/* =============================================================================
   NEXUS — Components
   Every rule below is structural. Colour, border and space carry the design;
   nothing is decorative.
   ========================================================================== */

@layer components {
  /* =====================================================================
     Typography components
     ================================================================== */
  .eyebrow {
    margin: 0;
    color: var(--color-text-subtle);
    font-size: var(--text-xs);
    font-weight: var(--weight-medium);
    letter-spacing: var(--tracking-widest);
    text-transform: uppercase;
  }

  .display {
    font-size: var(--text-5xl);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-tight);
    letter-spacing: var(--tracking-tighter);
  }

  .heading-2 {
    font-size: var(--text-3xl);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-snug);
    letter-spacing: var(--tracking-tight);
  }

  .heading-3 {
    font-size: var(--text-xl);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-snug);
    letter-spacing: var(--tracking-tight);
  }

  .heading-4 {
    font-size: var(--text-md);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-snug);
  }

  .lede {
    max-inline-size: var(--width-prose);
    color: var(--color-text-muted);
    font-size: var(--text-lg);
    line-height: var(--leading-relaxed);
  }

  .prose {
    max-inline-size: var(--width-prose);
    color: var(--color-text-muted);
  }

  /* =====================================================================
     Section header — eyebrow, heading, supporting line
     ================================================================== */
  .section-head {
    --stack-gap: var(--space-4);
    max-inline-size: var(--width-narrow);
    margin-block-end: var(--space-12);
  }

  /* =====================================================================
     Button
     One geometry, three weights of emphasis. Borders are present on every
     variant so the box metrics never change between them.
     ================================================================== */
  .button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    min-block-size: 2.75rem;
    padding-inline: var(--space-5);
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    line-height: var(--leading-none);
    text-align: center;
    text-decoration: none;
    transition: background-color var(--duration-fast) var(--ease-standard),
      border-color var(--duration-fast) var(--ease-standard),
      color var(--duration-fast) var(--ease-standard);
  }

  .button:active {
    transform: translate3d(0, 1px, 0);
  }

  .button[data-variant="primary"] {
    background-color: var(--color-accent-solid);
    color: var(--color-on-accent);
  }

  .button[data-variant="primary"]:hover {
    background-color: var(--color-accent-solid-hover);
  }

  .button[data-variant="secondary"] {
    border-color: var(--color-border-strong);
    color: var(--color-text);
  }

  .button[data-variant="secondary"]:hover {
    background-color: var(--color-surface-raised);
  }

  .button[data-variant="ghost"] {
    padding-inline: var(--space-3);
    color: var(--color-text-muted);
  }

  .button[data-variant="ghost"]:hover {
    color: var(--color-text);
  }

  .button[data-size="lg"] {
    min-block-size: 3rem;
    padding-inline: var(--space-6);
    font-size: var(--text-base);
  }

  /* Directional affordance on links that leave the section. */
  .button__arrow {
    inline-size: 0.875em;
    block-size: 0.875em;
    transition: transform var(--duration-fast) var(--ease-standard);
  }

  .button:hover .button__arrow {
    transform: translate3d(2px, 0, 0);
  }

  /* =====================================================================
     Header — primary navigation
     ================================================================== */
  .header-actions {
    --cluster-gap: var(--space-2);
    flex-wrap: nowrap;
  }

  .nav {
    position: absolute;
    inset-block-start: 100%;
    inset-inline: 0;
    display: none;
    padding: var(--space-4) var(--gutter) var(--space-6);
    background-color: var(--color-canvas);
    border-block-end: 1px solid var(--color-border);
  }

  .nav[data-open="true"] {
    display: block;
  }

  .nav__list {
    --stack-gap: var(--space-1);
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .nav__link {
    display: block;
    padding-block: var(--space-3);
    color: var(--color-text-muted);
    font-size: var(--text-base);
    text-decoration: none;
    transition: color var(--duration-fast) var(--ease-standard);
  }

