/* Bio Explorer: clean, light layout with a dark mode. Everything is drawn in code; no external assets. */
:root {
  --bg: #f4f6f1; --card: #ffffff; --ink: #1f2a1d; --ink-dim: #5a6a57; --line: #dfe5d8;
  --accent: #2f8a4b; --accent-ink: #ffffff; --accent-soft: #e3f3e6; --warn: #c0392b; --ok: #1f8a3d;
  --shadow: 0 10px 30px rgba(35, 60, 30, .12), 0 2px 6px rgba(35, 60, 30, .08);
  --dia-in: #fffdf6; --dia-out: #ece6d0; --label: #2a2a2a; --label-halo: rgba(255, 253, 246, .92);
  --radius: 16px;
}
[data-theme='dark'] {
  --bg: #12170f; --card: #1b2217; --ink: #e8efe4; --ink-dim: #a3b39f; --line: #2d3828;
  --accent: #5fcf80; --accent-ink: #0f1a0f; --accent-soft: #233426; --warn: #ff8f80; --ok: #6fe08f;
  --shadow: 0 10px 30px rgba(0, 0, 0, .5), 0 2px 6px rgba(0, 0, 0, .4);
  --dia-in: #2a3224; --dia-out: #151b12; --label: #f1f5ee; --label-halo: rgba(20, 26, 17, .9);
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body { background: var(--bg); color: var(--ink); font: 15px/1.5 'Segoe UI', system-ui, -apple-system, Roboto, Arial, sans-serif; min-height: 100vh; }
body.modal-open { overflow: hidden; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--accent); color: var(--accent-ink); padding: 8px 12px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 8px; }
button, select, input { font: inherit; color: inherit; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

/* ---------- header ---------- */
.header { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; padding: 12px 20px; background: var(--card); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 30; }
.brand { display: flex; align-items: center; gap: 10px; margin-right: 6px; }
.logo { width: 38px; height: 38px; display: grid; place-items: center; font-size: 22px; background: var(--accent-soft); border-radius: 12px; }
.brand-name { font-weight: 800; letter-spacing: .2px; line-height: 1.1; }
.brand-sub { font-size: 12px; color: var(--ink-dim); }
.topic select, .header select { padding: 8px 10px; border: 1px solid var(--line); border-radius: 10px; background: var(--card); max-width: 230px; }
.search { position: relative; flex: 1 1 180px; max-width: 320px; }
.search input { width: 100%; padding: 9px 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg); }
.results { position: absolute; top: calc(100% + 4px); left: 0; right: 0; margin: 0; padding: 4px; list-style: none; background: var(--card); border: 1px solid var(--line); border-radius: 12px; box-shadow: var(--shadow); z-index: 40; }
.results button { display: flex; justify-content: space-between; gap: 8px; width: 100%; text-align: left; padding: 8px 10px; border: 0; background: transparent; border-radius: 8px; cursor: pointer; }
.results button:hover, .results button:focus-visible { background: var(--accent-soft); }
.results span { color: var(--ink-dim); font-size: 13px; }
.results .none { padding: 8px 10px; color: var(--ink-dim); }
.progress { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--ink-dim); }
.progress .bar { width: 80px; height: 8px; border-radius: 99px; background: var(--line); overflow: hidden; }
.progress .fill { height: 100%; background: var(--accent); transition: width .4s; }
.seg { display: inline-flex; padding: 3px; border-radius: 10px; background: var(--bg); border: 1px solid var(--line); gap: 2px; }
.seg button { border: 0; background: transparent; padding: 5px 10px; border-radius: 7px; cursor: pointer; font-weight: 600; color: var(--ink-dim); }
.seg button.on { background: var(--accent); color: var(--accent-ink); }
.btn { border: 1px solid var(--line); background: var(--card); padding: 8px 14px; border-radius: 10px; cursor: pointer; font-weight: 600; transition: transform .1s, box-shadow .15s, background .15s; }
.btn:hover { background: var(--accent-soft); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.big { padding: 12px 22px; font-size: 16px; }
.btn:disabled { opacity: .6; cursor: default; }
.icon-btn { width: 38px; height: 38px; border-radius: 10px; border: 1px solid var(--line); background: var(--card); cursor: pointer; font-size: 18px; }

