/* bdrworks.org — Apple-inspired design system
   Change --radius to adjust how rounded every card/tile is. */

:root {
  --bg: #ffffff;
  --bg-alt: #f5f5f7;
  --bg-tile: #ffffff;
  --bg-tile-alt: #fbfbfd;
  --text: #1d1d1f;
  --text-2: #424245;
  --text-3: #6e6e73;
  --line: #d2d2d7;
  --line-soft: #e8e8ed;
  --link: #0066cc;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --green: #1d8a3a;
  --orange: #b64400;
  --nav-bg: rgba(250, 250, 252, 0.8);
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 10px 40px rgba(0, 0, 0, 0.12);
  --radius: 18px;
  --radius-lg: 28px;
  --radius-sm: 12px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Inter", "Helvetica Neue", "Segoe UI", Arial, sans-serif;
  --mono: "SF Mono", ui-monospace, "JetBrains Mono", Menlo, Consolas, monospace;
  --max: 1080px;
  --chart-1: #0071e3;
  --chart-2: #e8590c;
  --chart-3: #1d8a3a;
  --chart-4: #8944ab;
  --chart-grid: #e8e8ed;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #000000;
    --bg-alt: #101012;
    --bg-tile: #1c1c1e;
    --bg-tile-alt: #161617;
    --text: #f5f5f7;
    --text-2: #d2d2d7;
    --text-3: #98989d;
    --line: #424245;
    --line-soft: #2c2c2e;
    --link: #2997ff;
    --accent: #0a84ff;
    --accent-hover: #409cff;
    --green: #30d158;
    --orange: #ff9f0a;
    --nav-bg: rgba(22, 22, 23, 0.8);
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
    --shadow-hover: 0 10px 40px rgba(0, 0, 0, 0.6);
    --chart-1: #2997ff;
    --chart-2: #ff9f0a;
    --chart-3: #30d158;
    --chart-4: #bf5af2;
    --chart-grid: #2c2c2e;
  }
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.47;
  letter-spacing: -0.022em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { width: 100%; max-width: var(--max); margin: 0 auto; padding: 0 22px; }
.container-narrow { max-width: 760px; margin: 0 auto; padding: 0 22px; }

/* ---------- Navigation ---------- */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--line-soft);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 48px; }
.brand { color: var(--text); font-weight: 600; font-size: 17px; letter-spacing: -0.02em; }
.brand span { color: var(--text-3); font-weight: 400; }
.brand:hover { text-decoration: none; }
.nav-links { display: flex; gap: 28px; list-style: none; align-items: center; }
.nav-links a { color: var(--text-2); font-size: 13px; letter-spacing: -0.01em; }
.nav-links a:hover, .nav-links a.active { color: var(--text); text-decoration: none; }
.nav-links a.active { font-weight: 600; }
.nav-toggle { display: none; background: none; border: 0; color: var(--text); font-size: 22px; cursor: pointer; width: 40px; height: 40px; }

@media (max-width: 720px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none; position: absolute; top: 48px; left: 0; right: 0;
    flex-direction: column; gap: 0; align-items: stretch;
    background: var(--bg); border-bottom: 1px solid var(--line-soft); padding: 8px 22px 20px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { display: block; font-size: 17px; padding: 12px 0; border-bottom: 1px solid var(--line-soft); }
}

/* ---------- Sub navigation (project pages) ---------- */
.subnav {
  position: sticky; top: 48px; z-index: 90;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--line-soft);
}
.subnav-inner { display: flex; align-items: center; justify-content: space-between; height: 52px; gap: 16px; }
.subnav-title { font-size: 21px; font-weight: 600; letter-spacing: 0.01em; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.subnav-links { display: flex; gap: 22px; font-size: 12px; align-items: center; }
.subnav-links a { color: var(--text-2); }
@media (max-width: 720px) { .subnav-links a:not(.pill) { display: none; } .subnav-title { font-size: 17px; } }

/* ---------- Typography ---------- */
.eyebrow { font-size: 17px; font-weight: 600; color: var(--orange); letter-spacing: -0.01em; margin-bottom: 6px; }
.eyebrow.blue { color: var(--accent); }
.eyebrow.green { color: var(--green); }
.headline { font-size: clamp(40px, 7vw, 80px); line-height: 1.05; font-weight: 700; letter-spacing: -0.015em; }
.h1 { font-size: clamp(36px, 5.5vw, 56px); line-height: 1.07; font-weight: 700; letter-spacing: -0.005em; }
.h2 { font-size: clamp(28px, 4vw, 40px); line-height: 1.1; font-weight: 700; letter-spacing: 0; }
.h3 { font-size: clamp(22px, 2.6vw, 28px); line-height: 1.14; font-weight: 700; letter-spacing: 0.004em; }
.lead { font-size: clamp(19px, 2.2vw, 24px); line-height: 1.33; color: var(--text-2); font-weight: 400; letter-spacing: 0.009em; }
.muted { color: var(--text-3); }
.center { text-align: center; }

/* ---------- Buttons & links ---------- */
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  font-size: 17px; padding: 11px 22px; border-radius: 980px; border: 0; cursor: pointer;
  font-family: inherit; letter-spacing: -0.01em; transition: background .2s;
}
.btn:hover { background: var(--accent-hover); text-decoration: none; }
.btn.ghost { background: transparent; color: var(--link); box-shadow: inset 0 0 0 1px var(--link); }
.btn.ghost:hover { background: var(--link); color: #fff; }
.pill { background: var(--accent); color: #fff !important; font-size: 12px; padding: 5px 12px; border-radius: 980px; }
.pill:hover { text-decoration: none; background: var(--accent-hover); }
.more::after { content: " \203A"; }
.cta-row { display: flex; gap: 20px; justify-content: center; align-items: center; flex-wrap: wrap; margin-top: 26px; }

