:root {
  --paper: #f5efe4;
  --card: #fffaf2;
  --ink: #1d2540;
  --ink-2: #5a6077;
  --line: #e4dccd;
  --accent: #d0583a;
  --accent-ink: #fff;
  --accent-soft: #f6dfd5;
  --echo: #3f5aa8;
  --ok: #2f7a55;
  --warn: #a5321b;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --r: 16px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #141a2b;
    --card: #1c2338;
    --ink: #f1ece2;
    --ink-2: #a8adbf;
    --line: #2d3550;
    --accent: #e9774f;
    --accent-ink: #1a1208;
    --accent-soft: #3a2a2a;
    --echo: #8aa4f0;
    --ok: #6fc79b;
    --warn: #ff8f74;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper-bg, var(--paper));
  background-attachment: fixed;
  color: var(--ink);
  font: 17px/1.5 var(--sans);
  min-height: 100vh;
  padding: env(safe-area-inset-top) 0 env(safe-area-inset-bottom);
}
main { max-width: 34rem; margin: 0 auto; padding: 16px 16px 48px; }
h1, h2, h3 { font-family: var(--display, var(--serif)); font-weight: 600; line-height: 1.2; margin: 0 0 .5em; }
h1 { font-size: 2.4rem; letter-spacing: -.01em; }
h2 { font-size: 1.6rem; }
h3 { font-size: 1.15rem; }
p { margin: 0 0 .8em; }
a { color: var(--echo); }
em { font-style: italic; color: var(--accent); }
.muted { color: var(--ink-2); }
.small { font-size: .85rem; }
.center { text-align: center; }
.loading { text-align: center; color: var(--ink-2); margin-top: 40vh; }
.eyebrow { font-size: .78rem; text-transform: uppercase; letter-spacing: .09em; color: var(--ink-2); margin-bottom: .4em; font-weight: 600; }

/* The echo mark: one circle and its offset double. */
.mark { position: relative; width: 84px; height: 64px; margin: 8px 0 20px; }
.mark span { position: absolute; top: 0; width: 64px; height: 64px; border-radius: 50%; }
.mark span:first-child { left: 0; background: var(--accent); }
.mark span:last-child { left: 20px; border: 3px solid var(--echo); }
.mini-mark { display: inline-block; width: 18px; height: 14px; position: relative; margin-right: 8px; vertical-align: -1px; }
.mini-mark::before, .mini-mark::after { content: ""; position: absolute; top: 0; width: 14px; height: 14px; border-radius: 50%; }
.mini-mark::before { left: 0; background: var(--accent); }
.mini-mark::after { left: 5px; border: 2px solid var(--echo); }

.hero { padding-top: 12vh; }
.lede { font-family: var(--serif); font-size: 1.3rem; line-height: 1.4; }

.bar { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.brand { font-family: var(--serif); font-weight: 600; font-size: 1.15rem; }
.icon-link { font-size: .9rem; text-decoration: none; color: var(--ink-2); padding: 8px 0 8px 12px; }
.back { display: inline-block; margin: 0 0 12px; text-decoration: none; color: var(--ink-2); font-size: .95rem; padding: 6px 0; }

.card {
  display: block; background: var(--card); border: var(--card-border, 1px solid var(--line)); border-radius: var(--r);
  padding: 16px 18px; margin: 0 0 14px; color: inherit; text-decoration: none; box-shadow: var(--card-shadow, none);
  -webkit-backdrop-filter: var(--card-blur, none); backdrop-filter: var(--card-blur, none);
}
.card.soft { background: transparent; border-style: dashed; }
.card.alert { background: var(--alert-bg, var(--accent)); border-color: var(--accent); color: var(--accent-ink); display: flex; justify-content: space-between; gap: 12px; align-items: center; }
.card.alert.soft { background: var(--accent-soft); color: var(--ink); border: 0; }
.card.alert span { font-size: .9rem; opacity: .85; white-space: nowrap; }
.card.danger { border-color: color-mix(in srgb, var(--warn) 40%, var(--line)); }
.row-link { display: block; padding: 8px 0 0; text-decoration: none; font-size: .95rem; }
.stat strong { font-family: var(--serif); font-size: 1.8rem; margin-right: 4px; }