/* ---------- tabs ---------- */
.tabs { display: flex; gap: 6px; padding: 10px 20px 0; overflow-x: auto; scrollbar-width: none; }
.tab { border: 1px solid var(--line); border-bottom: 0; background: var(--card); padding: 9px 16px; border-radius: 12px 12px 0 0; cursor: pointer; font-weight: 600; color: var(--ink-dim); white-space: nowrap; }
.tab.on { color: var(--accent-ink); background: var(--accent); border-color: var(--accent); }
.tab:disabled { opacity: .5; cursor: not-allowed; border-style: dashed; }

/* ---------- layout ---------- */
.layout { display: grid; grid-template-columns: minmax(0, 65fr) minmax(300px, 35fr); gap: 20px; padding: 16px 20px 28px; align-items: start; max-width: 1500px; margin: 0 auto; }
.stage-head h1 { margin: 0; font-size: 24px; letter-spacing: .1px; }
.stage-head p { margin: 2px 0 10px; color: var(--ink-dim); }
.diagram-card { position: relative; border-radius: var(--radius); background: var(--card); box-shadow: var(--shadow); overflow: hidden; aspect-ratio: 900 / 800; border: 1px solid var(--line); }
.diagram-card svg { display: block; width: 100%; height: 100%; touch-action: manipulation; user-select: none; -webkit-user-select: none; }
.tools { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.side { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); position: sticky; top: 86px; max-height: calc(100vh - 110px); overflow: hidden; display: flex; flex-direction: column; }
.sheet-handle { display: none; }
.mode-root { padding: 18px 20px 22px; overflow: auto; scrollbar-width: thin; }

/* ---------- diagram parts ---------- */
.bg-in { stop-color: var(--dia-in); } .bg-out { stop-color: var(--dia-out); }
.inset-title { font-size: 15px; font-weight: 700; fill: #6b5c33; }
[data-theme='dark'] .inset-title { fill: #d8c999; }
.part { cursor: pointer; transition: opacity .3s, filter .3s; outline: none; }
.part:hover { filter: brightness(1.1) saturate(1.1); }
.part:focus-visible { filter: drop-shadow(0 0 7px var(--accent)) drop-shadow(0 0 2px var(--accent)); }
.diagram.has-sel .part:not(.hl) { opacity: .26; }
.part.hl { animation: pulse 1.7s ease-in-out infinite; }
.part.flash { animation: flash .9s ease-out; }
@keyframes pulse { 0%, 100% { filter: drop-shadow(0 0 3px rgba(255, 196, 40, .9)) drop-shadow(0 0 1px #fff); } 50% { filter: drop-shadow(0 0 13px rgba(255, 196, 40, 1)) drop-shadow(0 0 4px #fff); } }
@keyframes flash { 0% { filter: drop-shadow(0 0 16px #5fe080); } 100% { filter: none; } }
.diagram.inert .part { cursor: default; }
.labels-layer .label line { stroke: var(--label); stroke-width: 1.4; }
.labels-layer .label circle { fill: var(--label); }
.labels-layer .label text { font-size: 20px; font-weight: 700; fill: var(--label); paint-order: stroke; stroke: var(--label-halo); stroke-width: 5px; stroke-linejoin: round; }
.labels-layer .label-ok line { stroke: var(--ok); } .labels-layer .label-ok circle { fill: var(--ok); } .labels-layer .label-ok text { fill: var(--ok); }
.labels-layer .label-reveal line { stroke: #d98a1a; } .labels-layer .label-reveal circle { fill: #d98a1a; } .labels-layer .label-reveal text { fill: #d98a1a; }
.bio-tip { position: fixed; z-index: 60; pointer-events: none; padding: 6px 10px; border-radius: 10px; background: #1b2217; color: #f1f5ee; box-shadow: var(--shadow); display: flex; flex-direction: column; font-size: 13.5px; line-height: 1.25; }
.bio-tip span { color: #a8d9b4; font-size: 12.5px; }
.bio-tip[hidden] { display: none; }