/* ---------- Sections ---------- */
section { padding: 90px 0; }
.section-alt { background: var(--bg-alt); }
.section-head { text-align: center; max-width: 760px; margin: 0 auto 48px; }
.section-head .lead { margin-top: 14px; }

/* ---------- Hero ---------- */
.hero { padding: 110px 0 60px; text-align: center; overflow: hidden; }
.hero .lead { max-width: 680px; margin: 18px auto 0; }
.hero-strip {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 70px;
}
.hero-strip figure { border-radius: var(--radius); overflow: hidden; aspect-ratio: 3 / 4; background: var(--bg-alt); }
.hero-strip figure:nth-child(even) { transform: translateY(36px); }
.hero-strip img { width: 100%; height: 100%; object-fit: cover; }
@media (max-width: 720px) { .hero-strip { grid-template-columns: repeat(2, 1fr); } }

/* ---------- Segmented control ---------- */
.segmented {
  display: inline-flex; background: var(--line-soft); border-radius: 980px; padding: 3px; margin: 0 auto 40px;
}
.segmented button {
  border: 0; background: transparent; font: inherit; font-size: 14px; color: var(--text-2);
  padding: 8px 20px; border-radius: 980px; cursor: pointer;
}
.segmented button.active { background: var(--bg-tile); color: var(--text); box-shadow: 0 1px 4px rgba(0,0,0,.12); font-weight: 600; }
.seg-wrap { text-align: center; }

/* ---------- Project tiles ---------- */
.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 900px) { .grid-3 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px) { .grid-2, .grid-3 { grid-template-columns: 1fr; } }

.tile {
  background: var(--bg-tile); border-radius: var(--radius); overflow: hidden;
  display: flex; flex-direction: column; color: var(--text);
  box-shadow: var(--shadow); transition: transform .35s cubic-bezier(.2,.8,.2,1), box-shadow .35s;
}
a.tile:hover { text-decoration: none; transform: translateY(-4px) scale(1.005); box-shadow: var(--shadow-hover); }
.tile-media { aspect-ratio: 4 / 3; overflow: hidden; background: var(--bg-alt); }
.tile-media img { width: 100%; height: 100%; object-fit: cover; transition: transform .6s cubic-bezier(.2,.8,.2,1); }
a.tile:hover .tile-media img { transform: scale(1.04); }
.tile-body { padding: 24px 26px 28px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.tile-kicker { font-size: 12px; font-weight: 600; color: var(--orange); text-transform: uppercase; letter-spacing: 0.04em; }
.tile h3 { font-size: 24px; line-height: 1.17; font-weight: 700; letter-spacing: 0.005em; }
.tile p { font-size: 15px; color: var(--text-2); line-height: 1.45; }
.tile .more { margin-top: auto; padding-top: 10px; font-size: 15px; color: var(--link); }
.tile.feature { grid-column: 1 / -1; flex-direction: row; }
.tile.feature .tile-media { flex: 1.1; aspect-ratio: auto; height: 460px; }
.tile.feature .more { margin-top: 18px; }
.tile.feature .tile-body { flex: 1; padding: 48px; justify-content: center; }
.tile.feature h3 { font-size: clamp(28px, 3.4vw, 40px); }
.tile.feature p { font-size: 17px; }
@media (max-width: 760px) {
  .tile.feature { flex-direction: column; }
  .tile.feature .tile-media { min-height: 0; aspect-ratio: 4 / 3; }
  .tile.feature .tile-body { padding: 26px; }
}
.tile.plain .tile-body { padding: 30px; }
.tag-row { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 4px; }
.tag { font-size: 12px; color: var(--text-2); background: var(--bg-alt); padding: 3px 10px; border-radius: 980px; }
.status { display: inline-flex; align-items: center; gap: 6px; font-size: 12px; color: var(--text-3); }
.status::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--green); }
.status.ongoing::before { background: var(--orange); }

/* ---------- Stat band ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.stat { background: var(--bg-tile); border-radius: var(--radius); padding: 28px 24px; box-shadow: var(--shadow); }
.stat .num { font-size: clamp(32px, 4vw, 48px); font-weight: 700; letter-spacing: -0.01em; line-height: 1.05; }
.stat .num small { font-size: 0.5em; font-weight: 600; }
.stat .lbl { font-size: 14px; color: var(--text-3); margin-top: 8px; line-height: 1.35; }
@media (max-width: 760px) { .stats { grid-template-columns: repeat(2, 1fr); } }

/* ---------- Project page ---------- */
.p-hero { padding: 80px 0 40px; text-align: center; }
.p-hero .lead { max-width: 720px; margin: 18px auto 0; }
.p-hero-media { margin-top: 56px; border-radius: var(--radius-lg); overflow: hidden; background: var(--bg-alt); }
.p-hero-media img { width: 100%; max-height: 640px; object-fit: cover; }

.prose { font-size: 19px; line-height: 1.58; color: var(--text-2); letter-spacing: 0.004em; }
.prose p + p { margin-top: 1.1em; }
.prose strong { color: var(--text); font-weight: 600; }
.prose h2 { font-size: clamp(28px, 3.6vw, 40px); line-height: 1.1; color: var(--text); margin: 70px 0 20px; letter-spacing: 0; }
.prose h3 { font-size: 24px; color: var(--text); margin: 44px 0 12px; }
.prose ul { margin: 1em 0 1em 1.2em; }
.prose li + li { margin-top: .4em; }

