/* Loading intro. Two classes on <html>, both set in <head> and removed by js/components/intro.js:
   .intro-on   overlay is shown, page scroll locked, real hero arcs hidden
   .intro-hold hero content is hidden until its reveal animation starts */
.intro {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 100;
  background: var(--color-dark-blue);
  color: var(--color-white);
  cursor: pointer;
}
.intro-on .intro { display: block; }
.intro-on { overflow: hidden; }

.intro__stage {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
}

/* Scales the fixed-size artwork down on narrow screens (--s is set from JS) */
.intro__fit { transform: scale(var(--s, 1)); }

/* Stage 1: tagline, revealed line by line through a mask */
.intro__tagline {
  max-width: min(564px, 90vw);
  font: 400 40px/44px var(--font-serif);
  text-align: center;
}
.intro__line {
  display: block;
  overflow: hidden;
  padding-bottom: 0.08em;
  margin-bottom: -0.08em;
}
.intro__line > span { display: block; transform: translateY(110%); will-change: transform; }

/* Stages 2-4: one SVG scene. Letters and the mark start hidden below their masks. */
.intro__scene { display: block; overflow: visible; }
.intro__lt { transform: translateY(100px); will-change: transform; }
.intro__lp { transform-origin: 0 0; }
.intro__sigin { transform: translateY(115px); will-change: transform; }
.intro__sig { transform-origin: 0 0; will-change: transform; }

/* Full-screen colour layer: fades from the intro colour to the page colour during the finale */
.intro__flood {
  position: absolute;
  inset: 0;
  background: var(--color-dark-blue);
  visibility: hidden;
  will-change: background-color;
}

/* Final stage: the mark's line pairs become the hero background. Same shapes as the hero's own arcs,
   scaled 8.14x from the mark. Each side has two stacked layers (start colour / end colour) that cross-fade,
   so the colour change is an opacity animation. */
.intro__arcs {
  position: absolute;
  top: 0;
  width: 646px;
  height: 912px;
  visibility: hidden;
  transform-origin: 0 0;
  will-change: transform;
}
.intro__arcs--left { left: -374px; }
.intro__arcs--right { left: calc(50% + 439px); }
.intro__arcs > i {
  position: absolute;
  inset: 0;
  will-change: opacity;
}
/* Left pair: the start-colour layer holds the two stripes separately (inner / outer) so they can differ */
.intro__arcs--left > i:last-child { -webkit-mask: url("../assets/images/hero-arcs-left.svg") center / 100% 100% no-repeat; mask: url("../assets/images/hero-arcs-left.svg") center / 100% 100% no-repeat; }
.intro__arcs--left > i > b { position: absolute; inset: 0; }
.intro__arcs--left > i > b:first-child { -webkit-mask: url("../assets/images/hero-arcs-left-inner.svg") center / 100% 100% no-repeat; mask: url("../assets/images/hero-arcs-left-inner.svg") center / 100% 100% no-repeat; }
.intro__arcs--left > i > b:last-child { -webkit-mask: url("../assets/images/hero-arcs-left-outer.svg") center / 100% 100% no-repeat; mask: url("../assets/images/hero-arcs-left-outer.svg") center / 100% 100% no-repeat; }
.intro__arcs--right > i { -webkit-mask: url("../assets/images/hero-arcs-right.svg") center / 100% 100% no-repeat; mask: url("../assets/images/hero-arcs-right.svg") center / 100% 100% no-repeat; }

/* Hero content stays hidden until the reveal animations take over */
.intro-hold .nav,
.intro-hold .hero__content,
.intro-hold .hero > .container,
.intro-hold .theme-toggle { opacity: 0; }

/* The page's own arcs appear only when the overlay copies land on them */
.intro-on .bg-arcs { opacity: 0; }

@media (prefers-reduced-motion: reduce) {
  .intro { display: none !important; }
}