/* The Calm Lung — shared styles.
   Tokens and rules come from docs/style-guide.md. When this file and that guide
   disagree, the guide wins and this file is wrong.

   Two layers, never mixed (guide §1): the claims layer says something about the
   biology and is schematic and labelled; the atmosphere layer says nothing and so
   cannot be wrong. Anything in here named .atmos-* belongs to the second kind and
   must never carry meaning. */

:root {
  /* daylight surfaces and ink */
  --paper: #fbf3ea;
  --paper-deep: #f3e6d6;
  --card: #fffdfa;
  --ink: #3a2320;
  --ink-soft: #6e5550;
  --rule: #e4d3c2;

  /* roles — a colour means the same thing everywhere (guide §2) */
  --tissue: #c2434d;   /* 4.5:1 on --paper; #c8454f was 4.3:1 */
  --tissue-soft: #f2c9c6;
  --immune: #007e74;   /* 4.5:1 on --paper; #008f84 was 3.6:1 */
  --immune-soft: #bfe6df;
  --virus: #d9962b;
  --worm: #b89a63;
  --molecule: #6b4fa8;
  --fight: #e0603a;
  --calm: #3aa58f;

  /* the microscope room */
  --scope: #0d111c;
  --scope-2: #161d2e;
  --scope-ink: #e8edf6;
  --scope-soft: #9aa6bd;
  --ch-virus: #b07d24;
  --ch-neut: #2196c8;
  --ch-damage: #d24e96;
  --glow-virus: #ffd27a;
  --glow-neut: #7fd4ff;
  --glow-damage: #ff8fc8;

  --display: "Fraunces", Georgia, serif;
  --text: "Inter", system-ui, -apple-system, sans-serif;

  --read: 720px;    /* one column of reading */
  --wide: 1060px;   /* exhibits may go wider */
  --gutter: 24px;
}

@media (max-width: 720px) { :root { --gutter: 16px; } }

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 17px/1.6 var(--text);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 { font-family: var(--display); font-weight: 600; line-height: 1.12; margin: 0; }
p { margin: 0 0 1em; }
a { color: inherit; }


.wide { max-width: var(--wide); margin: 0 auto; padding: 0 var(--gutter); }

.kicker {
  font: 600 12px/1 var(--text);
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--tissue);
  margin: 0 0 10px;
}

.lead { font-size: 20px; color: var(--ink-soft); }

/* skip link — keyboard users land here first */
.skip {
  position: absolute; left: -9999px; top: 0; z-index: 99;
  background: var(--ink); color: var(--paper);
  padding: 12px 18px; border-radius: 0 0 10px 0; font-weight: 600;
}
.skip:focus { left: 0; }

:focus-visible { outline: 3px solid var(--immune); outline-offset: 3px; border-radius: 4px; }

/* ---------------------------------------------------------------- placards
   Three depths, same picture (guide §6). The visitor chooses; the default is
   "For everyone". Every depth is in the DOM at all times so that find-in-page,
   screen readers in browse mode, and printing all reach the full text. */

.placard {
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 16px;
  padding: 20px 22px 6px;
  margin: 22px 0;
}

.placard-depths {
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 12px;
}

.placard-depths button {
  font: 500 14px/1 var(--text);
  color: var(--ink-soft);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 11px 15px;          /* >= 40px tap target with the line-height */
  min-height: 40px;
  cursor: pointer;
}
/* On a narrow screen these three used to wrap to two rows and stop reading as
   one control. Tighter type and padding keeps them on a single line; the tap
   target stays at 40px via min-height. */
@media (max-width: 460px) {
  .placard-depths { gap: 4px; }
  .placard-depths button { font-size: 13px; padding: 11px 9px; }
}
.placard-depths button:hover { background: var(--paper-deep); }
.placard-depths button[aria-selected="true"] {
  background: var(--immune-soft);
  border-color: var(--immune);
  color: var(--ink);
  font-weight: 600;
}

/* Without JavaScript every depth stays visible and the page still reads as a
   complete explainer; the tab strip only exists once JS can unfold it again. */
.placard-depths { display: none; }
.js .placard-depths { display: flex; }
.js .placard-body > div { display: none; }
.js .placard-body > div.is-shown { display: block; }