.figure { margin: 44px 0; }
.figure .frame { border-radius: var(--radius); overflow: hidden; background: var(--bg-alt); cursor: zoom-in; }
.figure .frame.contain { background: #fff; padding: 20px; }
.figure img { width: 100%; height: auto; }
.figure figcaption { font-size: 14px; color: var(--text-3); margin-top: 12px; line-height: 1.45; }
.figure figcaption b { color: var(--text-2); font-weight: 600; }
.fig-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; margin: 44px 0; }
.fig-grid.three { grid-template-columns: repeat(3, 1fr); }
.fig-grid .figure { margin: 0; }
.fig-grid .frame { aspect-ratio: 3 / 4; }
.fig-grid .frame img { height: 100%; object-fit: cover; }
.fig-grid.land .frame { aspect-ratio: 4 / 3; }
@media (max-width: 640px) { .fig-grid, .fig-grid.three { grid-template-columns: 1fr; } }
.figure.portrait { max-width: 520px; margin-left: auto; margin-right: auto; }

.spec {
  background: var(--bg-alt); border-radius: var(--radius); padding: 8px 28px; margin: 40px 0;
}
.spec-row { display: grid; grid-template-columns: 200px 1fr; gap: 20px; padding: 16px 0; border-bottom: 1px solid var(--line-soft); font-size: 16px; }
.spec-row:last-child { border-bottom: 0; }
.spec-row dt { color: var(--text-3); }
.spec-row dd { color: var(--text); font-weight: 500; }
@media (max-width: 560px) { .spec-row { grid-template-columns: 1fr; gap: 2px; } }

.callout { background: var(--bg-alt); border-radius: var(--radius); padding: 26px 28px; margin: 36px 0; font-size: 17px; color: var(--text-2); }
.callout .eyebrow { font-size: 14px; margin-bottom: 6px; }

.next-card { display: flex; justify-content: space-between; align-items: center; gap: 20px; background: var(--bg-tile); border-radius: var(--radius); padding: 30px; box-shadow: var(--shadow); color: var(--text); }
.next-card:hover { text-decoration: none; box-shadow: var(--shadow-hover); }
.next-card .h3 { margin-top: 4px; }
.next-card .arrow { font-size: 28px; color: var(--link); }

/* ---------- Technical report layout ---------- */
.report { display: grid; grid-template-columns: 220px 1fr; gap: 60px; align-items: start; }
.toc { position: sticky; top: 124px; font-size: 13px; }
.toc-title { font-size: 12px; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .06em; margin-bottom: 12px; }
.toc ol { list-style: none; border-left: 1px solid var(--line); }
.toc a { display: block; color: var(--text-3); padding: 6px 0 6px 14px; margin-left: -1px; border-left: 2px solid transparent; line-height: 1.3; }
.toc a:hover { color: var(--text); text-decoration: none; }
.toc a.active { color: var(--text); border-left-color: var(--accent); font-weight: 600; }
.report .prose h2:first-child { margin-top: 0; }
.report .prose h2 .sec-no { color: var(--text-3); font-weight: 600; margin-right: 10px; }
@media (max-width: 960px) { .report { grid-template-columns: 1fr; } .toc { display: none; } }

.abstract { background: var(--bg-alt); border-radius: var(--radius); padding: 34px 36px; font-size: 18px; line-height: 1.6; color: var(--text-2); }
.abstract .toc-title { margin-bottom: 10px; }
.doc-meta { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px 28px; margin-top: 26px; font-size: 14px; color: var(--text-3); }
.doc-meta b { color: var(--text); font-weight: 600; }

.equation {
  font-family: "Times New Roman", "STIX Two Math", serif; font-style: italic; font-size: 22px; color: var(--text);
  background: var(--bg-alt); border-radius: var(--radius-sm); padding: 20px 24px; margin: 22px 0; text-align: center; overflow-x: auto; letter-spacing: 0;
}
.equation .lbl { font-family: var(--font); font-style: normal; font-size: 13px; color: var(--text-3); display: block; margin-top: 8px; }
.equation sub, .equation sup { font-size: 0.65em; }

table.data { width: 100%; border-collapse: collapse; font-size: 15px; margin: 8px 0; font-variant-numeric: tabular-nums; }
table.data th { text-align: left; font-weight: 600; color: var(--text-3); font-size: 13px; padding: 10px 12px; border-bottom: 1px solid var(--line); }
table.data td { padding: 11px 12px; border-bottom: 1px solid var(--line-soft); color: var(--text); }
table.data tr:last-child td { border-bottom: 0; }
table.data td.num, table.data th.num { text-align: right; }
table.data tfoot td { font-weight: 700; border-top: 1px solid var(--line); }
.table-card { background: var(--bg-tile); border-radius: var(--radius); box-shadow: var(--shadow); padding: 14px 16px; margin: 36px 0 10px; overflow-x: auto; }
.table-cap { font-size: 14px; color: var(--text-3); margin-bottom: 36px; }

pre.code {
  font-family: var(--mono); font-size: 13px; line-height: 1.55; background: #1d1d1f; color: #f5f5f7;
  border-radius: var(--radius); padding: 24px; overflow-x: auto; margin: 24px 0; letter-spacing: 0;
}
pre.code .c { color: #8e8e93; } pre.code .k { color: #ff7ab2; } pre.code .s { color: #ff8170; } pre.code .n { color: #d9c97c; }
details.code-toggle summary { cursor: pointer; color: var(--link); font-size: 17px; list-style: none; }
details.code-toggle summary::-webkit-details-marker { display: none; }
details.code-toggle summary::after { content: " \203A"; }
details.code-toggle[open] summary::after { content: " \2039"; }

