/* =============================================================================
   The track (views/partials/track.php): a sequence set on a rail, each step a
   slanted red node, its number in light red figures, a title and a line.
   Quality & Trust sets its four checks on it (in the order a unit meets them),
   About its six production steps (from drawing to dispatch).

   Wide: the rail runs along the top and the steps stand under it. Narrow: the
   rail stands up the inline-start edge, a timeline. A long track (six steps)
   keeps one row only where each step has room; between, it sets two rows of
   three, each step on a hairline of its own.
   ========================================================================== */

.track {
  --node-w: 0.625rem;
  --node-h: 1.125rem;
  --track-bg: var(--eme-bg-alt);
  --track-rail: var(--eme-line-strong);
  --track-muted: var(--eme-graphite);
  position: relative;
}
.track--dark {
  --track-bg: var(--eme-night);
  --track-rail: rgba(255, 255, 255, 0.18);
  --track-muted: rgba(255, 255, 255, 0.64);
  color: var(--eme-white);
}
.track__rail {
  position: absolute;
  inset-inline: 0;
  inset-block-start: calc(var(--node-h) / 2);
  block-size: 1px;
  background: var(--track-rail);
  pointer-events: none;
}
.track__fill {
  position: absolute;
  inset-inline: 0;
  inset-block: -0.5px;
  background: linear-gradient(
    90deg,
    var(--eme-red-ink) 0%,
    var(--eme-red) 38%,
    var(--eme-ember) 78%,
    transparent 100%
  );
  transform-origin: left center;
}
html[dir="rtl"] .track__fill {
  background: linear-gradient(
    270deg,
    var(--eme-red-ink) 0%,
    var(--eme-red) 38%,
    var(--eme-ember) 78%,
    transparent 100%
  );
  transform-origin: right center;
}
.track__list {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 1rem + 2vw, 3rem);
  margin: 0;
  padding: 0;
  list-style: none;
}
.track__step {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  min-inline-size: 0;
}
.track__node {
  display: block;
  inline-size: var(--node-w);
  block-size: var(--node-h);
  background: var(--eme-red);
  box-shadow: 0 0 0 5px var(--track-bg);
  transform: skewX(var(--eme-slant));
}
.track__num {
  margin-block-start: clamp(1.25rem, 1rem + 1vw, 2rem);
  font-size: clamp(2.25rem, 1.6rem + 2vw, 3.5rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--eme-red);
  font-variant-numeric: tabular-nums;
  font-family: var(--eme-font-latin);
}
.track__title {
  margin: clamp(0.9rem, 0.7rem + 0.6vw, 1.25rem) 0 0;
  font-size: var(--eme-step-2);
  font-weight: 600;
  line-height: 1.3;
}
.track__body {
  max-inline-size: 40ch;
  margin: 0.6rem 0 0;
  color: var(--track-muted);
}

/* Narrow: the rail stands up the inline-start edge, a timeline. */
@media (max-width: 63.99rem) {
  .track__rail {
    inset-inline: calc(var(--node-w) / 2) auto;
    inset-block: calc(var(--node-h) / 2) 0;
    inline-size: 1px;
    block-size: auto;
  }
  .track__fill,
  html[dir="rtl"] .track__fill {
    inset-block: 0;
    inset-inline: -0.5px;
    background: linear-gradient(
      180deg,
      var(--eme-red-ink) 0%,
      var(--eme-red) 30%,
      var(--eme-ember) 70%,
      transparent 100%
    );
    transform-origin: center top;
  }
  .track__list {
    grid-auto-flow: row;
    grid-template-columns: minmax(0, 1fr);
    row-gap: clamp(2rem, 1.5rem + 2vw, 3rem);
  }
  .track__step {
    display: grid;
    grid-template-columns: var(--node-w) auto minmax(0, 1fr);
    column-gap: clamp(1rem, 0.7rem + 1.2vw, 1.75rem);
    align-items: start;
  }
  .track__node {
    grid-column: 1;
    grid-row: 1;
  }
  .track__num {
    grid-column: 2;
    grid-row: 1 / span 2;
    min-inline-size: 2.2ch;
    margin: 0;
    font-size: clamp(1.75rem, 1.4rem + 1.5vw, 2.5rem);
  }
  .track__title {
    grid-column: 3;
    grid-row: 1;
    margin: 0;
  }
  .track__body {
    grid-column: 3;
    grid-row: 2;
  }
}

/* A long track on a laptop: two rows of three. The one rail would run under
   the first row only, so each step stands on a hairline of its own instead. */
@media (min-width: 64rem) and (max-width: 84.99rem) {
  .track--long .track__rail {
    display: none;
  }
  .track--long .track__list {
    grid-auto-flow: row;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    row-gap: clamp(2.5rem, 2rem + 2vw, 3.5rem);
  }
  .track--long .track__step::before {
    content: "";
    position: absolute;
    inset-inline: 0;
    inset-block-start: calc(var(--node-h) / 2);
    block-size: 1px;
    background: linear-gradient(90deg, var(--track-rail), transparent);
    z-index: -1;
  }
  html[dir="rtl"] .track--long .track__step::before {
    background: linear-gradient(270deg, var(--track-rail), transparent);
  }
  .track--long .track__list {
    isolation: isolate;
  }
}

/* Arrival (site.js arms a section only when it starts below the fold; without
   motion it stands as rendered): the rail runs out, then each step lands. */
.is-armed .track__fill {
  transform: scaleX(0);
}
.is-armed .track.is-in .track__fill {
  transform: none;
  transition: transform 1600ms var(--eme-ease-out) 150ms;
}
.is-armed .track__step {
  opacity: 0;
  transform: translate3d(0, 1rem, 0);
}
.is-armed .track__step.is-in {
  opacity: 1;
  transform: none;
  transition:
    opacity 700ms var(--eme-ease-out) calc(var(--d, 0) * 180ms + 250ms),
    transform 900ms var(--eme-ease-out) calc(var(--d, 0) * 180ms + 250ms);
}
@media (min-width: 64rem) {
  .track__step {
    --d: var(--i, 0);
  }
  .track--long .track__step {
    --d: calc(var(--i, 0) - 3 * round(down, var(--i, 0) / 3));
  }
}
@media (min-width: 85rem) {
  .track--long .track__step {
    --d: var(--i, 0);
  }
}
@media (max-width: 63.99rem) {
  .is-armed .track__fill {
    transform: scaleY(0);
  }
}