/* WEB_STEP_02_01 — shared responsive layout, type and technical surfaces. */

:root {
  --rai-columns: 4;
  --rai-gutter: 16px;
  --rai-margin: 20px;

  --rai-space-4: 4px;
  --rai-space-8: 8px;
  --rai-space-12: 12px;
  --rai-space-16: 16px;
  --rai-space-22: 22px;
  --rai-space-32: 32px;
  --rai-space-44: 44px;
  --rai-space-64: 64px;

  --rai-line-width: 1px;
  --rai-motion-state: 120ms;
  --rai-motion-reveal: 180ms;
  --rai-motion-block: 240ms;
}

.rai-container {
  box-sizing: border-box;
  inline-size: 100%;
  max-inline-size: none;
  margin-inline: auto;
  padding-inline: var(--rai-margin);
}

.rai-layout {
  box-sizing: border-box;
  min-inline-size: 0;
  overflow-wrap: anywhere;
  hyphens: auto;
}

.rai-layout *,
.rai-layout *::before,
.rai-layout *::after {
  box-sizing: inherit;
  min-inline-size: 0;
}

.rai-grid {
  display: grid;
  grid-template-columns: repeat(var(--rai-columns), minmax(0, 1fr));
  gap: var(--rai-gutter);
}

.rai-stack > * + * {
  margin-block-start: var(--rai-space-32);
}

.rai-cluster {
  display: flex;
  flex-wrap: wrap;
  gap: var(--rai-space-16);
}

.rai-title {
  font-family: var(--font-display);
  font-size: clamp(56px, 4vw + 40px, 72px);
  font-weight: var(--weight-display-light);
  letter-spacing: -0.015em;
  line-height: 1.02;
  max-inline-size: 18ch;
}

.rai-heading {
  font-family: var(--font-display);
  font-size: clamp(32px, 1vw + 28px, 36px);
  font-weight: var(--weight-display-regular);
  line-height: 1.12;
  max-inline-size: 28ch;
}

.rai-ui {
  font-family: var(--font-display);
  font-size: clamp(22px, 1vw + 18px, 26px);
  font-weight: var(--weight-display-medium);
  line-height: 1.2;
}

.rai-lead {
  font-family: var(--font-body);
  font-size: clamp(19px, 0.25vw + 18px, 20px);
  font-weight: var(--weight-body);
  line-height: 1.6;
  max-inline-size: 70ch;
}

.rai-body {
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: var(--weight-body);
  line-height: 1.75;
  max-inline-size: 70ch;
}

.rai-section-number {
  color: color-mix(in oklab, var(--accent) 72%, var(--bg));
  font-family: var(--font-display);
  font-size: clamp(48px, 5vw, 72px);
  font-weight: var(--weight-display-semibold);
  line-height: 1;
}

.rai-meta,
.rai-caption {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: var(--weight-mono);
  letter-spacing: 0.08em;
  line-height: 1.4;
}

.rai-meta {
  font-size: clamp(10px, 0.25vw + 9px, 13px);
  text-transform: uppercase;
}

.rai-caption {
  color: var(--inkSoft);
}

.rai-rule {
  border: 0;
  border-block-start: var(--rai-line-width) solid var(--line);
  margin: 0;
}

.rai-panel {
  background: var(--panel);
}

.rai-placeholder {
  background: repeating-linear-gradient(
    118deg,
    var(--stripeA) 0,
    var(--stripeA) 9px,
    var(--stripeB) 9px,
    var(--stripeB) 18px
  );
  color: var(--inkSoft);
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.4;
  padding: var(--rai-space-16);
}

.rai-state {
  transition: color var(--rai-motion-state) linear, background-color var(--rai-motion-state) linear,
    border-color var(--rai-motion-state) linear;
}

.rai-reveal {
  transition: transform var(--rai-motion-reveal) ease-out;
}

.rai-block-transition {
  transition: transform var(--rai-motion-block) ease-out;
}

@media (min-width: 768px) {
  :root {
    --rai-columns: 8;
    --rai-gutter: 20px;
    --rai-margin: 28px;
  }
}

@media (min-width: 1024px) {
  :root {
    --rai-columns: 12;
    --rai-gutter: 24px;
    --rai-margin: 40px;
  }
}

@media (min-width: 1280px) {
  :root {
    --rai-margin: 56px;
  }
}

@media (prefers-reduced-motion: reduce) {
  :root {
    --rai-motion-state: 0ms;
    --rai-motion-reveal: 0ms;
    --rai-motion-block: 0ms;
  }
}