/* Prism case study.
   Design premise: the renderer's own backdrop is a flat #222326, so the page is
   that exact colour and the hero frame has no edge, so the stone floats in the
   page instead of sitting in a box. Everything else is hairlines and one
   spectral rule, because dispersion is what the project is about. */

:root {
  --bg:          #222326;   /* must equal the render's backdrop, or the seam shows */
  --ink:         #f3f1ed;
  --ink-soft:    #c8c5bf;
  --muted:       #918d87;
  --rule:        rgba(255, 255, 255, 0.10);
  --rule-strong: rgba(255, 255, 255, 0.20);
  --link:        #6fe0cf;
  --code:        #f0d9a0;

  --s1: #8f74ff;  --s2: #5b9dff;  --s3: #4fd9c8;
  --s4: #a9e05f;  --s5: #ffca5c;  --s6: #ff7b6b;
  --spectrum: linear-gradient(92deg,
    var(--s1), var(--s2) 20%, var(--s3) 40%, var(--s4) 60%, var(--s5) 80%, var(--s6));

  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Consolas, "Liberation Mono", monospace;
  --measure: 44rem;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.62 var(--sans);
  -webkit-font-smoothing: antialiased;
}

::selection { background: rgba(111, 224, 207, 0.28); }

.wrap { width: min(var(--measure), 100% - 2.5rem); margin-inline: auto; }

/* The one decorative element on the page, and it is on-theme: a beam of light
   split into its wavelengths, pinned across the top of the viewport. */
.spectrum {
  position: fixed; top: 0; left: 0; right: 0; height: 3px;
  background: var(--spectrum); z-index: 50;
}

a {
  color: var(--link);
  text-decoration: none;
  border-bottom: 1px solid rgba(111, 224, 207, 0.35);
}
a:hover { border-bottom-color: var(--link); }
a:focus-visible { outline: 2px solid var(--link); outline-offset: 3px; }

code, .num {
  font-family: var(--mono);
  font-size: 0.88em;
  font-variant-numeric: tabular-nums;
}
code { color: var(--code); }

/* ------------------------------------------------------------------ masthead */
.masthead { border-bottom: 1px solid var(--rule); margin-top: 3px; }
.masthead .wrap {
  display: flex; flex-wrap: wrap; gap: 0.6rem 2rem;
  align-items: baseline; justify-content: space-between;
  padding: 1.3rem 0 1.15rem;
}
.who b { display: block; font-size: 1rem; letter-spacing: -0.01em; }
.who span {
  display: block; margin-top: 0.32rem;
  font: 500 0.66rem var(--mono);
  text-transform: uppercase; letter-spacing: 0.16em;
  color: var(--muted);
}
.masthead nav { display: flex; flex-wrap: wrap; gap: 1.3rem; }
.masthead nav a {
  font-size: 0.82rem; color: var(--ink-soft); border-bottom: none;
}
.masthead nav a:hover { color: var(--link); }

/* ---------------------------------------------------------------------- hero */
.hero { padding: 4rem 0 0; }

.eyebrow {
  margin: 0 0 1.6rem;
  font: 600 0.7rem var(--mono);
  text-transform: uppercase; letter-spacing: 0.2em;
  color: var(--link);
}

h1 {
  margin: 0;
  font-size: clamp(2.05rem, 5.6vw, 3.35rem);
  line-height: 1.04;
  letter-spacing: -0.035em;
  font-weight: 700;
}
.grad {
  background: var(--spectrum);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}

.lede {
  margin: 1.6rem 0 0;
  font-size: 1.1rem;
  line-height: 1.6;
  color: var(--ink-soft);
}
.lede strong { color: var(--ink); font-weight: 600; }

/* measurements, as a strip rather than four boxes */
.specs {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(8.5rem, 1fr));
  margin: 2.6rem 0 0;
  border-top: 1px solid var(--rule-strong);
  border-bottom: 1px solid var(--rule-strong);
}
.specs > span { padding: 1rem 1rem 1.05rem 0; }
.specs b {
  display: block;
  font-size: 1.5rem; line-height: 1.1; letter-spacing: -0.025em;
}
.specs i {
  display: block; margin-top: 0.38rem;
  font: 500 0.66rem var(--mono); font-style: normal;
  text-transform: uppercase; letter-spacing: 0.13em;
  color: var(--muted);
}