/* the depth's own label, for the no-JS reading and for print */
.placard-body > div > h4 {
  font: 600 12px/1 var(--text);
  letter-spacing: .14em; text-transform: uppercase;
  color: var(--ink-soft);
  margin: 0 0 8px;
}
.js .placard-body > div > h4 { position: absolute; left: -9999px; }
.placard-body p:last-child { margin-bottom: 1em; }

/* kids' placards run one size larger (guide §3) */
.placard-body .for-kids { font-size: 21px; line-height: 1.55; }
.placard-body .for-scientists { font-size: 16px; }

/* claim chips: where a statement comes from. Scientists' depth only (guide §6). */
.chips { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 14px; padding: 0; list-style: none; }
.chips li {
  font: 500 11px/1 var(--text);
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--ink-soft);
  background: var(--paper-deep);
  border: 1px solid var(--rule);
  border-radius: 999px;
  padding: 6px 9px;
}
.chips li.is-background { background: transparent; border-style: dashed; }

/* ------------------------------------------------------------- honesty notes */

.honesty {
  font-size: 13px;
  line-height: 1.5;
  color: var(--ink-soft);
  margin-top: 10px;
  font-style: italic;
}

/* Every animation has a still equivalent and a way back to the start
   (guide §5). The controls row sits under the exhibit, never over it. */
/* The controls drive JS-built animation, so without JS they promise something
   that cannot happen. The placard carries the full meaning either way. */
.exhibit-controls { display: none; }
.js .exhibit-controls {
  display: flex; flex-wrap: wrap; gap: 8px; align-items: center;
  margin-top: 12px;
}
/* The exhibits draw themselves in JS, so without it the frame would be an empty
   lit box under a caption for a picture that is not there. Both collapse, and the
   noscript description takes their place. Keyed off the class the script itself
   adds, so this does not depend on :has() support. */
.exhibit-controls button {
  font: 500 14px/1 var(--text);
  min-height: 40px;
  padding: 11px 15px;
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 999px;
  color: var(--ink);
  cursor: pointer;
}
.exhibit-controls button:hover { background: var(--paper-deep); }
.exhibit-controls .hint { font-size: 13px; color: var(--ink-soft); }

/* ------------------------------------------------------------ atmosphere layer
   Says nothing. Soft, low opacity, never attention-seeking.

   It used to drift, on a 9-18s loop. It does not any more, and the reason is
   worth keeping: a blurred layer cannot be composited: the browser re-rasters
   the blur on every frame it moves, for as long as the page is open. Measured
   on one machine, idle, no interaction, against an 8.1% floor for a blank page:

       the page with the drift      37.3%
       the page without it          11.2%

   Twenty-six points of someone's processor, for a wander most readers never
   consciously notice. The blur stays, the colours stay, the positions stay;
   only the motion is gone, and still is what it looked like at the start of
   every cycle anyway. Frank saw this as 50% CPU on his own laptop.

   If this is ever animated again, animate something that is not blurred. */

.atmos { position: absolute; inset: 0; z-index: 0; pointer-events: none; overflow: hidden; }
.atmos span {
  position: absolute;
  border-radius: 50%;
  background: var(--c);
  opacity: .2;
  filter: blur(var(--b, 40px));
}

/* ------------------------------------------------------------------- arrival */

.arrival {
  position: relative;
  overflow: hidden;
  padding: clamp(72px, 12vw, 128px) 0 clamp(56px, 8vw, 96px);
  background:
    radial-gradient(1200px 520px at 18% 8%, #fde3dc 0%, transparent 62%),
    radial-gradient(900px 520px at 88% 82%, #ddf1ec 0%, transparent 62%),
    var(--paper);
}
.arrival .inner { position: relative; z-index: 2; }
.arrival h1 { font-size: clamp(40px, 7vw, 78px); letter-spacing: -.01em; }
.arrival h1 em { font-style: normal; color: var(--immune); }
.arrival .lead { max-width: 34em; margin-top: 20px; }

/* --------------------------------------------------------------------- rooms */