/* ---------- details panel ---------- */
.panel-head { position: relative; padding-bottom: 10px; border-bottom: 1px solid var(--line); margin-bottom: 8px; }
.panel-head h2 { margin: 2px 0 0; font-size: 24px; line-height: 1.2; }
.panel-head h2:focus { outline: none; }
.step { font-size: 12px; font-weight: 700; color: var(--accent); letter-spacing: .6px; }
.name-alt { font-size: 18px; color: var(--ink-dim); margin-top: 2px; }
.badges { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.badge { font-size: 12px; font-weight: 700; padding: 3px 10px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); border: 0; }
.badge.accessory { background: #fff3d6; color: #8a5a00; } [data-theme='dark'] .badge.accessory { background: #3a2f12; color: #f2c46a; }
.badge.link { cursor: pointer; border: 1px solid var(--line); background: transparent; color: var(--ink-dim); }
.sec { margin: 14px 0; }
.sec h3 { margin: 0 0 3px; font-size: 12px; letter-spacing: .7px; text-transform: uppercase; color: var(--accent); }
.sec p { margin: 0; }
.sec.fn p { font-size: 16px; font-weight: 600; }
.sec.dyk { background: var(--accent-soft); border-radius: 12px; padding: 10px 14px; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { border: 1px solid var(--line); background: var(--bg); padding: 4px 11px; border-radius: 99px; cursor: pointer; font-size: 13.5px; }
.chip:hover { background: var(--accent-soft); border-color: var(--accent); }
.chip.term { border-style: dashed; }
.chip.equation { cursor: default; background: var(--accent-soft); color: var(--accent); font-weight: 700; border-color: transparent; }
.walk { display: flex; gap: 10px; justify-content: space-between; margin-top: 18px; flex-wrap: wrap; }
.source { margin: 16px 0 0; font-size: 12px; color: var(--ink-dim); border-top: 1px solid var(--line); padding-top: 10px; }
.panel-empty { text-align: center; padding: 18px 4px 4px; }
.panel-empty h2 { margin: 8px 0 4px; } .panel-empty p { color: var(--ink-dim); margin: 0 0 14px; }
.empty-icon { font-size: 46px; }
.all-title { font-size: 12px; letter-spacing: .7px; text-transform: uppercase; color: var(--accent); margin: 14px 0 6px; }
.panel-empty .chips { justify-content: center; }
.sheet-close { display: none; position: absolute; right: -4px; top: -4px; width: 34px; height: 34px; border-radius: 50%; border: 1px solid var(--line); background: var(--bg); font-size: 20px; cursor: pointer; }

/* ---------- label / quiz modes ---------- */
.mode-card h2 { margin: 0 0 6px; font-size: 22px; }
.help { color: var(--ink-dim); margin: 0 0 10px; }
.best { color: var(--accent); font-weight: 700; margin: 0 0 10px; }
.label-status { font-weight: 700; margin: 8px 0; }
.label-msg { min-height: 24px; font-weight: 600; margin-bottom: 8px; }
.label-msg.ok { color: var(--ok); } .label-msg.bad { color: var(--warn); }
.bank { display: flex; flex-wrap: wrap; gap: 8px; padding: 12px; background: var(--bg); border: 1px dashed var(--line); border-radius: 14px; min-height: 64px; }
.label-chip { border: 1px solid var(--accent); background: var(--card); color: var(--ink); padding: 7px 14px; border-radius: 99px; font-weight: 700; cursor: grab; touch-action: none; box-shadow: 0 2px 6px rgba(0, 0, 0, .08); user-select: none; -webkit-user-select: none; }
.label-chip:active { cursor: grabbing; }
.label-chip.sel { background: var(--accent); color: var(--accent-ink); }
.label-chip.lifted { opacity: .35; }
.label-chip.shake { animation: shake .45s; border-color: var(--warn); }
@keyframes shake { 0%, 100% { transform: translateX(0); } 20% { transform: translateX(-7px); } 40% { transform: translateX(7px); } 60% { transform: translateX(-5px); } 80% { transform: translateX(5px); } }
.ghost { position: fixed; z-index: 80; transform: translate(-50%, -120%); pointer-events: none; padding: 7px 14px; border-radius: 99px; background: var(--accent); color: var(--accent-ink); font-weight: 700; box-shadow: var(--shadow); }
.qn { font-size: 12px; font-weight: 700; color: var(--accent); letter-spacing: .6px; text-transform: uppercase; }
.q { font-size: 21px; line-height: 1.3; margin: 4px 0 8px; }
.opts { display: grid; gap: 8px; margin: 10px 0; }
.opt.right { background: var(--ok); color: #fff; border-color: transparent; }
.feedback { margin: 12px 0; padding: 0; border-radius: 12px; }
.feedback.ok, .feedback.bad { padding: 10px 14px; }
.feedback.ok { background: rgba(31, 138, 61, .14); color: var(--ok); } .feedback.bad { background: rgba(192, 57, 43, .13); color: var(--warn); }
.feedback p { margin: 4px 0 0; color: var(--ink); font-weight: 400; }

