/* Sources & limitations — a modal register over the 3D page.
   Header → summary strip → tabs → one scrolling body. Phones get a full sheet. */
.src-sheet { width: min(1060px, calc(100vw - 32px)); height: min(880px, calc(100dvh - 40px)); max-width: none; max-height: none; margin: auto; padding: 0; border: 1px solid var(--line); border-radius: 20px; color: var(--ink); background: var(--panel); box-shadow: 0 24px 80px -20px rgba(20, 24, 26, .35); overflow: hidden; }
.src-sheet::backdrop { background: rgba(20, 30, 30, .42); backdrop-filter: blur(3px); }
.src-sheet[open] { animation: src-in .22s ease-out; }
@keyframes src-in { from { opacity: 0; transform: translateY(8px) scale(.98); } }
html[dir="rtl"] .src-sheet, .src-sheet[dir="rtl"] { font-family: var(--font-ar); }
.src-shell { display: grid; grid-template-rows: auto auto auto minmax(0, 1fr); height: 100%; }

.src-header { display: flex; align-items: flex-start; justify-content: space-between; gap: 24px; padding: 26px 30px 18px; }
.src-eyebrow { margin: 0 0 8px; color: var(--teal); font: 500 .66rem/1 var(--font-mono); letter-spacing: .14em; }
.src-sheet[dir="rtl"] .src-eyebrow { font-family: var(--font-ar); letter-spacing: 0; font-size: .74rem; }
.src-header h2 { margin: 0; font: 500 clamp(1.5rem, 2.6vw, 2.1rem)/1.05 var(--font-display); letter-spacing: -.02em; }
.src-sheet[dir="rtl"] .src-header h2 { font-family: var(--font-ar); font-weight: 700; letter-spacing: 0; }
.src-header p:last-child { max-width: 620px; margin: 8px 0 0; color: var(--muted); font-size: .84rem; line-height: 1.6; }
.src-close { flex: 0 0 auto; display: grid; place-items: center; width: 40px; height: 40px; border: 1px solid var(--line-strong); border-radius: 12px; color: var(--muted); background: var(--panel); cursor: pointer; transition: color .15s ease-out, background-color .15s ease-out, transform .12s ease-out; }
.src-close:hover { color: var(--ink); background: var(--sunken); }
.src-close:active { transform: scale(.94); }
.src-close svg { width: 18px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; }

.src-summary { display: grid; grid-template-columns: repeat(4, 1fr); margin: 0 30px; border-block: 1px solid var(--line); }
.src-summary div { display: grid; gap: 4px; padding: 12px 16px; border-inline-start: 1px solid var(--line); }
.src-summary div:first-child { border-inline-start: 0; padding-inline-start: 0; }
.src-summary dt { color: var(--teal-strong); font: 500 1.1rem/1.1 var(--font-display); font-variant-numeric: tabular-nums; }
.src-summary dd { margin: 0; color: var(--faint); font-size: .68rem; }

.src-tabs { display: flex; gap: 4px; padding: 14px 30px 0; overflow-x: auto; scrollbar-width: none; border-bottom: 1px solid var(--line); }
.src-tabs::-webkit-scrollbar { display: none; }
.src-tabs button { position: relative; flex: 0 0 auto; min-height: 42px; padding: 0 14px; border: 0; border-radius: 10px 10px 0 0; color: var(--muted); background: transparent; font-size: .78rem; font-weight: 700; cursor: pointer; transition: color .15s ease-out, background-color .15s ease-out; }
.src-tabs button:hover { color: var(--ink); background: var(--panel-2); }
.src-tabs button[aria-selected="true"] { color: var(--teal-strong); }
.src-tabs button[aria-selected="true"]::after { content: ""; position: absolute; inset-inline: 10px; bottom: -1px; height: 2px; border-radius: 2px; background: var(--teal); }
.src-tabs button:focus-visible, .src-sheet a:focus-visible, .src-cite:focus-visible, .src-close:focus-visible { outline: 2px solid var(--teal-mid); outline-offset: 2px; }

.src-body { overflow-y: auto; padding: 22px 30px 34px; scrollbar-width: thin; scrollbar-color: rgba(31, 75, 76, .28) transparent; }
.src-body:focus-visible { outline: none; }
.src-lead { max-width: 760px; margin: 0 0 18px; color: var(--muted); font-size: .82rem; line-height: 1.65; }
.src-group { margin-top: 26px; }
.src-group:first-of-type { margin-top: 0; }
.src-legend + .src-group { margin-top: 22px; }
.src-group h3, .src-limits h3 { display: flex; align-items: center; gap: 8px; margin: 0 0 10px; color: var(--ink); font-size: .9rem; }
.src-group h3 span { padding: 1px 8px; border-radius: 999px; color: var(--teal); background: var(--teal-soft); font: 600 .62rem/1.5 var(--font-mono); }