.room { padding: clamp(48px, 7vw, 88px) 0; }
.room h2 { font-size: clamp(28px, 4vw, 40px); }
/* Headings and body text share the exhibits' left edge rather than sitting in a
   narrower centred column, which read as a misalignment rather than a choice.
   The reading measure is set on the text, not on its container. */
.room-intro { max-width: 34em; margin-top: 14px; }
.room .honesty { max-width: 44em; }

hr.rule { border: 0; border-top: 1px solid var(--rule); margin: 0; }

/* ------------------------------------------------------------------- credits */

.credits { background: var(--paper-deep); padding: 56px 0 72px; font-size: 15px; }
.credits h2 { font-size: 26px; margin-bottom: 14px; }
.credits ul { padding-left: 1.1em; }
.credits li { margin-bottom: .5em; }

/* ------------------------------------------------------- reduced motion, last
   Turning animation off must not lose meaning (guide §5). Anything that moves
   to teach something also has a still state, so stopping it is safe. */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
}

.arrival .plate { margin-top: 38px; }
.arrival .lead { max-width: 34em; }
.arrival-close { margin-top: 34px; font-size: 21px; color: var(--ink); }

.credits { background: var(--paper-deep); padding: 64px 0 80px; }
.credits h2 { font-size: clamp(26px, 3.4vw, 36px); margin-bottom: 28px; }
.credit-cols { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(300px, 100%), 1fr)); gap: 36px; }
/* The footer's surface is --paper-deep, where the page colours measure about
   4.05:1. Darker variants, used only here. */
.credits { --immune: #00756c; --tissue: #b43d47; }
.credit-cols h3 { font-size: 15px; letter-spacing: .14em; text-transform: uppercase;
                  font-family: var(--text); font-weight: 600; color: var(--tissue); margin-bottom: 12px; }
.credit-cols p { font-size: 15.5px; max-width: 42em; }
.credit-cols .muted { color: var(--ink-soft); font-size: 14px; }
.credit-cols a { color: var(--immune); text-underline-offset: 3px; }

/* ------------------------------------------------- back out into the daylight */

.step-up { background: linear-gradient(var(--scope) 0%, #2a2d3a 28%, #cdbdb0 70%, var(--paper) 100%); }
.step-up .step-cue { bottom: auto; top: 96px; color: var(--ink-soft); }

/* ------------------------------------------------- three ways of asking (room A) */

.ways { list-style: none; margin: 10px 0 0; padding: 22px 28px 0; }
.way {
  display: grid;
  grid-template-columns: 34px 1fr 230px;
  gap: 18px; align-items: start;
  padding: 20px 0;
  border-top: 1px solid var(--rule);
}
.way:first-child { border-top: 0; }
.way-n {
  width: 28px; height: 28px; border-radius: 50%;
  display: grid; place-items: center;
  background: var(--paper-deep); border: 1px solid var(--rule);
  font: 600 13px/1 var(--text); color: var(--ink-soft);
}
.way-body h3 { font-size: 19px; margin-bottom: 5px; }
.way-sub { margin: 0; color: var(--ink-soft); font-size: 15px; }
.way-out { text-align: right; font-size: 16px; line-height: 1.4; }
.way-out strong { font-family: var(--display); font-weight: 600; font-size: 18px; }
.way-out.lived strong { color: var(--immune); }
.way-out.died strong  { color: var(--tissue); }
.way-out.part strong  { color: #8a6b1f; }
.way-caveat {
  display: block; margin-top: 5px;
  font: 500 11px/1.4 var(--text);
  letter-spacing: .12em; text-transform: uppercase;
  color: var(--ink-soft);
}

/* ------------------------------------------------------- the human bridge */

.bridge {
  display: grid;
  grid-template-columns: 1fr 160px 1fr;
  gap: 26px;
  /* The two cards hold different amounts of text. Centred, their headings sat
     on different lines and read as a slip rather than a choice; stretched, they
     share a top edge and the arrow stays centred on its own. */
  align-items: stretch;
  margin: 34px auto;
}
.bridge-arrow { align-self: center; }
.bridge-side {
  background: var(--card); border: 1px solid var(--rule);
  border-radius: 16px; padding: 22px 24px;
}
.bridge-side h3 { font-size: 17px; color: var(--tissue); margin-bottom: 8px; }
.bridge-side p { margin: 0; font-size: 15.5px; }
.bridge-arrow { text-align: center; color: var(--ink-soft); }
.bridge-arrow svg { width: 110px; height: 54px; }
.bridge-arrow span {
  display: block; font: 500 11px/1.5 var(--text);
  letter-spacing: .14em; text-transform: uppercase;
}