/* ---------- glossary ---------- */
.glossary { position: fixed; inset: 0; z-index: 70; background: rgba(10, 16, 8, .55); display: grid; place-items: center; padding: 16px; }
.g-card { width: min(720px, 100%); max-height: 90vh; overflow: auto; background: var(--card); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.g-head { display: flex; justify-content: space-between; align-items: center; gap: 10px; }
.g-head h2 { margin: 0; }
.g-search { width: 100%; margin: 12px 0; padding: 10px 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg); }
.g-list h3 { font-size: 12px; letter-spacing: .7px; text-transform: uppercase; color: var(--accent); margin: 16px 0 4px; }
.g-item { padding: 8px 0; border-bottom: 1px solid var(--line); }
.g-item p { margin: 2px 0 0; color: var(--ink-dim); }
.g-item.focus { background: var(--accent-soft); border-radius: 10px; padding: 8px 10px; }
.g-name { background: none; border: 0; padding: 0; font-weight: 700; font-size: 16px; cursor: pointer; color: var(--ink); text-align: left; }
.g-name.static { cursor: default; display: block; }
.g-name:hover:not(.static) { color: var(--accent); }
.g-alt { margin-left: 10px; font-weight: 400; color: var(--ink-dim); font-size: 14px; }

/* ---------- phones and tablets: the panel becomes a bottom sheet ---------- */
@media (max-width: 920px) {
  .layout { grid-template-columns: 1fr; padding: 12px 12px 90px; }
  .header { padding: 10px 12px; position: static; }
  .brand-sub, .progress .bar { display: none; }
  .tabs { padding: 8px 12px 0; }
  .side { position: fixed; left: 0; right: 0; bottom: 0; top: auto; max-height: 44vh; border-radius: 20px 20px 0 0; transform: translateY(105%); transition: transform .32s cubic-bezier(.2, .8, .2, 1); z-index: 50; border-bottom: 0; }
  .side.open { transform: none; }
  .sheet-handle { display: block; width: 44px; height: 5px; border-radius: 99px; background: var(--line); margin: 8px auto 0; }
  .sheet-close { display: block; }
  body.sheet-open .layout { padding-bottom: 48vh; }   /* room to scroll the diagram clear of the sheet */
  .stage { scroll-margin-top: 8px; }
  .diagram-card { aspect-ratio: 900 / 800; }
  .stage-head h1 { font-size: 20px; }
}
@media (prefers-reduced-motion: reduce) { .part.hl, .part.flash, .label-chip.shake { animation: none; } .side { transition: none; } .part { transition: none; } }

/* ---------- print: just the labelled diagram ---------- */
@media print {
  .header, .tabs, .tools, .side, .skip, .bio-tip { display: none !important; }
  body { background: #fff; color: #000; }
  .layout { display: block; padding: 0; }
  .diagram-card { box-shadow: none; border: 0; max-width: 700px; margin: 0 auto; }
  .diagram.has-sel .part:not(.hl) { opacity: 1; } .part.hl { animation: none; }
}

