/* Layout: a lamp box. One diamond, ray traced, in daylight or under a long-wave UV lamp, at GIA's five fluorescence
   strengths; the five side by side under the lamp; what GIA's 1997 study found; how it is tested. */
:root {
  --paper: #ffffff; --ink: #16161a; --ink-soft: #3d3d45; --muted: #6b6b75; --rule: #e4e2de; --mist: #f4f3f1;
  --ruby: #9b1b30; --gold: #b8892f; --uv: #5b7bff;
  --font-display: "Newsreader", Georgia, "Times New Roman", serif;
  --font-body: "Instrument Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-data: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
}

:root[data-theme="dark"] { --paper: #121216; --ink: #f1efe9; --ink-soft: #c9c6bf; --muted: #9a978f; --rule: #2c2c33; --mist: #1b1b21; --ruby: #e0566c; --gold: #e1b25a; --uv: #8ea5ff; color-scheme: dark; }
* { box-sizing: border-box; }
[hidden] { display: none !important; }
body { background: var(--paper); color: var(--ink); font-family: var(--font-body); font-size: 15px; line-height: 1.5; margin: 0; }
a { color: var(--ink); text-decoration-color: var(--ruby); text-underline-offset: 3px; }
.wrap { max-width: 1240px; margin: 0 auto; padding-inline: 16px; padding-block: 20px 48px; display: grid; gap: 24px; }
header.top { display: flex; flex-wrap: wrap; align-items: end; justify-content: space-between; gap: 12px; border-bottom: 1px solid var(--ink); padding-bottom: 14px; }
.eyebrow { font-size: 12px; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--ruby); display: inline-flex; align-items: center; gap: 10px; }
.eyebrow::before { content: ""; flex: none; width: 4px; height: 15px; background: var(--gold); clip-path: polygon(0 24%, 100% 0, 100% 76%, 0 100%); }
h1 { font-family: var(--font-display); font-weight: 500; font-size: clamp(30px, 4.6vw, 48px); line-height: 1.03; margin: 6px 0 0; }
h2.sec { font-family: var(--font-display); font-weight: 500; font-size: 28px; margin: 0; line-height: 1.1; }
.lede { max-width: 70ch; color: var(--ink-soft); margin: 6px 0 0; }
.prototype { font-size: 12px; color: var(--muted); border: 1px solid var(--rule); padding: 4px 10px; white-space: nowrap; }
.help { font-size: 12.5px; color: var(--muted); margin: 0; }
section.study { border-top: 1px solid var(--ink); padding-top: 18px; display: grid; gap: 14px; }
.seg { display: flex; flex-wrap: wrap; gap: 6px; }
.seg button { font: 600 13px var(--font-body); border: 1px solid var(--ink); background: var(--paper); color: var(--ink); padding: 6px 11px; cursor: pointer; }
.seg button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
button:focus-visible { outline: 2px solid var(--ruby); outline-offset: 2px; }
.field { display: grid; gap: 6px; font-size: 12px; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; color: var(--muted); }

.viewer { display: grid; gap: 18px; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); align-items: start; }
@media (max-width: 860px) { .viewer { grid-template-columns: 1fr; } }
.box { position: relative; aspect-ratio: 4 / 3; overflow: hidden; display: grid; place-items: center; transition: background .5s; }
.box.day { background: radial-gradient(circle at 50% 40%, #f6f5f1, #d9d7d0 80%); }
.box.uv { background: radial-gradient(circle at 50% 0%, #1d1440, #07060d 70%); }
.box .lamp { position: absolute; left: 50%; top: 0; width: 46%; height: 12px; transform: translateX(-50%); border-radius: 0 0 8px 8px; background: #2a2a33; transition: background .5s, box-shadow .5s; }
.box.uv .lamp { background: #6a4dff; box-shadow: 0 6px 40px 10px rgba(110, 70, 255, .45); }
.stone { position: relative; width: min(56%, 300px); aspect-ratio: 1; }
.stone img { position: absolute; inset: 0; width: 100%; height: 100%; transition: filter .5s; }
.box.uv .stone img { filter: brightness(var(--b, .3)) sepia(1) hue-rotate(198deg) saturate(var(--s, 1.2)); }
.glow { position: absolute; inset: 0; opacity: 0; transition: opacity .5s; mix-blend-mode: screen;
  background: radial-gradient(circle at 50% 50%, #8fa6ff 0%, #5a78ff 40%, #3a52ff 64%, rgba(40, 60, 255, .0) 74%);
  -webkit-mask-size: 100% 100%; mask-size: 100% 100%; }
.halo { position: absolute; inset: -14%; border-radius: 50%; opacity: 0; transition: opacity .5s; background: radial-gradient(circle, rgba(90, 120, 255, .55) 30%, rgba(90, 120, 255, 0) 68%); }
.haze { position: absolute; inset: 0; opacity: 0; transition: opacity .5s; border-radius: 50%; background: radial-gradient(circle, rgba(235, 238, 248, .55) 20%, rgba(235, 238, 248, .25) 50%, rgba(235, 238, 248, 0) 68%); }
.box .tag { position: absolute; left: 12px; bottom: 10px; font: 600 12px var(--font-body); letter-spacing: .06em; text-transform: uppercase; }
.box.day .tag { color: #3d3d45; } .box.uv .tag { color: #b9b4ff; }
.loading { position: absolute; font-size: 12px; color: #9a978f; }
.info { display: grid; gap: 14px; align-content: start; }
.info h3 { font-family: var(--font-display); font-weight: 500; font-size: 36px; margin: 0; line-height: 1; }
.info p { margin: 0; color: var(--ink-soft); }
.note { font-size: 13.5px; padding: 8px 10px; background: var(--mist); border-left: 3px solid var(--uv); margin: 0; }
.note.warn { border-left-color: var(--gold); }

.five { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 8px; }
@media (max-width: 640px) { .five { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
.five .box { aspect-ratio: 1; cursor: pointer; border: 0; padding: 0; }
.five .box .stone { width: 72%; }
.five .box .tag { left: 0; right: 0; text-align: center; bottom: 6px; font-size: 12px; }
.five .box .lamp { display: none; }
.find { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }
.find div { border: 1px solid var(--rule); padding: 12px 14px; display: grid; gap: 4px; align-content: start; }
.find b { font-family: var(--font-display); font-weight: 500; font-size: 20px; }
.find span { font-size: 12px; color: var(--muted); letter-spacing: .04em; text-transform: uppercase; }
.find p { margin: 0; font-size: 14px; color: var(--ink-soft); }
.sources { display: grid; gap: 6px; font-size: 13px; color: var(--ink-soft); max-width: 92ch; }
.sources p { margin: 0; }
/* jewelloop.net: one column that never grows wider than the screen */
.wrap { grid-template-columns: minmax(0, 1fr); }
.jl-table-scroll { overflow-x: auto; max-width: 100%; }
/* shown once the page's script has run (static/visual/ready.js): no jump while loading */
html:not(.jl-ready) .wrap { visibility: hidden; }

/* On jewelloop.net the page around it shows the title and the introduction. */
header.top { display: none !important; }