/* ==========================================================================
   Base — reset, document defaults, shared type helpers and layout primitives.
   ========================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

html {
  scroll-padding-top: 76px;
  transition: background 0.3s, color 0.3s;
}

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background 0.3s, color 0.3s;
}

::selection {
  background: var(--ink);
  color: var(--paper);
}

/* --------------------------------------------------------------------------
   Layout primitives
   -------------------------------------------------------------------------- */

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

section {
  padding: 90px 0;
  border-bottom: 1px solid var(--rule);
}

/* --------------------------------------------------------------------------
   Type helpers
   -------------------------------------------------------------------------- */

.label {
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.accent {
  color: var(--accent);
}

/* --------------------------------------------------------------------------
   Scroll reveal

   Sections start collapsed to zero height so they take up no space until
   `reveal-setup` is applied by scripts/reveal.js — this keeps the page short
   enough that the notebook intro is the only thing on screen at load.
   -------------------------------------------------------------------------- */

[data-reveal]:not(.reveal-setup) {
  height: 0;
  min-height: 0;
  overflow: hidden;
  padding-top: 0;
  padding-bottom: 0;
  border-bottom: none;
  margin: 0;
}

[data-reveal] {
  opacity: 0;
  transform: translateY(56px);
  transition: opacity 0.9s cubic-bezier(0.16, 1, 0.3, 1),
    transform 0.9s cubic-bezier(0.16, 1, 0.3, 1);
}

[data-reveal].revealed {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  [data-reveal] {
    transition: none;
    transform: none;
  }
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (max-width: 800px) {
  .wrap {
    padding: 0 var(--gutter-sm);
  }

  section {
    padding: 64px 0;
  }
}