s ease;
}
.card:hover { transform: translateY(-4px); border-color: var(--accent); }
.card-link { text-decoration: none; color: inherit; display: block; }
.card-link h3 { color: var(--accent); }
.card-icon { font-size: 1.8rem; margin-bottom: 12px; }
.card h3 { margin: 0 0 8px; font-size: 1.15rem; }
.card p { margin: 0; color: var(--text-dim); font-size: 0.96rem; }

/* --- about --- */
.about {
  padding: 64px 0 40px;
  max-width: 62ch;
}
.about p { color: var(--text-dim); font-size: 1.05rem; }

/* --- footer --- */
.site-footer {
  border-top: 1px solid var(--card-border);
  margin-top: 40px;
  padding: 32px 24px;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.9rem;
}

@media (max-width: 560px) {
  .hero { padding: 48px 0 40px; }
  .site-header { justify-content: center; }
}