.actions { display: flex; flex-wrap: wrap; gap: 0.6rem; margin: 2.2rem 0 0; }

.btn {
  display: inline-block;
  padding: 0.7rem 1.15rem;
  border: 1px solid var(--rule-strong);
  background: transparent;
  color: var(--ink);
  font: 600 0.78rem var(--sans);
  text-transform: uppercase; letter-spacing: 0.1em;
  text-decoration: none;
}
.btn:hover { border-color: var(--ink); background: rgba(255, 255, 255, 0.05); color: var(--ink); }
.btn.primary {
  background: var(--spectrum);
  border-color: transparent;
  color: #141519;
  font-weight: 700;
}
.btn.primary:hover { filter: brightness(1.12); color: #141519; }

/* The hero frame. No border and no plate: the page behind it is the same
   colour as the render's backdrop, so the image dissolves and the stone
   appears to float on the page. */
.scene { margin: 3.6rem 0 0; }
.scene img {
  display: block;
  width: 100%; max-width: 1400px; height: auto;
  margin-inline: auto;
  mix-blend-mode: lighten;
}
figcaption {
  width: min(var(--measure), 100% - 2.5rem);
  margin: 1.1rem auto 0;
  font-size: 0.85rem; color: var(--muted);
}
figcaption b { color: var(--ink-soft); }

/* ------------------------------------------------------------------ sections */
section { border-top: 1px solid var(--rule); padding: 3.2rem 0; }

.sh { display: flex; gap: 0.85rem; align-items: baseline; margin-bottom: 1.15rem; }
.sn {
  font: 700 0.78rem var(--mono);
  background: var(--spectrum);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
h2 { margin: 0; font-size: 1.45rem; line-height: 1.2; letter-spacing: -0.025em; }

h3 { margin: 2rem 0 0.5rem; font-size: 1.02rem; letter-spacing: -0.01em; }

p { margin: 0 0 1.1rem; }
ul, ol { margin: 0 0 1.1rem; padding-left: 1.25rem; }
li { margin-bottom: 0.5rem; }
.muted { color: var(--muted); }

/* -------------------------------------------------------------------- tables */
.table-scroll { overflow-x: auto; margin: 1.4rem 0; }
table { border-collapse: collapse; width: 100%; font-size: 0.93rem; }
caption {
  caption-side: top; text-align: left;
  font-size: 0.83rem; color: var(--muted);
  padding-bottom: 0.7rem;
}
th {
  text-align: left; padding: 0.45rem 0.9rem 0.5rem 0;
  font: 600 0.66rem var(--mono); text-transform: uppercase; letter-spacing: 0.13em;
  color: var(--muted);
  border-bottom: 1px solid var(--rule-strong);
}
td { padding: 0.55rem 0.9rem 0.55rem 0; border-bottom: 1px solid var(--rule); }
td.n, th.n { text-align: right; padding-right: 1.6rem; font-family: var(--mono); font-variant-numeric: tabular-nums; }
tr.total td { border-bottom: none; font-weight: 700; }
tr.total td:first-child { font-weight: 400; color: var(--muted); }

/* ------------------------------------------------------- numbered items (bugs) */
.items { list-style: none; padding: 0; margin: 1.8rem 0 0; counter-reset: n; }
.items > li {
  position: relative;
  padding-left: 3.1rem;
  margin-bottom: 2.3rem;
  counter-increment: n;
}
.items > li:last-child { margin-bottom: 0.6rem; }
.items > li::before {
  content: counter(n);
  position: absolute; left: 0; top: -0.32rem;
  font: 700 1.85rem/1 var(--mono);
  background: var(--spectrum);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.items h3 { margin: 0 0 0.45rem; }
.items p:last-child { margin-bottom: 0; }
.lesson {
  display: block; margin-top: 0.7rem;
  color: var(--ink-soft); font-style: italic;
}

/* ------------------------------------------------------------------ callouts */
.callout {
  margin: 1.7rem 0 0;
  padding: 1.3rem 0;
  border-top: 1px solid var(--rule-strong);
  border-bottom: 1px solid var(--rule-strong);
}
.callout h3 { margin-top: 0; }
.callout ul { margin-bottom: 0; }

/* ----------------------------------------------------------------------- cta */
.cta .lede { margin-bottom: 1.6rem; }

footer {
  border-top: 1px solid var(--rule);
  padding: 1.9rem 0 3.2rem;
  color: var(--muted);
  font-size: 0.85rem;
}
footer p { margin: 0 0 0.4rem; }

@media (max-width: 34rem) {
  .specs { grid-template-columns: 1fr 1fr; }
  .items > li { padding-left: 2.5rem; }
}