.refs { font-size: 14px; color: var(--text-3); line-height: 1.55; }
.refs li { margin: 0 0 10px 1.1em; }
.refs a { word-break: break-all; }

/* ---------- Charts ---------- */
.chart-card { background: var(--bg-tile); border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px 22px 14px; margin: 36px 0 10px; }
.chart-card .chart-title { font-size: 15px; font-weight: 600; color: var(--text); margin-bottom: 2px; }
.chart-card .chart-sub { font-size: 13px; color: var(--text-3); margin-bottom: 10px; }
.chart { width: 100%; position: relative; }
.chart svg { width: 100%; height: auto; display: block; overflow: visible; }
.chart svg text { fill: var(--text-3); font-family: var(--font); font-size: 11px; letter-spacing: 0; }
.chart svg .grid line { stroke: var(--chart-grid); }
.chart svg .axis-title { fill: var(--text-2); font-size: 12px; }
.chart-legend { display: flex; gap: 18px; font-size: 13px; color: var(--text-2); margin: 6px 0 4px; flex-wrap: wrap; }
.chart-legend span::before { content: ""; display: inline-block; width: 14px; height: 3px; border-radius: 2px; background: var(--c); vertical-align: middle; margin-right: 7px; }
.chart-tip {
  position: absolute; pointer-events: none; background: var(--bg-tile); color: var(--text); border: 1px solid var(--line-soft);
  box-shadow: var(--shadow-hover); border-radius: 10px; padding: 6px 10px; font-size: 12px; white-space: nowrap; opacity: 0; transition: opacity .12s;
}

/* ---------- Calculations ---------- */
.calc-nav { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; margin-bottom: 40px; }
.calc-nav button {
  border: 0; font: inherit; font-size: 14px; padding: 9px 18px; border-radius: 980px; cursor: pointer;
  background: var(--bg-tile); color: var(--text-2); box-shadow: inset 0 0 0 1px var(--line);
}
.calc-nav button.active { background: var(--text); color: var(--bg); box-shadow: none; font-weight: 600; }
.calc-panel { display: none; }
.calc-panel.active { display: block; animation: fade .35s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.calc-card { background: var(--bg-tile); border-radius: var(--radius-lg); box-shadow: var(--shadow); padding: 40px; }
@media (max-width: 640px) { .calc-card { padding: 24px 20px; } }
.calc-card .h3 { margin-bottom: 6px; }
.calc-card .desc { color: var(--text-3); font-size: 15px; margin-bottom: 28px; max-width: 680px; }
.inputs { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 16px; margin-bottom: 30px; }
.field label { display: block; font-size: 12px; font-weight: 600; color: var(--text-3); margin-bottom: 6px; letter-spacing: 0; }
.field input, .field select {
  width: 100%; font: inherit; font-size: 17px; color: var(--text); background: var(--bg-alt);
  border: 1px solid transparent; border-radius: var(--radius-sm); padding: 12px 14px; outline: none; transition: border-color .2s, box-shadow .2s;
  -webkit-appearance: none; appearance: none;
}
.field select { background-image: linear-gradient(45deg, transparent 50%, var(--text-3) 50%), linear-gradient(135deg, var(--text-3) 50%, transparent 50%); background-position: calc(100% - 20px) 55%, calc(100% - 15px) 55%; background-size: 5px 5px; background-repeat: no-repeat; padding-right: 36px; }
.field input:focus, .field select:focus { border-color: var(--accent); box-shadow: 0 0 0 4px rgba(0,113,227,.15); }
.results { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 12px; }
.result { background: var(--bg-alt); border-radius: var(--radius-sm); padding: 16px 18px; cursor: pointer; transition: background .2s; position: relative; }
.result:hover { background: var(--line-soft); }
.result .r-lbl { font-size: 12px; color: var(--text-3); }
.result .r-val { font-size: 24px; font-weight: 600; margin-top: 2px; font-variant-numeric: tabular-nums; letter-spacing: -0.01em; overflow-wrap: anywhere; word-break: normal; }
.result .r-unit { font-size: 13px; color: var(--text-3); }
.result.primary { background: var(--accent); }
.result.primary .r-lbl, .result.primary .r-unit, .result.primary .r-val { color: #fff; }
.result .copied { position: absolute; top: 10px; right: 12px; font-size: 11px; color: var(--green); opacity: 0; transition: opacity .2s; }
.result.primary .copied { color: #fff; }
.result.flash .copied { opacity: 1; }
.note { font-size: 13px; color: var(--text-3); margin-top: 22px; line-height: 1.5; }
.formula-box { font-family: var(--mono); font-size: 13px; color: var(--text-2); background: var(--bg-alt); border-radius: var(--radius-sm); padding: 14px 16px; margin-top: 20px; overflow-x: auto; letter-spacing: 0; }
.warn { color: var(--orange); font-size: 13px; margin-top: 10px; min-height: 1em; }