.src-legend { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 8px; margin: 0; padding: 0; list-style: none; }
.src-legend li { display: grid; gap: 6px; align-content: start; padding: 10px 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel-2); color: var(--muted); font-size: .68rem; line-height: 1.5; }
.src-legend .src-basis { justify-self: start; }

.src-basis, .src-support { display: inline-block; padding: 3px 9px; border-radius: 999px; font-size: .62rem; font-weight: 700; font-style: normal; white-space: nowrap; }
.src-basis--reference, .src-support--population { color: var(--teal-strong); background: #d3e6e4; }
.src-basis--approximation, .src-support--trend { color: var(--amber-ink); background: var(--amber-soft); }
.src-basis--derived { color: #2f4f73; background: #e1e9f3; }
.src-basis--teaching, .src-support--model { color: var(--muted); background: var(--sunken); }

.src-table { width: 100%; border-collapse: collapse; font-size: .76rem; }
.src-table th { padding: 8px 12px; border-bottom: 1px solid var(--line-strong); color: var(--faint); font: 500 .62rem/1.3 var(--font-mono); letter-spacing: .08em; text-align: start; text-transform: uppercase; }
.src-sheet[dir="rtl"] .src-table th { font-family: var(--font-ar); letter-spacing: 0; font-size: .7rem; }
.src-table td { padding: 12px; border-bottom: 1px solid var(--line); vertical-align: top; line-height: 1.55; }
.src-table tr:last-child td { border-bottom: 0; }
.src-table tbody tr:hover { background: var(--panel-2); }
.src-table td:nth-child(1) { width: 16%; }
.src-table td:nth-child(2) { width: 30%; color: var(--ink); font-weight: 600; }
.src-table td:nth-child(3) { width: 15%; }
.src-table td p { margin: 0 0 7px; color: var(--muted); }
.src-value { color: var(--teal-strong); font: 600 .78rem/1.4 var(--font-mono); white-space: nowrap; direction: ltr; unicode-bidi: isolate; }
.src-none { color: var(--faint); font-size: .66rem; font-style: italic; }

.src-cites { display: flex; flex-wrap: wrap; gap: 5px; }
.src-cite { display: inline-flex; align-items: center; gap: 6px; min-height: 28px; padding-block: 0; padding-inline: 4px 10px; border: 1px solid var(--teal-line); border-radius: 999px; color: var(--teal); background: var(--panel); font: 600 .64rem/1 var(--font-ui); cursor: pointer; transition: background-color .15s ease-out, transform .12s ease-out; }
html[dir="rtl"] .src-cite { font-family: var(--font-ar); }
.src-cite b { display: grid; place-items: center; min-width: 20px; height: 20px; padding: 0 4px; border-radius: 999px; color: var(--on-accent); background: var(--teal); font: 600 .58rem/1 var(--font-mono); }
.src-cite:hover { background: var(--teal-soft); }
.src-cite:active { transform: scale(.96); }

.src-cards { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.src-card { display: grid; align-content: start; gap: 10px; padding: 16px 18px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel-2); }
.src-card header { display: flex; flex-wrap: wrap; align-items: baseline; gap: 6px 10px; }
.src-card header strong { color: var(--teal-strong); font: 600 .84rem/1.2 var(--font-mono); }
.src-card header span { color: var(--ink); font-size: .78rem; font-weight: 700; }
.src-card header em { margin-inline-start: auto; }
.src-card > p { margin: 0; color: var(--ink); font-size: .76rem; line-height: 1.65; }
.src-card .src-note { padding: 8px 10px; border-inline-start: 2px solid var(--amber); border-radius: 0 8px 8px 0; color: var(--muted); background: var(--panel); font-size: .7rem; }
.src-card dl { display: grid; gap: 6px; margin: 0; }
.src-card dl div { display: grid; grid-template-columns: minmax(110px, auto) 1fr; gap: 10px; font-size: .7rem; line-height: 1.5; }
.src-card dt { color: var(--faint); }
.src-card dd { margin: 0; color: var(--muted); }

.src-limits { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.src-limits section { padding: 16px 18px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel-2); }
.src-limits ul { display: grid; gap: 8px; margin: 0; padding-inline-start: 18px; color: var(--muted); font-size: .76rem; line-height: 1.6; }
.src-limits li::marker { color: var(--amber); }

