:root {
  --snow: #f3f5f4;
  --ink: #14202b;
  --mist: #5d6c77;
  --glacier: #dbe4e7;
  --fjord: #1f4e66;
  --fjord-deep: #163a4d;

  --font: "Jost", "Avenir Next", "Futura", "Helvetica Neue", Arial, sans-serif;
  --ease: cubic-bezier(.22, .8, .2, 1);
  --gutter: clamp(1.25rem, 5vw, 4rem);
  --max: 74rem;
}

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

html { scroll-behavior: smooth; scroll-padding-top: 5rem; }

body {
  margin: 0;
  background: var(--snow);
  color: var(--ink);
  font-family: var(--font);
  font-weight: 300;
  font-size: 1.125rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, p, ul, ol, figure { margin: 0; padding: 0; }
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }

:focus-visible {
  outline: 2px solid var(--fjord);
  outline-offset: 4px;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -4rem;
  background: var(--ink);
  color: var(--snow);
  padding: .5rem 1rem;
  z-index: 10;
}
.skip:focus { top: 1rem; }

/* ---------- Navigation ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem max(var(--gutter), calc((100% - var(--max)) / 2 + var(--gutter)));
  background: color-mix(in srgb, var(--snow) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid color-mix(in srgb, var(--glacier) 70%, transparent);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: .75rem;
  font-weight: 500;
  letter-spacing: .04em;
}

.mark {
  width: 1.75rem;
  height: 1.75rem;
  fill: none;
  stroke: var(--fjord);
  stroke-width: 7;
  stroke-linecap: square;
  stroke-linejoin: miter;
  overflow: visible;
}

.nav nav { display: flex; gap: 2rem; font-size: 1rem; }
.nav nav a {
  color: var(--mist);
  background: linear-gradient(var(--fjord), var(--fjord)) 0 100% / 0 1px no-repeat;
  padding-bottom: .2rem;
  transition: color .3s, background-size .4s var(--ease);
}
.nav nav a:hover { color: var(--ink); background-size: 100% 1px; }

/* ---------- Hero ---------- */
.hero {
  max-width: var(--max);
  margin: 0 auto;
  padding: clamp(3rem, 9vh, 7rem) var(--gutter) clamp(4rem, 12vh, 8rem);
  min-height: calc(100svh - 4.5rem);
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
  align-items: center;
  gap: clamp(2rem, 6vw, 6rem);
}

h1 {
  font-weight: 300;
  font-size: 4.25rem;
  line-height: 1.04;
  letter-spacing: -.02em;
}

.lede {
  margin-top: 2rem;
  max-width: 34rem;
  color: var(--mist);
  font-size: 1.25rem;
}

.actions {
  margin-top: 2.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  min-height: 3.25rem;
  padding: 0 1.75rem;
  font-weight: 400;
  font-size: 1rem;
  letter-spacing: .02em;
  border: 1px solid var(--fjord);
  transition: background-color .35s var(--ease), color .35s var(--ease), transform .35s var(--ease);
}
.btn:active { transform: translateY(1px); }

.btn-primary { background: var(--fjord); color: var(--snow); }
.btn-primary:hover { background: var(--fjord-deep); border-color: var(--fjord-deep); }

.btn-ghost { color: var(--fjord); }
.btn-ghost:hover { background: var(--fjord); color: var(--snow); }

/* Hero mark */
.hero-mark {
  position: relative;
  justify-self: center;
  width: min(100%, 26rem);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
}

.hero-mark svg {
  width: 100%;
  height: 100%;
  overflow: visible;
  fill: none;
  stroke: var(--fjord);
  stroke-width: 1.6;
  stroke-linecap: square;
  stroke-linejoin: miter;
}

/* Faint vertical vector rising from the arrow tip */
.vector {
  position: absolute;
  left: 50%;
  bottom: 91.7%;
  width: 1px;
  height: 120vh;
  background: linear-gradient(to top, var(--fjord), transparent 70%);
  transform-origin: bottom;
  transform: scaleY(0);
  opacity: .5;
  animation: vector 2.4s var(--ease) 2.2s forwards;
}

.sq {
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  animation: draw 1.8s var(--ease) .2s forwards;
}

.arrow {
  transform: translateY(18%);
  animation: rise 1.6s var(--ease) 1.5s forwards, float 7s ease-in-out 3.2s infinite;
}
.arrow .shaft, .arrow .head {
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  animation: draw 1.2s var(--ease) 1.4s forwards;
}
.arrow .head { animation-delay: 2.2s; animation-duration: .6s; }

@keyframes draw { to { stroke-dashoffset: 0; } }
@keyframes rise { to { transform: translateY(0); } }
@keyframes float { 50% { transform: translateY(-2.2%); } }
@keyframes vector { to { transform: scaleY(1); } }

/* Hero copy entrance */
.hero-copy > * {
  opacity: 0;
  transform: translateY(14px);
  animation: enter 1.1s var(--ease) forwards;
}
.hero-copy h1 { animation-delay: .1s; }
.hero-copy .lede { animation-delay: .35s; }
.hero-copy .actions { animation-delay: .55s; }
@keyframes enter { to { opacity: 1; transform: none; } }