  .nav__link:hover {
    color: var(--color-text);
  }

  .nav__cta {
    margin-block-start: var(--space-4);
  }

  .menu-button {
    display: inline-grid;
    place-items: center;
    inline-size: 2.25rem;
    block-size: 2.25rem;
    border-radius: var(--radius-full);
    color: var(--color-text-muted);
    transition: color var(--duration-fast) var(--ease-standard),
      background-color var(--duration-fast) var(--ease-standard);
  }

  .menu-button:hover {
    background-color: var(--color-surface-raised);
    color: var(--color-text);
  }

  .menu-button__icon {
    grid-area: 1 / 1;
    inline-size: 1.25rem;
    block-size: 1.25rem;
  }

  .menu-button[aria-expanded="false"] .menu-button__icon[data-icon="close"],
  .menu-button[aria-expanded="true"] .menu-button__icon[data-icon="open"] {
    display: none;
  }

  /* =====================================================================
     Hero
     ================================================================== */
  .hero {
    padding-block: calc(var(--space-section) + var(--space-8))
      var(--space-section);
  }

  .hero__inner {
    --stack-gap: var(--space-6);
    max-inline-size: var(--width-narrow);
  }

  .hero__actions {
    --cluster-gap: var(--space-3);
    margin-block-start: var(--space-2);
  }

  .hero__note {
    color: var(--color-text-subtle);
    font-size: var(--text-sm);
  }

  /* =====================================================================
     Card — shared by recognition, scope and case surfaces
     ================================================================== */
  .card {
    --stack-gap: var(--space-3);
    padding: var(--space-6);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
  }

  .card__body {
    color: var(--color-text-muted);
    font-size: var(--text-base);
  }

  /* =====================================================================
     Steps — the method, in order
     ================================================================== */
  .steps {
    --grid-min: 15rem;
    --grid-gap: var(--space-8);
    margin: 0;
    padding: 0;
    counter-reset: step;
    list-style: none;
  }

  .step {
    --stack-gap: var(--space-3);
    padding-block-start: var(--space-5);
    border-block-start: 1px solid var(--color-border);
    counter-increment: step;
  }

  .step::before {
    content: counter(step, decimal-leading-zero);
    color: var(--color-accent);
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    font-variant-numeric: tabular-nums;
    letter-spacing: var(--tracking-wide);
  }

  .step__body {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: var(--leading-relaxed);
  }

  /* =====================================================================
     Case — proof
     ================================================================== */
  .case {
    --stack-gap: var(--space-8);
    padding: var(--space-6);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
  }

  .case__header {
    --stack-gap: var(--space-3);
  }

  .case__meta {
    --cluster-gap: var(--space-3);
    color: var(--color-text-subtle);
    font-size: var(--text-sm);
  }

  .case__note {
    --stack-gap: var(--space-4);
  }

  .case__meta li + li::before {
    content: "";
    display: inline-block;
    inline-size: 3px;
    block-size: 3px;
    margin-inline-end: var(--space-3);
    border-radius: var(--radius-full);
    background-color: var(--color-text-subtle);
    vertical-align: middle;
  }

  .metrics {
    --grid-min: 9rem;
    --grid-gap: var(--space-6);
    margin: 0;
    padding-block-start: var(--space-6);
    border-block-start: 1px solid var(--color-border);
  }

  /* Value above label, with the source order a definition list requires. */
  .metric {
    display: flex;
    flex-direction: column-reverse;
    gap: var(--space-1);
  }

  .metric__value {
    font-size: var(--text-3xl);
    font-weight: var(--weight-semibold);
    font-variant-numeric: tabular-nums;
    letter-spacing: var(--tracking-tight);
    line-height: var(--leading-none);
  }

  .metric__label {
    margin: 0;
    color: var(--color-text-subtle);
    font-size: var(--text-sm);
  }

  /* =====================================================================
     Scope — two facing columns
     ================================================================== */
  .scope-grid {
    --grid-min: 20rem;
    --grid-gap: var(--space-8);
  }

