:root {
  --ink: #1d1d1f;
  --muted: #6e6e73;
  --line: #dedede;
  --accent: #0f6b62;
  --accent-soft: #e8f2ef;
  --paper: #fffefa;
  color: var(--ink);
  background: var(--paper);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
body { margin: 0; }
button, input { font: inherit; }
.explorer { padding: 28px; }
.explorer-app { display: none; }
.file-fallback { display: block; max-width: 920px; padding: 24px; border: 1px solid var(--line); border-radius: 12px; background: #f6f6f4; }
.file-fallback h1 { margin: 0 0 10px; font-family: Georgia, "Times New Roman", serif; font-size: 2rem; font-weight: 500; letter-spacing: -0.03em; }
.file-fallback p { margin: 0 0 18px; line-height: 1.55; }
.file-fallback figure { margin: 0; }
.file-fallback img { display: block; width: 100%; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); }
.file-fallback figcaption { margin-top: 10px; color: var(--muted); font-size: 0.9rem; line-height: 1.5; }
.js .explorer-app { display: block; }
.js .file-fallback { display: none; }
.show-fallback .explorer-app { display: none; }
.show-fallback .file-fallback { display: block; }

.explorer-header { max-width: 68ch; margin-bottom: 22px; }
.kicker { margin: 0 0 8px; color: var(--accent); font-size: 0.74rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; }
h1, h2, h3, p { margin-top: 0; }
h1 { margin-bottom: 10px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(1.8rem, 3.6vw, 2.7rem); font-weight: 500; letter-spacing: -0.035em; line-height: 1.04; }
h2 { margin-bottom: 8px; font-size: 1rem; }
h3 { margin-bottom: 5px; font-size: 0.86rem; }
p, label, button, dt, dd, li { font-size: 0.92rem; line-height: 1.48; }
.explorer-header > p:last-child { margin-bottom: 0; color: #3d3d40; }

.explorer-layout { display: grid; gap: 16px; }
.diagram-panel { min-width: 0; padding: 14px; border: 1px solid var(--line); border-radius: 12px; background: #fff; }
#ray-diagram { display: block; width: 100%; height: auto; }
.diagram-note { margin: 8px 2px 0; color: var(--muted); font-size: 0.78rem; line-height: 1.42; }
.ray-key { display: flex; flex-wrap: wrap; gap: 6px 12px; margin: 10px 2px 0; color: #3d3d40; font-size: 0.78rem; }
.ray-key-item { display: inline-flex; align-items: center; gap: 5px; }
.ray-key-swatch { display: block; flex: 0 0 26px; width: 26px; height: 13px; }
.intercept-list { margin-top: 10px; padding: 10px 12px; border-left: 4px solid var(--accent); border-radius: 0 8px 8px 0; background: var(--accent-soft); }
.intercept-list h3 { margin: 0 0 2px; }
.intercept-list p { margin: 0; color: #254b47; font-size: 0.82rem; }
.intercept-list ul { display: flex; flex-wrap: wrap; gap: 3px 13px; margin: 5px 0 0; padding: 0; list-style: none; }
.intercept-list li { font-size: 0.79rem; line-height: 1.35; }
.intercept-list li::before { content: "•"; margin-right: 4px; color: var(--accent); }
.intercept-list li.is-clipped { color: #8a3c1f; font-weight: 700; }
.intercept-list li.is-clipped::before { content: "↟"; }

.controls-panel { display: grid; grid-template-columns: minmax(220px, 1fr) minmax(220px, 1fr) minmax(220px, 1fr); gap: 14px; align-items: stretch; }
.controls-panel > form, .matrix-card, .focus-card { min-width: 0; padding: 14px; border: 1px solid var(--line); border-radius: 10px; background: #fff; }
.controls-panel > form { background: #fbfcfa; }
fieldset { margin: 0; padding: 0; border: 0; }
legend { margin-bottom: 9px; font-size: 0.88rem; font-weight: 700; }
label { display: block; margin-top: 8px; font-weight: 650; }
label:first-of-type { margin-top: 0; }
label > span { display: block; }
output { display: block; margin-top: 1px; color: var(--accent); font-variant-numeric: tabular-nums; }
input[type="range"] { width: 100%; margin-top: 2px; accent-color: var(--accent); }
.button-row { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 8px; margin-top: 11px; }
button { padding: 8px 9px; border: 1px solid var(--accent); border-radius: 8px; color: #fff; background: var(--accent); font-size: 0.83rem; font-weight: 700; cursor: pointer; }
button:hover { background: #0b574f; }
.secondary-button { color: #0b514a; background: white; }
.secondary-button:hover { background: var(--accent-soft); }