/* ---------- Layers mode: peeled whorls slide away ---------- */
.part[data-layer], .inset[data-layer] { transition: opacity .55s ease, transform .7s cubic-bezier(.3, .7, .2, 1), filter .3s; }
.diagram [data-layer].peeled { opacity: 0; transform: translate(var(--dx, 0px), var(--dy, 0px)); pointer-events: none; }
.diagram.view-in { animation: viewIn .55s ease-out; }
@keyframes viewIn { from { opacity: 0; transform: scale(.985); } to { opacity: 1; transform: none; } }
.note { font-size: 17px; font-style: italic; fill: #7a6a45; }
[data-theme='dark'] .note { fill: #c9b98a; }
.layer-range { width: 100%; accent-color: var(--accent); }
.layer-slider { display: grid; grid-template-columns: auto 1fr auto; gap: 10px; align-items: center; margin: 12px 0 6px; font-size: 13px; color: var(--ink-dim); }
.layer-order { margin: 8px 0; padding: 8px 12px; border-radius: 10px; background: var(--accent-soft); font-size: 14px; }
.layer-title { margin: 4px 0; font-size: 20px; }
.layer-body { margin: 10px 0; padding: 12px 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--bg); }
.layer-body p { margin: 4px 0 8px; }
.help.left { margin: 6px 0 0; font-size: 13px; }
.whorl-list { list-style: none; margin: 10px 0; padding: 0; display: grid; gap: 6px; }
.whorl-list button { width: 100%; display: flex; align-items: center; gap: 10px; padding: 8px 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--card); cursor: pointer; text-align: left; }
.whorl-list button:hover { border-color: var(--accent); }
.whorl-list .gone button { opacity: .55; text-decoration: line-through; }
.whorl-list .dot { width: 18px; text-align: center; color: var(--accent); }
.whorl-list .gone .dot { color: var(--warn); }
.whorl-list .wname { font-weight: 700; flex: 1; }
.walk.wrap { flex-wrap: wrap; justify-content: flex-start; margin-top: 10px; }

/* ---------- Cross-section mode ---------- */
.view-tabs { display: grid; gap: 6px; margin: 8px 0; }
.view-tab { display: flex; align-items: center; gap: 10px; padding: 9px 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--card); cursor: pointer; font-weight: 700; text-align: left; }
.view-tab .num { width: 24px; height: 24px; display: grid; place-items: center; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font-size: 13px; }
.view-tab.on { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.view-tab.on .num { background: rgba(255, 255, 255, .25); color: inherit; }
.view-desc { margin: 8px 0 12px; }
.mini { margin: 10px 0 6px; font-size: 12px; letter-spacing: .7px; text-transform: uppercase; color: var(--accent); }
.chip.on { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.chip.hidden-part { cursor: help; opacity: .55; border-style: dashed; }
.view-details { margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--line); }
.cutline { position: absolute; left: 50%; top: 0; width: 4px; height: 100%; margin-left: -2px; background: linear-gradient(#fff, rgba(255, 255, 255, 0)); box-shadow: 0 0 14px 4px rgba(255, 255, 255, .85), 0 0 2px 1px #d33; transform-origin: top; animation: cut .65s ease-in forwards; pointer-events: none; z-index: 3; }
@keyframes cut { from { transform: scaleY(0); opacity: 1; } to { transform: scaleY(1); opacity: .9; } }
@media (prefers-reduced-motion: reduce) { .diagram.view-in, .cutline { animation: none; } .diagram [data-layer].peeled, .part[data-layer] { transition: opacity .2s; } }