/* ---------- Lightbox ---------- */
.lightbox { position: fixed; inset: 0; background: rgba(0,0,0,.9); z-index: 1000; display: none; align-items: center; justify-content: center; padding: 40px; cursor: zoom-out; }
.lightbox.open { display: flex; animation: fade .25s ease; }
.lightbox img { max-width: 100%; max-height: 100%; border-radius: 10px; object-fit: contain; }
.lightbox .lb-cap { position: absolute; bottom: 16px; left: 0; right: 0; text-align: center; color: #d2d2d7; font-size: 14px; padding: 0 20px; }

/* ---------- Reveal on scroll ---------- */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .8s cubic-bezier(.2,.8,.2,1), transform .8s cubic-bezier(.2,.8,.2,1); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } html { scroll-behavior: auto; } }

/* ---------- Footer ---------- */
footer { background: var(--bg-alt); font-size: 12px; color: var(--text-3); padding: 30px 0 40px; }
footer .foot-inner { display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; border-top: 1px solid var(--line); padding-top: 18px; }
footer a { color: var(--text-2); }
footer .foot-links { display: flex; gap: 20px; }

/* Plain prose: no bold inside running text */
.prose strong, .prose b { font-weight: inherit; color: inherit; }
.stats.three { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 760px) { .stats.three { grid-template-columns: 1fr; } }
.calc-group-title { font-size: 12px; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .06em; margin: 34px 0 12px; }
.sweep { margin-top: 26px; max-width: 700px; }

/* Calculator groups & theory */
.calc-nav { display: grid; grid-template-columns: repeat(4, auto); justify-content: center; gap: 18px 34px; margin-bottom: 44px; }
.calc-group-title { margin: 0 0 10px; text-align: left; }
.calc-group-btns { display: flex; flex-direction: column; gap: 8px; align-items: stretch; }
.calc-group-btns button { text-align: left; }
@media (max-width: 900px) { .calc-nav { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .calc-nav { grid-template-columns: 1fr; } .calc-group-btns { flex-direction: row; flex-wrap: wrap; } }
.theory { max-width: 760px; margin: 50px auto 0; font-size: 17px; line-height: 1.6; color: var(--text-2); }
.theory .h3 { color: var(--text); margin-bottom: 16px; }
.theory p + p, .theory .eq + p { margin-top: 14px; }
.theory .eq { font-family: "Times New Roman", "STIX Two Math", serif; font-style: italic; font-size: 19px; color: var(--text); background: var(--bg-alt); border-radius: var(--radius-sm); padding: 16px 20px; margin: 16px 0; text-align: center; overflow-x: auto; letter-spacing: 0; }
.theory .eq sub, .theory .eq sup { font-size: .68em; }

/* Contact */
.contact { margin: 34px auto 0; padding: 26px; background: var(--bg-alt); border-radius: var(--radius); max-width: 420px; }
.contact-mail { font-size: 22px; font-weight: 600; letter-spacing: -0.01em; }

/* Stack game */
:root { --grid-empty: #ececf0; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) { --grid-empty: #202023; } }
.game { display: flex; gap: 28px; justify-content: center; align-items: flex-start; }
.board-wrap { position: relative; flex: 0 1 340px; background: var(--bg-tile); border-radius: var(--radius-lg); box-shadow: var(--shadow); padding: 14px; }
.board-wrap canvas { display: block; margin: 0 auto; touch-action: none; }
.overlay { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; background: color-mix(in srgb, var(--bg-tile) 72%, transparent); backdrop-filter: blur(6px); -webkit-backdrop-filter: blur(6px); border-radius: var(--radius-lg); }
.overlay[hidden] { display: none; }
.ov-card { text-align: center; padding: 24px; max-width: 260px; }
.ov-card p { color: var(--text-2); font-size: 15px; margin: 8px 0 18px; }
.game-side { display: flex; flex-direction: column; gap: 12px; width: 200px; }
.side-card { padding: 16px 18px; }
.side-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.keys { font-size: 13px; color: var(--text-3); line-height: 2; padding: 6px 4px; }
kbd { font-family: var(--font); font-size: 12px; background: var(--bg-tile); border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 6px; padding: 1px 7px; margin-right: 4px; color: var(--text); }
.touch { display: none; grid-template-columns: repeat(3, 1fr); gap: 10px; max-width: 360px; margin: 18px auto 0; }
.touch button { font: inherit; font-size: 22px; height: 56px; border: 0; border-radius: var(--radius-sm); background: var(--bg-tile); color: var(--text); box-shadow: var(--shadow); touch-action: manipulation; }
@media (max-width: 720px) {
  .game { flex-direction: column; align-items: center; }
  .game-side { width: 100%; max-width: 368px; flex-direction: row; flex-wrap: wrap; }
  .game-side > * { flex: 1 1 40%; } .keys { display: none; }
  .touch { display: grid; }
}
@media (hover: none) { .touch { display: grid; } }

/* Calculator nav: 6 groups */
.calc-nav { grid-template-columns: repeat(3, minmax(0, 220px)); }
@media (max-width: 900px) { .calc-nav { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .calc-nav { grid-template-columns: 1fr; } }

/* Calculator search */
.calc-search-wrap { max-width: 560px; margin: 0 auto 34px; text-align: center; }
#calc-search { width: 100%; font: inherit; font-size: 17px; color: var(--text); background: var(--bg-alt); border: 1px solid transparent; border-radius: 980px; padding: 13px 22px; outline: none; -webkit-appearance: none; appearance: none; }
#calc-search:focus { border-color: var(--accent); box-shadow: 0 0 0 4px rgba(0,113,227,.15); }
.calc-count { font-size: 13px; color: var(--text-3); margin-top: 10px; }
.calc-panel { scroll-margin-top: 64px; }

