@import url("../../../assets/fonts/fonts.css");
/* Layout: the knee on the left, its histogram and the REX scale on the right, controls beside them on a
   normal screen and under them on a narrow one. Shares its look with the shadow simulator.
   Dark on purpose, the same world as the video. */
:root {
  --bg: #0A0E18;        /* the video's background */
  --panel: #121A2B;
  --line: #26304A;
  --fg: #E6E9F0;
  --muted: #8E97AC;
  --signal: #5EE7DF;    /* primary photons */
  --hot: #FF4D6D;       /* the error: penumbra, blur, wrong outline */
  --amber: #F5A623;     /* what you adjust */
  --bone: #E8E8E8;
  --soft: #5A5F6B;
  --display: "Source Serif 4", Georgia, "Times New Roman", serif;
  --body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  color-scheme: dark;
}
html { background: var(--bg); }
body {
  background: var(--bg); color: var(--fg); font-family: var(--body); font-size: 15px; line-height: 1.5;
  padding-block: 20px 40px;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.wrap { max-width: 1120px; margin: 0 auto; display: grid; gap: 20px; }
header { display: flex; flex-wrap: wrap; gap: 12px 24px; align-items: end; justify-content: space-between; }
h1 { font-family: var(--display); font-weight: 600; font-size: clamp(26px, 4vw, 36px); margin: 0; text-wrap: balance; }
.sub { color: var(--muted); margin: 4px 0 0; max-width: 62ch; }
.toggles { display: flex; gap: 10px; flex-wrap: wrap; }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 6px; overflow: hidden; }
.seg button {
  background: transparent; color: var(--muted); border: 0; padding: 6px 12px; font: 500 13px var(--body); cursor: pointer;
}
.seg button[aria-pressed="true"] { background: var(--line); color: var(--fg); }
.seg button:focus-visible, input:focus-visible, summary:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }

.stage { display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr); gap: 16px; }
.stage .controls { order: 3; grid-column: 1 / -1; }
@media (max-width: 780px) { .stage { grid-template-columns: minmax(0, 1fr); } }
.box { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 12px; min-width: 0; }
.box h2 { font: 600 12px var(--body); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); margin: 0 0 8px; }
canvas { display: block; width: 100%; }
#knee { aspect-ratio: 1 / 1; max-width: 420px; margin: 0 auto; }
#hist { aspect-ratio: 1.6 / 1; }
.knee-box .note { text-align: center; }
.right { display: grid; gap: 12px; align-content: start; }
.note { color: var(--muted); font-size: 12px; margin: 6px 0 0; }

.readout { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; }
@media (max-width: 460px) { .readout { grid-template-columns: minmax(0, 1fr); } }
.metric { border-left: 3px solid var(--line); padding: 2px 0 2px 10px; }
.metric .k { color: var(--muted); font-size: 12px; }
.metric .v { font: 500 18px var(--mono); font-variant-numeric: tabular-nums; }
.metric .f { font: 12px var(--mono); color: var(--signal); margin-top: 2px; }
.metric.err { border-color: var(--hot); }
.metric.mag { border-color: var(--amber); }
.metric.ok { border-color: var(--signal); }
.metric .v.ok { color: var(--signal); }
.metric .v.bad { color: var(--hot); }
.ctl .reset { margin-top: 4px; background: transparent; color: var(--muted); border: 1px solid var(--line);
  border-radius: 6px; padding: 6px 12px; font: 500 13px var(--body); cursor: pointer; }
.ctl .reset:hover { color: var(--fg); }

.controls { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px 22px; }
.ctl label { display: flex; justify-content: space-between; gap: 8px; font-size: 13px; }
.ctl label span:last-child { font: 500 13px var(--mono); color: var(--amber); font-variant-numeric: tabular-nums; }
.ctl input[type=range] { width: 100%; accent-color: var(--amber); }
.ctl .seg { margin-top: 4px; }

.tasks { display: grid; gap: 8px; }
details { border: 1px solid var(--line); border-radius: 6px; padding: 10px 12px; background: var(--panel); }
summary { cursor: pointer; font-weight: 500; }
details p { margin: 8px 0 0; color: var(--muted); }
details .q { color: var(--fg); margin-top: 6px; }
details .a { border-left: 3px solid var(--signal); padding-left: 10px; }
h3 { font-family: var(--display); font-weight: 600; font-size: 22px; margin: 6px 0 0; }
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }

/* top bar back to the learning page, and the footer */
.back { color: var(--muted); font-size: 13px; text-decoration: none; }
.back:hover { color: var(--fg); }
.mt { margin-top: 10px; }
details.answer { border: 0; padding: 6px 0 0; background: none; }
footer { color: var(--muted); font-size: 12px; border-top: 1px solid var(--line); padding-top: 14px; }
footer a { color: var(--muted); }


/* Normal screens (laptop and up): three columns that together fill the window height. */
@media (min-width: 1100px) and (min-height: 600px) {
  body { padding-block: 12px 40px; }
  .wrap { max-width: 1680px; gap: 12px; }
  header { align-items: center; }
  .back { margin-bottom: -8px; }
  h1 { font-size: 26px; }
  .sub { font-size: 13px; margin-top: 0; max-width: none; }
  .stage {
    grid-template-columns: 250px minmax(0, 1fr) minmax(0, 1.25fr);
    height: calc(100svh - 128px); min-height: 480px;
  }
  .stage .controls {
    order: 0; grid-column: auto; grid-template-columns: minmax(0, 1fr);
    gap: 9px; overflow-y: auto; align-content: start;
  }
  .ctl label { font-size: 12.5px; }
  .knee-box { display: flex; flex-direction: column; min-height: 0; }
  #knee { width: min(100%, calc(100svh - 230px)); max-width: none; margin: auto; }
  .right { min-height: 0; grid-template-rows: minmax(0, 1fr) auto; }
  .right > .box:first-child { min-height: 0; display: flex; flex-direction: column; }
  #hist { aspect-ratio: auto; flex: 1; min-height: 0; }
  .metric .v { font-size: 15px; }
}