/* ---------- Processes: overlay animation ---------- */
.overlay { pointer-events: none; }
.ov { opacity: 0; transform: translate(var(--tx, 0px), var(--ty, 0px)) scale(var(--sc, 1)); transform-box: fill-box; transform-origin: center; transition: opacity .6s ease var(--delay, 0s), transform 1.6s cubic-bezier(.45, .1, .25, 1) var(--delay, 0s); pointer-events: none; }
.ov.on { opacity: 1; }
.ov .draw { stroke-dasharray: 1; stroke-dashoffset: 1; transition: stroke-dashoffset 1.6s ease-in-out var(--delay, 0s); }
.ov.on .draw { stroke-dashoffset: 0; }
.ov-text { font-size: 19px; font-weight: 700; fill: var(--label); paint-order: stroke; stroke: var(--label-halo); stroke-width: 5px; stroke-linejoin: round; }
.bee .wing { transform-box: fill-box; transform-origin: 50% 100%; animation: flap .14s ease-in-out infinite alternate; }
.bee .wing2 { animation-delay: .07s; }
@keyframes flap { from { transform: rotate(-14deg) scaleY(1); } to { transform: rotate(10deg) scaleY(.55); } }
.diagram .faded { opacity: 0 !important; transition: opacity .7s; pointer-events: none; }
.proc-list { display: grid; gap: 10px; margin-top: 8px; }
.proc-card { display: flex; gap: 12px; align-items: flex-start; text-align: left; padding: 12px 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--card); cursor: pointer; }
.proc-card:hover { border-color: var(--accent); background: var(--accent-soft); }
.proc-card .num { width: 30px; height: 30px; flex: none; display: grid; place-items: center; border-radius: 50%; background: var(--accent); color: var(--accent-ink); font-weight: 800; }
.proc-card .ptxt { display: grid; gap: 3px; }
.proc-card .ptxt span { color: var(--ink-dim); font-size: 14px; }
.proc-card em { color: var(--accent); font-style: normal; font-size: 12px; font-weight: 700; }
.proc-top { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.proc-top h2 { margin: 0; font-size: 20px; }
.btn.small { padding: 5px 10px; font-size: 13px; }
.dots { display: flex; gap: 6px; flex-wrap: wrap; margin: 8px 0; }
.dot { width: 30px; height: 30px; border-radius: 50%; border: 1px solid var(--line); background: var(--card); cursor: pointer; font-weight: 700; color: var(--ink-dim); }
.dot.done { background: var(--accent-soft); color: var(--accent); }
.dot.on { background: var(--accent); color: var(--accent-ink); border-color: transparent; transform: scale(1.12); }
.proc-caption { margin: 10px 0; padding: 12px 14px; border-radius: 14px; background: var(--bg); border: 1px solid var(--line); }
.proc-caption h3 { margin: 0 0 4px; font-size: 18px; }
.proc-caption p { margin: 0; }
.restart { margin-top: 8px; }
.help.done { color: var(--accent); font-weight: 600; margin-top: 10px; }
@media (prefers-reduced-motion: reduce) { .ov, .ov .draw { transition: opacity .2s; } .bee .wing { animation: none; } }

/* ---------- Human heart topic: blood flow, valves, beating chambers ---------- */
.flow { fill: none; stroke-linecap: round; stroke-dasharray: 1 17; animation: flow 1s linear infinite; }
.flow.blue { stroke: #cfdcff; } .flow.red { stroke: #ffe1dc; }
@keyframes flow { to { stroke-dashoffset: -36; } }
.lf { transition: transform .5s cubic-bezier(.4, .1, .2, 1); }
.part.st-open .lf.av { transform: rotate(40deg); }
.part.st-open .lf.sl { transform: rotate(-44deg); }
.part.st-beat { animation: beat .8s ease-in-out infinite; transform-box: fill-box; transform-origin: center; }
@keyframes beat { 0%, 100% { transform: scale(1); } 45% { transform: scale(.9); } }
.blk { font-size: 17px; font-weight: 700; fill: #6b5530; }
[data-theme='dark'] .blk { fill: #4a3a1c; }
.ov-text.big { font-size: 56px; letter-spacing: 4px; fill: #c0392b; stroke-width: 8px; }
.badge.tag-blue { background: #dfe7ff; color: #2b44a1; } .badge.tag-red { background: #ffe0dc; color: #b0261d; }
[data-theme='dark'] .badge.tag-blue { background: #26325e; color: #aebfff; } [data-theme='dark'] .badge.tag-red { background: #4a2420; color: #ffb4aa; }
@media (prefers-reduced-motion: reduce) { .flow { animation: none; stroke-dasharray: 6 10; } .part.st-beat { animation: none; } }

/* ---------- Plant cell vs animal cell ---------- */
.cell-title { font-size: 30px; font-weight: 800; fill: var(--label); paint-order: stroke; stroke: var(--label-halo); stroke-width: 6px; }
.ov-text.big2 { font-size: 30px; font-weight: 800; fill: #2a6a3a; stroke-width: 7px; }
.ov-text.big2.animalc { fill: #b5451a; } .ov-text.big2.plantc { fill: #2f7a2a; }
[data-theme='dark'] .ov-text.big2 { fill: #8fe0a0; } [data-theme='dark'] .ov-text.big2.animalc { fill: #ffb08a; }
.badge.tag-plant { background: #dff3d6; color: #2a6a1f; } .badge.tag-animal { background: #ffe6d4; color: #a3430f; }
[data-theme='dark'] .badge.tag-plant { background: #1f3a1d; color: #a8e89a; } [data-theme='dark'] .badge.tag-animal { background: #4a2a18; color: #ffc4a0; }