/* ---------- O-ring calculator ---------- */
.or-top { display: flex; justify-content: center; margin-bottom: 18px; }
.or-top .segmented { margin: 0; }
.or-top .segmented button { font-size: 16px; padding: 10px 24px; }
.or-toggles { display: flex; flex-wrap: wrap; gap: 14px 26px; justify-content: center; margin-bottom: 26px; }
.or-toggles .segmented { margin: 0; }
.or-tlbl { font-size: 11px; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .06em; margin: 0 0 6px 4px; }
.or-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 20px; align-items: start; }
@media (max-width: 1000px) { .or-grid { grid-template-columns: 1fr; } }
.or-card { padding: 28px; }
.or-head { margin-bottom: 14px; }
.or-scroll { overflow-x: auto; }
.or-table td, .or-table th { white-space: nowrap; }
.or-table input, .or-table select, #or-notes { font: inherit; font-size: 14px; color: var(--text); background: var(--bg-alt); border: 1px solid transparent; border-radius: 8px; padding: 7px 9px; width: 100%; min-width: 86px; outline: none; -webkit-appearance: none; appearance: none; }
.or-table select { min-width: 150px; background-image: linear-gradient(45deg, transparent 50%, var(--text-3) 50%), linear-gradient(135deg, var(--text-3) 50%, transparent 50%); background-position: calc(100% - 14px) 55%, calc(100% - 10px) 55%; background-size: 4px 4px; background-repeat: no-repeat; padding-right: 24px; }
.or-table input:focus, .or-table select:focus, #or-notes:focus { border-color: var(--accent); }
.or-table input::placeholder { color: var(--text-3); }
.or-sym { color: var(--text-3); font-style: italic; }
.or-out { font-variant-numeric: tabular-nums; color: var(--text-2); }
.or-res td:not(:first-child) { font-variant-numeric: tabular-nums; }
.or-rec { color: var(--text-3); font-size: 13px; }
.or-ok { font-size: 12px; font-weight: 600; color: #fff; background: var(--green); border-radius: 980px; padding: 2px 9px; }
.or-bad { font-size: 12px; font-weight: 600; color: #fff; background: var(--orange); border-radius: 980px; padding: 2px 9px; }
.or-warn { margin: 18px 0 0 1.1em; font-size: 15px; color: var(--orange); line-height: 1.5; }
.or-warn li + li { margin-top: 6px; }
.or-warn .or-good { color: var(--green); list-style: none; margin-left: -1.1em; }
.or-warn .or-inf { color: var(--text-2); }
.or-hb { margin: 14px 0 0 1.1em; font-size: 15px; color: var(--text-2); line-height: 1.55; }
.or-hb li + li { margin-top: 6px; }
.or-chk { font-size: 14px; }
.or-chk td, .or-chk th { white-space: normal; }
.or-actions { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-top: 18px; }
.or-actions .btn { font-size: 15px; padding: 9px 18px; }
.or-svg { width: 100%; height: auto; }
.or-svg text { fill: var(--text-3); font-size: 12px; font-family: var(--font); }
.or-sizes tbody tr:hover { background: var(--bg-alt); }
.or-use { font: inherit; font-size: 13px; border: 0; background: var(--accent); color: #fff; border-radius: 980px; padding: 4px 12px; cursor: pointer; }
#or-notes { width: 100%; min-height: 90px; resize: vertical; margin-top: 10px; }
@media print { .nav, footer, .or-actions, .or-filter, .or-sizes, #or-notes, .theory { display: none !important; } .calc-card { box-shadow: none; } }
.or-page .container { max-width: 1280px; }
.or-dimcard { display: grid; grid-template-columns: minmax(0, 1fr) 340px; gap: 28px; align-items: start; }
@media (max-width: 1100px) { .or-dimcard { grid-template-columns: 1fr; } .or-schemwrap { max-width: 460px; margin: 0 auto; } }
.or-schem { width: 100%; height: auto; }
.or-schem .metal { fill: url(#hch); stroke: var(--text-3); stroke-width: 1.2; }
.or-schem .hl { stroke: var(--line); stroke-width: 2; }
.or-schem .rod { fill: var(--bg-alt); stroke: var(--text-3); stroke-width: 1.2; }
.or-schem .oring { fill: #1aa6c9; stroke: #0b6c85; stroke-width: 1.5; }
.or-schem .ringband { fill: #9fdcec; stroke: #0b6c85; stroke-width: 1.2; }
.or-schem .cl { stroke: var(--text-3); stroke-width: 1; stroke-dasharray: 10 4 2 4; }
.or-schem .ext { stroke: var(--text-3); stroke-width: .8; }
.or-schem .dl { stroke: var(--text-2); stroke-width: 1.1; fill: none; }
.or-schem .ah { fill: var(--text-2); }
.or-schem text { fill: var(--text); font-size: 15px; font-style: italic; font-family: "Times New Roman", serif; }
.or-schem text.small { font-size: 12px; font-style: normal; font-family: var(--font); fill: var(--text-3); }
.or-schem .sb { font-size: 11px; }
.or-schem .dm.on .dl, .or-schem .dm.on .ext { stroke: var(--accent); stroke-width: 2; }
.or-schem .dm.on text { fill: var(--accent); font-weight: 700; }
.or-schem .dm.on .ah { fill: var(--accent); }
#or-rows tr:hover td { background: var(--bg-alt); }