.src-references { display: grid; gap: 8px; margin: 0; padding: 0; list-style: none; }
.src-references li { display: grid; grid-template-columns: 28px minmax(0, 1fr); gap: 12px; padding: 13px 15px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); scroll-margin: 20px; transition: border-color .3s ease-out, background-color .3s ease-out, box-shadow .3s ease-out; }
.src-references li.is-cited { border-color: var(--teal-mid); background: var(--teal-soft); box-shadow: 0 0 0 3px rgba(47, 138, 134, .14); }
.src-number { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; color: var(--on-accent); background: var(--teal); font: 600 .68rem/1 var(--font-mono); }
.src-references h4 { margin: 2px 0 5px; color: var(--ink); font-size: .82rem; line-height: 1.45; }
.src-references p { margin: 0 0 5px; font-size: .7rem; line-height: 1.55; }
.src-byline { color: var(--muted); }
.src-byline i { color: var(--ink); }
.src-design { color: var(--faint); }
.src-uses { display: flex; flex-wrap: wrap; align-items: center; gap: 5px; color: var(--faint); }
.src-uses span { margin-inline-end: 3px; }
.src-uses em { padding: 1px 7px; border: 1px solid var(--teal-line); border-radius: 6px; color: var(--teal); background: var(--panel-2); font-size: .64rem; font-style: normal; font-weight: 600; }
.src-references .src-links { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 0; }
.src-links a { display: inline-flex; align-items: center; gap: 4px; min-height: 28px; padding: 0 10px; border: 1px solid var(--line-strong); border-radius: 8px; color: var(--teal); background: var(--panel-2); font-size: .66rem; font-weight: 700; text-decoration: none; transition: border-color .15s ease-out, background-color .15s ease-out; }
.src-links a::after { content: "↗"; font-size: .7rem; }
.src-links a:hover { border-color: var(--teal); background: var(--teal-soft); }

/* Entry points */
.model-note__sources { display: inline-flex; flex: 0 0 auto; align-items: center; gap: 8px; min-height: 36px; padding: 0 12px; border: 1px solid var(--teal-line); border-radius: 10px; color: var(--teal); background: var(--panel); font-size: .72rem; font-weight: 700; cursor: pointer; transition: background-color .15s ease-out, transform .12s ease-out; }
.model-note__sources b { padding: 1px 7px; border-radius: 999px; color: var(--on-accent); background: var(--teal); font: 600 .6rem/1.5 var(--font-mono); }
.model-note__sources:hover { background: var(--teal-soft); }
.model-note__sources:active { transform: scale(.97); }
.biometry-sources-open { display: flex; align-items: center; justify-content: space-between; gap: 10px; min-height: 40px; padding: 0 12px; border: 1px solid var(--teal-line); border-radius: 10px; color: var(--teal); background: var(--panel); font-size: .7rem; font-weight: 700; cursor: pointer; transition: background-color .15s ease-out, transform .12s ease-out; }
.biometry-sources-open:hover { background: var(--teal-soft); }
.biometry-sources-open:active { transform: scale(.97); }

@media (max-width: 900px) {
  .src-legend { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .src-cards, .src-limits { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .src-sheet { width: 100vw; height: 100dvh; border: 0; border-radius: 0; }
  .src-header { padding: 18px 16px 12px; }
  .src-summary { grid-template-columns: 1fr 1fr; margin: 0 16px; }
  .src-summary div { padding: 9px 10px; }
  .src-summary div:nth-child(3) { border-inline-start: 0; padding-inline-start: 0; border-top: 1px solid var(--line); }
  .src-summary div:nth-child(4) { border-top: 1px solid var(--line); }
  .src-tabs { padding: 10px 16px 0; }
  .src-tabs button { min-height: 44px; }
  .src-body { padding: 18px 16px 28px; }
  .src-legend { grid-template-columns: 1fr; }
  /* Rows become cards on a phone: value + basis on top, then definition, then note. */
  .src-table thead { display: none; }
  .src-table, .src-table tbody, .src-table tr, .src-table td { display: block; width: auto !important; }
  .src-table tr { margin-bottom: 8px; padding: 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel-2); }
  .src-table td { padding: 0; border: 0; }
  .src-table td:nth-child(1), .src-table td:nth-child(3) { display: inline-block; margin-bottom: 6px; }
  .src-table td:nth-child(3) { margin-inline-start: 8px; }
  .src-table td:nth-child(2) { margin-bottom: 6px; }
  .src-cite, .src-links a { min-height: 36px; }
  .src-card dl div { grid-template-columns: 1fr; gap: 2px; }
}
@media (prefers-reduced-motion: reduce) {
  .src-sheet[open] { animation: none; }
  .src-close, .src-tabs button, .src-cite, .src-references li, .src-links a, .model-note__sources, .biometry-sources-open { transition: none; }
}