/* ---------- Nephron ---------- */
.flow.blood { stroke: #ffd6dc; } .flow.filtrate { stroke: #fff3b8; } .flow.urine { stroke: #ffe14d; }
.zone { font-size: 22px; font-weight: 800; letter-spacing: 3px; fill: rgba(90, 30, 25, .45); }
.note2 { font-size: 15px; font-style: italic; fill: #5a3a2a; paint-order: stroke; stroke: rgba(255, 255, 255, .6); stroke-width: 4px; }
[data-theme='dark'] .note2 { fill: #f3d9cf; stroke: rgba(30, 20, 18, .7); }
.ov-text.small { font-size: 18px; stroke-width: 5px; }
.slowdot { transition: opacity .5s ease var(--delay, 0s), transform 2.4s ease-in-out var(--delay, 0s) !important; }
.badge.tag-red { background: #ffe0dc; color: #b0261d; } .badge.tag-tube { background: #fff0c4; color: #7a5a08; } .badge.tag-corp { background: #e6dcff; color: #4a2f8a; }
[data-theme='dark'] .badge.tag-tube { background: #4a3d12; color: #f3d98b; } [data-theme='dark'] .badge.tag-corp { background: #35295a; color: #cdbbff; }

/* ---------- Neuron and reflex arc ---------- */
.flow.impulse { stroke: #fff3a0; } .flow.brain { stroke: #cfe0ff; }
.small-note { font-size: 13px; font-style: italic; fill: #6b5a4a; }
.ov.pulsey.on circle, .ov.pulsey.on path { animation: glowpulse .9s ease-in-out infinite alternate; }
@keyframes glowpulse { from { opacity: .45; } to { opacity: 1; } }
.badge.tag-neuron { background: #e8e0ff; color: #3f2f8a; } .badge.tag-arc { background: #ffe7d2; color: #9a4a0a; }
[data-theme='dark'] .badge.tag-neuron { background: #2f2858; color: #cdbbff; } [data-theme='dark'] .badge.tag-arc { background: #4a2e18; color: #ffcf9f; }
@media (prefers-reduced-motion: reduce) { .ov.pulsey.on circle, .ov.pulsey.on path { animation: none; } }

.back-home { text-decoration: none; color: var(--ink); white-space: nowrap; }

/* ---------- Human eye: rays and states ---------- */
.flow.ray { stroke: #ffe14d; }
.note3 { font-size: 15px; font-style: italic; fill: #6b5a4a; paint-order: stroke; stroke: rgba(255, 255, 255, .6); stroke-width: 4px; }
[data-theme='dark'] .note3 { fill: #e8d9c4; stroke: rgba(30, 24, 18, .7); }
.iris-up, .iris-low, .pupil-gap, .lens-shape, .cil-up, .cil-low, .sl-up, .sl-low { transition: transform .9s cubic-bezier(.4, .1, .2, 1), opacity .9s; transform-box: fill-box; transform-origin: center; }
.part.st-bright .iris-up { transform: translateY(26px); } .part.st-bright .iris-low { transform: translateY(-26px); }
.part.st-dim .iris-up { transform: translateY(-14px); } .part.st-dim .iris-low { transform: translateY(14px); }
.part.st-bright .pupil-gap { transform: scaleY(.28); } .part.st-dim .pupil-gap { transform: scaleY(1.5); }
.part.st-thick .lens-shape { transform: scale(1.5, 1.04); } .part.st-thin .lens-shape { transform: scale(.78, 1); }
.part.st-contract .cil-up { transform: translateY(14px) scaleY(.82); } .part.st-contract .cil-low { transform: translateY(-14px) scaleY(.82); }
.part.st-slack .sl-up, .part.st-slack .sl-low { opacity: .45; }
.badge.tag-front { background: #dff1fa; color: #1f5f86; } .badge.tag-back { background: #ffe3da; color: #8a3a22; } .badge.tag-fluid { background: #e3f4e3; color: #2a6a2a; }
[data-theme='dark'] .badge.tag-front { background: #1f3a4a; color: #a8dcf5; } [data-theme='dark'] .badge.tag-back { background: #4a2a22; color: #ffc4b0; } [data-theme='dark'] .badge.tag-fluid { background: #24401f; color: #b4e8a8; }