.or-dimcard .or-table td, .or-dimcard .or-table th { padding-left: 6px; padding-right: 6px; }
.or-dimcard .or-table input { min-width: 70px; }
.or-dimcard .or-table select { min-width: 136px; }
.or-dimcard { grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); }
.or-dimcard .or-table input { max-width: 160px; }
.or-drawhead { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 8px; }
.or-play { padding: 6px 14px; font-size: 14px; }
.or-live .metal { fill: url(#hch2); stroke: var(--text-3); stroke-width: 1.2; }
.or-live .hl { stroke: var(--line); stroke-width: 2; }
.or-live .ring { fill: #1aa6c9; stroke: #0b6c85; stroke-width: 1.4; }
.or-live .ring.bad { stroke: #e0443e; stroke-width: 2; }
.or-live .bu { fill: #f2a93b; stroke: #a8680f; stroke-width: 1.2; }
.or-live .dl { stroke: var(--text-2); stroke-width: 1; fill: none; }
.or-live .ext { stroke: var(--text-3); stroke-width: .7; }
.or-live .ah { fill: var(--text-2); }
.or-live .pa { fill: #e0443e; }
.or-live .parr { stroke: #e0443e; stroke-width: 1.6; }
.or-live .ptxt { fill: #e0443e; font-weight: 600; }
.or-live .plab { fill: var(--text-2); font-size: 12px; font-weight: 600; }
.or-live .stat { font-size: 12.5px; font-weight: 600; }
.or-live .stat.ok { fill: #1f9d55; } .or-live .stat.bad { fill: #e0443e; }
.or-legend { display: flex; gap: 16px; font-size: 13px; color: var(--text-2); margin-top: 6px; flex-wrap: wrap; }
.or-legend i { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; }
.lg-ring { background: #1aa6c9; } .lg-bu { background: #f2a93b; } .lg-metal { background: repeating-linear-gradient(45deg, var(--line) 0 2px, transparent 2px 5px); border: 1px solid var(--text-3); }
.or-schemwrap { max-width: 440px; justify-self: center; width: 100%; }
.or-live .stat.warn { fill: #c77700; } .or-live .dl.bad { stroke: #e0443e; stroke-width: 1.6; }
.or-msg { font-size: 14px; font-weight: 600; margin: 4px 0 0; min-height: 20px; }
.or-msg.ok { color: #17803f; } .or-msg.warn { color: #9a5b00; } .or-msg.bad { color: #c62f2a; }
/* ---------- Handbook ---------- */
.hb-media img { object-fit: contain; background: #fff; padding: 10px; }
.hb .prose ul { margin: 0 0 24px 1.2em; } .hb .prose ul li { margin-bottom: 8px; }
.equation.tex { font-style: normal; overflow-x: auto; overflow-y: hidden; }
.equation.tex .katex-display { margin: 0; }
.nw { white-space: nowrap; }
.codebox { margin: 30px 0 44px; }
.cb-tabs { margin-bottom: 10px; }
.cb-bar { display: flex; justify-content: space-between; align-items: center; background: #2a2a2e; color: #c7c7cc; font: 13px var(--mono); padding: 8px 14px; border-radius: var(--radius-sm) var(--radius-sm) 0 0; }
.cb-actions { display: flex; gap: 14px; align-items: center; }
.cb-copy, .cb-dl { font: 13px var(--font); color: #8fc1ff; background: none; border: 0; cursor: pointer; padding: 0; }
.cb-dl:hover, .cb-copy:hover { text-decoration: underline; }
pre.code.cb-code { margin: 0; border-radius: 0 0 var(--radius-sm) var(--radius-sm); max-height: 560px; overflow: auto; font-size: 13px; line-height: 1.55; }
.sim { margin: 26px 0 40px; }
.sim .segmented { margin-bottom: 18px; }
.sim-inputs { grid-template-columns: repeat(auto-fill, minmax(170px, 1fr)); }
#sim-chart { width: 100%; height: 320px; display: block; margin: 16px 0 6px; }
.sim .results { display: grid; grid-template-columns: repeat(auto-fill, minmax(170px, 1fr)); gap: 10px; }
.sim .result { cursor: default; } .sim .r-val { word-break: normal; }
.report > .prose { min-width: 0; } .equation.tex { max-width: 100%; }
@media (max-width: 600px) { .equation.tex .katex-display > .katex { font-size: 0.86em; } .equation.tex { padding-left: 14px; padding-right: 14px; } }
.sim canvas { width: 100%; height: 320px; display: block; margin: 16px 0 6px; }
/* ---------- citations ---------- */
.cite-wrap { white-space: normal; }
a.cite { color: inherit; text-decoration: none; border-bottom: 1px dotted var(--text-3); }
a.cite:hover { color: var(--link); border-bottom-color: var(--link); }
.refs-box { margin-top: 26px; padding-top: 16px; border-top: 1px solid var(--line-soft); }
.refs-title { font-size: 12px; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .06em; margin-bottom: 10px; }
ul.refs { list-style: none; padding: 0; margin: 0; }
ul.refs li { transition: background .4s; margin: 0 0 8px; padding-left: 1.4em; text-indent: -1.4em; font-size: 13.5px; color: var(--text-2); line-height: 1.5; }
ul.refs li:target, ul.refs li.hit { background: color-mix(in srgb, var(--accent) 12%, transparent); border-radius: 6px; }

ul.refs li { scroll-margin-top: 90px; }
.prose a.cite, .theory a.cite { color: inherit; text-decoration: none; border-bottom: 1px dotted var(--text-3); }
.prose a.cite:hover, .theory a.cite:hover { color: var(--link); border-bottom-color: var(--link); }
ul.refs a { word-break: normal; overflow-wrap: anywhere; }

