/* layout.css — Grid systems, section structure, responsive breakpoints */

/* Base body */
body {
  background-color: var(--void-deep);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
}

/* Animated starfield canvas (injected by js/starfield.js) — fixed behind
   everything; sections paint translucent scrims over it */
.starfield {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  pointer-events: none;
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  z-index: 10000; /* Must be above grain overlay (z-index: 9999) */
  padding: var(--space-sm) var(--space-md);
  background: var(--void-elevated);
  color: var(--singularity-glow);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

.skip-link:focus {
  top: var(--space-md);
}

/* Section containers */
section {
  position: relative;
  width: 100%;
  padding-top: var(--space-section);
  padding-bottom: var(--space-section);
}

/* Hero is special — full viewport, no top padding */
#signal {
  min-height: 100vh;
  padding-top: 0;
  padding-bottom: 0;
}

/* Content wrapper — constrains inner content */
.section__inner {
  width: 100%;
  max-width: 75rem; /* 1200px */
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}

/* Narrow content for readability (body text blocks) */
.section__inner--narrow {
  max-width: 50rem; /* 800px */
}

/* Grid utilities */
.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
}

.grid--2 {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
}

.grid--4 {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
}

/* Tablet (640px) */
@media (min-width: 640px) {
  .section__inner {
    padding-left: var(--space-xl);
    padding-right: var(--space-xl);
  }

  .grid--2 {
    grid-template-columns: repeat(2, 1fr);
  }

  .grid--4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Desktop (1024px) */
@media (min-width: 1024px) {
  section {
    padding-top: var(--space-section);
    padding-bottom: var(--space-section);
  }

  .section__inner {
    padding-left: var(--space-3xl);
    padding-right: var(--space-3xl);
  }

  .grid--4 {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* Wide desktop (1440px) */
@media (min-width: 1440px) {
  .section__inner {
    max-width: 80rem; /* 1280px */
  }
}

/* Section header typography */
.section__header {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-wide);
  color: var(--text-primary);
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section__closing {
  font-family: var(--font-body);
  font-size: var(--text-lg);
  font-style: italic;
  color: var(--text-secondary);
  text-align: center;
  margin-top: var(--space-3xl);
}

/* Reduce section spacing on mobile */
@media (max-width: 639px) {
  section {
    padding-top: var(--space-3xl);
    padding-bottom: var(--space-3xl);
  }

  .section__header {
    font-size: var(--text-xl);
    margin-bottom: var(--space-2xl);
  }

  .section__closing {
    margin-top: var(--space-2xl);
  }
}

@media (min-width: 640px) {
  .section__header {
    font-size: var(--text-3xl);
  }
}