  .scope-card {
    --stack-gap: var(--space-6);
  }

  /* =====================================================================
     Marked list — scope in, scope out
     ================================================================== */
  .marked-list {
    --stack-gap: var(--space-4);
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .marked-list li {
    display: grid;
    grid-template-columns: 0.75rem 1fr;
    gap: var(--space-4);
    align-items: baseline;
    color: var(--color-text-muted);
  }

  .marked-list li::before {
    content: "";
    inline-size: 0.5rem;
    block-size: 0.5rem;
    margin-inline-start: 0.125rem;
    border-radius: var(--radius-full);
    background-color: var(--color-accent);
    translate: 0 -0.1rem;
  }

  .marked-list[data-marker="excluded"] li::before {
    inline-size: 0.75rem;
    block-size: 1px;
    margin-inline-start: 0;
    border-radius: 0;
    background-color: var(--color-text-subtle);
    translate: 0 -0.25rem;
  }

  /* =====================================================================
     Terms — definition rows
     ================================================================== */
  .terms {
    margin: 0;
  }

  .terms__row {
    display: grid;
    gap: var(--space-2);
    padding-block: var(--space-5);
    border-block-start: 1px solid var(--color-border);
  }

  .terms__row dt {
    font-weight: var(--weight-medium);
  }

  .terms__row dd {
    margin: 0;
    color: var(--color-text-muted);
  }

  /* =====================================================================
     Final call to action
     ================================================================== */
  .cta {
    --stack-gap: var(--space-6);
    padding: var(--space-8) var(--space-6);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border-strong);
    border-radius: var(--radius-xl);
  }

  .cta__text {
    --stack-gap: var(--space-4);
    max-inline-size: var(--width-prose);
  }

  /* =====================================================================
     Footer
     ================================================================== */
  .footer-top {
    --grid-min: 12rem;
    --grid-gap: var(--space-10);
    padding-block: var(--space-16) var(--space-12);
  }

  .footer-brand {
    --stack-gap: var(--space-4);
  }

  .footer-brand p {
    max-inline-size: 22rem;
    color: var(--color-text-subtle);
    font-size: var(--text-sm);
  }

  .footer-nav {
    --stack-gap: var(--space-4);
  }

  .footer-nav h2 {
    color: var(--color-text-subtle);
    font-size: var(--text-xs);
    font-weight: var(--weight-medium);
    letter-spacing: var(--tracking-widest);
    text-transform: uppercase;
  }

  .footer-nav ul {
    --stack-gap: var(--space-3);
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .footer-nav a {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    text-decoration: none;
    transition: color var(--duration-fast) var(--ease-standard);
  }

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

  /* =====================================================================
     Viewport adaptations
     Mobile is the base. Each query adds only what the extra width earns.
     ================================================================== */
  @media (min-width: 40rem) {
    .display {
      font-size: var(--text-6xl);
    }

    .card,
    .case,
    .cta {
      padding: var(--space-8);
    }

    .terms__row {
      grid-template-columns: 13rem 1fr;
      gap: var(--space-8);
    }

    .cta {
      --stack-gap: var(--space-8);
      padding: var(--space-12);
    }
  }

  @media (min-width: 60rem) {
    .menu-button {
      display: none;
    }

    .nav {
      position: static;
      display: flex;
      align-items: center;
      gap: var(--space-2);
      margin-inline-start: auto;
      padding: 0;
      background-color: transparent;
      border: 0;
    }

    .nav__list {
      display: flex;
      align-items: center;
      gap: var(--space-1);
    }

    .nav__link {
      padding: var(--space-2) var(--space-3);
      border-radius: var(--radius-sm);
      font-size: var(--text-sm);
    }

    .nav__cta {
      margin-block-start: 0;
      margin-inline-start: var(--space-2);
    }

    .case {
      padding: var(--space-12);
    }

    .cta {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: var(--space-12);
    }
  }
}