.refs-page .refs-group { margin: 44px 0 14px; display: flex; align-items: baseline; gap: 10px; }
.refs-page .refs-count { font-size: 13px; font-weight: 500; color: var(--text-3); }
.refs-page ul.refs li { margin-bottom: 14px; font-size: 14.5px; }
.ref-uses { text-indent: 0; margin-top: 3px; font-size: 12.5px; color: var(--text-3); }
.ref-uses a { color: var(--text-3); }
.ref-uses a:hover { color: var(--link); }
.equation.tex { position: relative; } .katex .katex-mathml { max-width: 1px; }
footer .foot-links { flex-wrap: wrap; gap: 8px 20px; }
@media (max-width: 480px) { .sim .segmented { display: flex; } .sim .segmented button { white-space: nowrap; padding-left: 10px; padding-right: 10px; font-size: 13px; flex: 1 1 auto; } }
.theory p.check { border-left: 3px solid var(--line); padding-left: 12px; color: var(--text-2); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .result.primary { background: #0062c4; } }

[id] { scroll-margin-top: 110px; }
.eyebrow.blue { color: #0066cc; }
.or-ok { background: #17803f; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .btn:not(.ghost):not(:hover), :root:not([data-theme="light"]) .pill:not(:hover), :root:not([data-theme="light"]) .or-use { background: #0062c4; }
  :root:not([data-theme="light"]) .eyebrow.blue { color: #409cff; } :root:not([data-theme="light"]) .or-ok { background: #1e7a3b; }
  :root:not([data-theme="light"]) .or-msg.ok { color: #30d158; } :root:not([data-theme="light"]) .or-msg.warn { color: #ffb340; } :root:not([data-theme="light"]) .or-msg.bad { color: #ff6961; } }
.prose h2.h3 { font-size: 24px; margin: 44px 0 12px; line-height: 1.2; }
.theory .h4 { font-size: 17px; font-weight: 600; letter-spacing: -0.01em; margin: 26px 0 8px; color: var(--text); }
.theory .or-chk { margin: 14px 0 6px; }
.theory .or-chk th { text-align: left; }
.or-xt td { white-space: normal; vertical-align: top; font-variant-numeric: tabular-nums; }
.or-xt td:nth-child(2) { white-space: nowrap; }
.or-xt td.or-rec { min-width: 160px; }
/* O-ring info buttons and popovers */
.or-i { display: inline-flex; align-items: center; justify-content: center; width: 17px; height: 17px; padding: 0; margin-left: 3px; vertical-align: 1px; border-radius: 50%; border: 1px solid var(--text-3); background: transparent; color: var(--text-3); font: italic 600 11px/1 Georgia, 'Times New Roman', serif; cursor: pointer; flex: none; text-transform: none; letter-spacing: 0; }
.or-i:hover, .or-i[aria-expanded="true"] { border-color: var(--accent); color: #fff; background: var(--accent); }
.or-i:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.h3 .or-i { vertical-align: 4px; }
.or-pop { position: absolute; z-index: 1000; width: min(360px, calc(100vw - 24px)); background: var(--bg); color: var(--text-2); border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 12px 40px rgba(0, 0, 0, .18); font-size: 14px; line-height: 1.5; padding: 14px 16px 6px; }
.or-pop-h { display: flex; justify-content: space-between; align-items: flex-start; gap: 10px; color: var(--text); font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.or-pop-x { border: 0; background: none; color: var(--text-3); font-size: 20px; line-height: 1; cursor: pointer; padding: 0 2px; }
.or-pop-x:hover { color: var(--text); }
.or-pop p, .or-pop ul { margin: 0 0 8px; }
.or-pop ul { padding-left: 1.1em; }
.or-pop li + li { margin-top: 3px; }
@media print { .or-i, .or-pop { display: none !important; } }
.or-guide { margin-bottom: 22px; padding: 0; }
.or-guide summary { list-style: none; cursor: pointer; padding: 20px 28px; display: flex; flex-direction: column; gap: 4px; }
.or-guide summary::-webkit-details-marker { display: none; }
.or-guide-t { font-size: 19px; font-weight: 600; color: var(--text); }
.or-guide-t::after { content: '›'; display: inline-block; margin-left: 8px; color: var(--text-3); transition: transform .2s; }
.or-guide[open] .or-guide-t::after { transform: rotate(90deg); }
.or-guide-s { font-size: 14px; color: var(--text-3); }
.or-i-demo { cursor: default; display: inline-flex; vertical-align: 0; }
.or-guide-b { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; padding: 0 28px 24px; font-size: 15px; line-height: 1.55; color: var(--text-2); }
.or-guide-b .h4 { font-size: 16px; font-weight: 600; color: var(--text); margin: 6px 0 8px; }
.or-guide-b p { margin: 0 0 10px; }
.or-guide-b ol, .or-guide-b ul { margin: 0 0 12px 1.2em; padding: 0; }
.or-guide-b li + li { margin-top: 5px; }
@media (max-width: 760px) { .or-guide-b { grid-template-columns: 1fr; gap: 6px; padding: 0 18px 18px; } .or-guide summary { padding: 16px 18px; } }
@media (max-width: 1000px) { .or-grid { grid-template-columns: minmax(0, 1fr); } }
.or-grid > .or-card { min-width: 0; }
@media (max-width: 560px) { .or-xt td.or-rec { min-width: 0; } .or-xt td { font-size: 13px; } }