.matrix-card { background: #f6f6f4; }
.matrix-card h2, .focus-card h2 { margin-bottom: 3px; }
.matrix-context { margin-bottom: 8px; color: var(--muted); font-size: 0.8rem; }
.matrix-grid { display: grid; grid-template-columns: 1fr 1fr; overflow: hidden; border: 1px solid #cfd3cf; border-radius: 8px; background: white; }
.matrix-grid > div { display: grid; grid-template-columns: auto minmax(0, 1fr); column-gap: 5px; align-items: baseline; min-height: 44px; padding: 6px 8px; border-right: 1px solid #dfe2df; border-bottom: 1px solid #dfe2df; }
.matrix-grid > div:nth-child(2n) { border-right: 0; }
.matrix-grid > div:nth-last-child(-n + 2) { border-bottom: 0; }
.matrix-grid span { font-family: Georgia, "Times New Roman", serif; font-size: 0.96rem; }
.matrix-grid output { margin: 0; color: var(--ink); font-size: 0.9rem; font-weight: 700; text-align: right; }
.matrix-grid small { grid-column: 2; color: var(--muted); font-size: 0.68rem; text-align: right; }
.operator-product { margin: 10px 0 5px; color: #303336; font-family: Georgia, "Times New Roman", serif; font-size: 0.82rem; line-height: 1.45; }
.operator-product i { font-style: italic; }
.operator-product sub { font-family: Inter, ui-sans-serif, sans-serif; font-size: 0.7em; }
.matrix-note { margin: 0; color: var(--muted); font-size: 0.75rem; line-height: 1.4; }

.focus-card { background: #fff; }
.focus-status { display: inline-block; margin: 7px 0 9px; padding: 5px 8px; border-radius: 999px; color: #0b514a; background: var(--accent-soft); font-size: 0.83rem; font-weight: 800; }
.focus-status.is-near { color: #7a5200; background: #fff2c7; }
.focus-status.is-defocused { color: #8a3c1f; background: #fbe8df; }
dl { margin: 0; }
dl > div { display: flex; justify-content: space-between; gap: 10px; padding: 6px 0; border-top: 1px solid var(--line); }
dt, dd { margin: 0; }
dt { color: #424247; font-size: 0.78rem; }
dd { flex: 0 0 auto; color: var(--ink); font-size: 0.82rem; font-variant-numeric: tabular-nums; font-weight: 750; text-align: right; }
#focus-explanation { margin: 9px 0 0; color: #3d3d40; font-size: 0.79rem; line-height: 1.43; }
.paraxial-check { margin-top: 10px; padding-top: 10px; border-top: 1px solid var(--line); }
.paraxial-check h3 { margin-bottom: 4px; }
.paraxial-status { display: inline-block; margin: 0 0 6px; padding: 4px 7px; border-radius: 999px; color: #0b514a; background: var(--accent-soft); font-size: 0.76rem; font-weight: 800; }
.paraxial-status.is-marginal { color: #7a5200; background: #fff2c7; }
.paraxial-status.is-nonparaxial { color: #8a3c1f; background: #fbe8df; }
.paraxial-check dl > div { padding: 4px 0; }
.paraxial-check dt, .paraxial-check dd { font-size: 0.74rem; }
#paraxial-explanation { margin: 7px 0 0; color: #3d3d40; font-size: 0.75rem; line-height: 1.4; }

.visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

html.embedded, html.embedded body { min-height: 100%; }
.embedded .explorer { padding: 14px; }
.embedded .explorer-header { display: none; }
.embedded .diagram-panel { padding: 10px; }
.embedded #ray-diagram { width: 100%; max-width: none; height: auto; margin: 0; }
.embedded .diagram-note { display: none; }
.embedded .ray-key { margin-top: 6px; }
.embedded .intercept-list { margin-top: 7px; padding: 8px 10px; }
.embedded .controls-panel { gap: 10px; }
.embedded .controls-panel > form, .embedded .matrix-card, .embedded .focus-card { padding: 11px; }
.embedded label { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: baseline; margin-top: 3px; font-size: 0.78rem; line-height: 1.15; }
.embedded label > span { display: inline; }
.embedded label output { grid-column: 2; grid-row: 1; margin: 0; text-align: right; }
.embedded label + input { margin-top: 0; }
.embedded legend { font-size: 0.8rem; }
.embedded output, .embedded input, .embedded button { font-size: 0.78rem; }
.embedded .matrix-context, .embedded .matrix-note, .embedded #focus-explanation, .embedded #paraxial-explanation { font-size: 0.68rem; }
.embedded .matrix-grid > div { min-height: 37px; padding: 4px 6px; }
.embedded .matrix-grid output { font-size: 0.78rem; }
.embedded .focus-status { margin: 5px 0 6px; padding: 4px 7px; font-size: 0.73rem; }
.embedded dl > div { padding: 4px 0; }
.embedded dt, .embedded dd { font-size: 0.72rem; }
.embedded .paraxial-check { margin-top: 7px; padding-top: 7px; }
.embedded .paraxial-status { margin-bottom: 4px; padding: 3px 6px; font-size: 0.67rem; }
.embedded .paraxial-check dt, .embedded .paraxial-check dd { font-size: 0.66rem; }
.embedded #focus-explanation, .embedded #paraxial-explanation, .embedded .paraxial-check h3 { display: none; }
.embedded .paraxial-check { margin-top: 5px; padding-top: 5px; }
.embedded .paraxial-check dl { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 0 6px; }
.embedded .paraxial-check dl > div { display: block; min-width: 0; padding: 2px 0; border-top: 0; }
.embedded .paraxial-check dd { text-align: left; }

@media (max-width: 760px) {
  .explorer { padding: 18px; }
  .controls-panel { grid-template-columns: 1fr; }
}

@media (max-width: 760px) and (min-width: 560px) {
  .embedded .controls-panel { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) minmax(0, 1fr); }
}

@media (max-width: 559px) {
  .embedded .explorer { padding: 10px; }
  .embedded .controls-panel { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
  .embedded .focus-card { grid-column: 1 / -1; }
}