/* ---------- Sections ---------- */
.section {
  max-width: var(--max);
  margin: 0 auto;
  padding: clamp(4rem, 12vh, 8rem) var(--gutter);
  border-top: 1px solid var(--glacier);
}

.section-head { max-width: 42rem; margin-bottom: clamp(2.5rem, 6vw, 4.5rem); }

h2 {
  font-weight: 300;
  font-size: 2.75rem;
  line-height: 1.12;
  letter-spacing: -.015em;
}
.section-head p { margin-top: 1.25rem; color: var(--mist); }

h3 { font-weight: 400; font-size: 1.375rem; line-height: 1.3; }

/* Symbol */
.symbol-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.3fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: center;
}

.diagram {
  width: min(100%, 18rem);
  justify-self: center;
  overflow: visible;
  fill: none;
  stroke-width: 1.6;
  stroke-linecap: square;
  stroke-linejoin: miter;
}
.d-sq, .d-ar {
  stroke: var(--fjord);
  transition: stroke .5s var(--ease), stroke-width .5s var(--ease), opacity .5s var(--ease);
}
.d-ar { transition-property: stroke, stroke-width, opacity, transform; }

.principles { border-top: 1px solid var(--glacier); }
.principle {
  padding: 2rem 0 2rem 1.5rem;
  border-bottom: 1px solid var(--glacier);
  border-left: 2px solid transparent;
  transition: border-color .4s var(--ease), padding-left .4s var(--ease);
}
.principle:hover, .principle:focus-visible { border-left-color: var(--fjord); padding-left: 2rem; }
.principle h3 span {
  margin-left: .75rem;
  font-size: .95rem;
  font-weight: 300;
  color: var(--mist);
}
.principle p { margin-top: .75rem; color: var(--mist); max-width: 32rem; }

/* Hovering a principle emphasises its half of the symbol */
.symbol-grid:has(.p-square:is(:hover, :focus-visible)) .d-sq { stroke-width: 3; }
.symbol-grid:has(.p-square:is(:hover, :focus-visible)) .d-ar { opacity: .25; }
.symbol-grid:has(.p-arrow:is(:hover, :focus-visible)) .d-ar { stroke-width: 3; transform: translateY(-4px); }
.symbol-grid:has(.p-arrow:is(:hover, :focus-visible)) .d-sq { opacity: .25; }

/* Pillars */
.pillars { counter-reset: pillar; border-top: 1px solid var(--glacier); }
.pillars li {
  counter-increment: pillar;
  display: grid;
  grid-template-columns: 4.5rem minmax(0, 1fr) minmax(0, 1.4fr);
  gap: 1.5rem;
  align-items: baseline;
  padding: 2rem 0;
  border-bottom: 1px solid var(--glacier);
}
.pillars li::before {
  content: counter(pillar);
  font-size: 2.5rem;
  font-weight: 300;
  line-height: 1;
  color: var(--fjord);
}
.pillars p { color: var(--mist); }

/* Architecture */
.columns {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(1.5rem, 4vw, 3.5rem);
}
.columns article { border-top: 2px solid var(--fjord); padding-top: 1.5rem; }
.columns p { margin-top: .75rem; color: var(--mist); }

/* ---------- Footer ---------- */
.footer {
  background: var(--ink);
  color: var(--snow);
  text-align: center;
  padding: clamp(4rem, 10vh, 6rem) var(--gutter);
}
.footer .mark { width: 2.5rem; height: 2.5rem; stroke: var(--glacier); margin-bottom: 1.5rem; }
.footer h2 { font-size: 2rem; }
.footer p { margin-top: .75rem; color: #a9b8c1; }

/* ---------- Scroll reveal (progressive enhancement) ---------- */
@supports (animation-timeline: view()) {
  .reveal {
    opacity: 0;
    transform: translateY(24px);
    animation: enter linear both;
    animation-timeline: view();
    animation-range: entry 5% cover 28%;
  }
}

/* ---------- Responsive ---------- */
@media (max-width: 62rem) {
  h1 { font-size: 3.25rem; }
  h2 { font-size: 2.25rem; }
  .hero { grid-template-columns: 1fr; min-height: 0; }
  .hero-mark { width: min(70%, 20rem); order: -1; }
  .vector { display: none; }
  .symbol-grid { grid-template-columns: 1fr; }
  .columns { grid-template-columns: 1fr; }
  .pillars li { grid-template-columns: 3rem 1fr; }
  .pillars li p { grid-column: 2; }
}

@media (max-width: 40rem) {
  body { font-size: 1.0625rem; }
  h1 { font-size: 2.5rem; }
  h2 { font-size: 1.875rem; }
  .nav nav { display: none; }
  .actions .btn { width: 100%; justify-content: center; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
  .sq, .arrow, .arrow .shaft, .arrow .head, .vector, .hero-copy > *, .reveal {
    animation: none !important;
    opacity: 1;
    transform: none;
    stroke-dashoffset: 0;
  }
  .vector { transform: scaleY(1); }
}