/* --------------------------------------------------------------- the warning */

.warning {
  background: #fdeee9;
  border: 1px solid #e8bfae;
  border-left: 4px solid var(--fight);
  border-radius: 12px;
  padding: 22px 24px;
  margin: 30px 0;
}
.warning h3 { font-size: 17px; color: #9c3d1c; margin-bottom: 8px; }
.warning p { margin: 0; font-size: 15.5px; }

/* ------------------------------------------------------------------ limits */

.limits-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 20px; margin: 32px auto;
}
.limit {
  background: var(--card); border: 1px solid var(--rule);
  border-radius: 16px; padding: 20px 22px;
}
.limit h3 {
  font-size: 17px; line-height: 1.3; margin-bottom: 8px;
  /* two lines' worth, so bodies start on the same line across a row */
  min-height: 2.6em;
}
@media (max-width: 560px) { .limit h3 { min-height: 0; } }
.limit p { margin: 0; font-size: 15px; color: var(--ink-soft); }

.closing-line {
  font: 400 21px/1.55 var(--display);
  color: var(--ink);
  max-width: 30em;
  margin: 10px auto 0;
  padding-top: 26px;
  border-top: 1px solid var(--rule);
}



@media (max-width: 720px) {
  .way { grid-template-columns: 28px 1fr; }
  .way-out { grid-column: 2; text-align: left; margin-top: 6px; }
  .bridge { grid-template-columns: 1fr; }
  .bridge-arrow svg { transform: rotate(90deg); width: 70px; height: 40px; }
}

/* Reading blocks in the daylight rooms share their plates' left edge rather than
   sitting in a narrower centred column, which reads as a misalignment. The
   measure is set on the block, not on a wrapper. */
.room .placard, .room .warning, .room .closing-line, .room .specialist-note {
  max-width: var(--read);
  margin-left: 0;
  margin-right: 0;
}

.specialist-note {
  border-top: 1px solid var(--rule);
  padding-top: 18px;
  margin-top: 26px;
  font-size: 15px;
}
.specialist-note summary {
  cursor: pointer;
  font: 500 11px/1 var(--text);
  letter-spacing: .16em; text-transform: uppercase;
  color: var(--ink-soft);
  min-height: 40px; display: flex; align-items: center;
}
.specialist-note p { margin: 10px 0 0; color: var(--ink-soft); }

/* A reader arriving cold needs to know what kind of thing this is before the
   first picture: a real study, roughly how long, and where it came from. */
.dateline {
  font: 500 12px/1.6 var(--text);
  letter-spacing: .1em; text-transform: uppercase;
  color: var(--ink-soft);
  margin: 18px 0 0;
}
.dateline em { font-style: italic; text-transform: none; letter-spacing: .04em; }
.dateline a { color: var(--immune); text-underline-offset: 3px; }

/* "trained" is load-bearing and used throughout; it is defined once, here. */
.hall-define {
  max-width: 36em; margin: 18px auto 0;
  padding: 14px 18px;
  border: 1px solid rgba(232, 237, 246, .16);
  border-radius: 4px;
  font-size: 15.5px;
  color: var(--scope-soft);
}
.hall-define strong { color: #7af0da; font-weight: 600; }

/* The plate shows two groups of mice and a worm, which immediately raises "why a
   worm?". Answering it here, before the groundwork, is what stops the worm
   reading as arbitrary. */
.why-worm {
  max-width: 38em;
  margin: 40px 0 0;
  padding-top: 28px;
  border-top: 1px solid var(--rule);
}
.why-worm h2 {
  font-size: clamp(24px, 3.2vw, 32px);
  margin-bottom: 12px;
}
.why-worm p { font-size: 17.5px; }
.why-worm p:last-child { margin-bottom: 0; }

/* Text that exists only for a screen reader: descriptions that cannot live
   inside the element they describe, because role="slider" makes its own
   subtree presentational. */
.hall[tabindex]:focus { outline: none; }

.vh {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0; border: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
}