/* The big button, with an echo ring that pulses gently. */
.tap-zone { padding: 28px 0 18px; }
.dv-button {
  position: relative; display: grid; place-items: center; margin: 0 auto 14px;
  width: min(36vw, 150px); aspect-ratio: 1; border-radius: 50%; border: 0; cursor: pointer;
  background: var(--dv-fill, var(--accent)); color: var(--dv-ink, var(--accent-ink)); font: 1rem/1.2 var(--display, var(--serif)); padding: 0 10px;
  box-shadow: var(--dv-glow, 0 10px 30px -12px color-mix(in srgb, var(--accent) 70%, transparent));
  -webkit-tap-highlight-color: transparent; touch-action: manipulation;
}
.dv-button strong { font-size: 1.3rem; }
.dv-button::after {
  content: ""; position: absolute; inset: -10px; border-radius: 50%;
  border: 3px solid var(--dv-ring, var(--echo)); transform: translate(12px, -5px); opacity: .9;
  animation: echo 5s ease-in-out infinite;
}
.dv-button:active, .dv-button.pressed { transform: scale(.97); }
@keyframes echo { 0%, 100% { transform: translate(12px, -5px); } 50% { transform: translate(6px, -2px); } }
@media (prefers-reduced-motion: reduce) { .dv-button::after { animation: none; } }

.forecast-line { font-family: var(--serif); font-size: 1.35rem; line-height: 1.3; margin-bottom: .6em; }
.result .forecast-line { font-size: 1.8rem; }
.big-number { font-family: var(--serif); font-size: 3rem; font-weight: 600; line-height: 1; margin: 18px 0; }
.big-number span { display: block; font: .95rem var(--sans); color: var(--ink-2); margin-top: 6px; }
progress.meter { appearance: none; -webkit-appearance: none; width: 100%; height: 8px; border: 0; border-radius: 99px; background: var(--line); overflow: hidden; margin: 2px 0 10px; }
progress.meter::-webkit-progress-bar { background: var(--line); border-radius: 99px; }
progress.meter::-webkit-progress-value { background: var(--meter, var(--accent)); border-radius: 99px; }
progress.meter::-moz-progress-bar { background: var(--meter, var(--accent)); border-radius: 99px; }

.btn {
  display: inline-block; text-align: center; font: 600 1rem var(--sans); padding: 13px 20px; border-radius: 999px;
  border: 1.5px solid var(--ink); background: transparent; color: var(--ink); text-decoration: none; cursor: pointer; margin: 6px 6px 6px 0;
}
.btn.primary { background: var(--primary-bg, var(--ink)); color: var(--primary-ink, var(--paper)); border-color: transparent; width: 100%; margin: 18px 0 6px; padding: 15px; box-shadow: var(--primary-shadow, none); }
.btn.ghost { border-color: transparent; color: var(--ink-2); width: 100%; }
.btn.warn { border-color: var(--warn); color: var(--warn); }
.btn:disabled { opacity: .5; }
.done { color: var(--ok); font-weight: 600; }

.step h3 { display: flex; align-items: center; gap: 10px; }
.n { display: inline-grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; background: var(--ink); color: var(--paper); font: 600 .85rem var(--sans); }
.steps { padding-left: 1.2em; margin: 0; }
.steps li { margin-bottom: 4px; }

/* Forms */
.q { border: 0; padding: 0; margin: 0 0 22px; min-width: 0; }
.q legend { font-weight: 600; margin-bottom: 8px; padding: 0; }
.hint { font-size: .85rem; color: var(--ink-2); margin: -4px 0 8px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip input, .dot input, .check input { position: absolute; opacity: 0; pointer-events: none; }
.chip span {
  display: inline-block; padding: 9px 14px; border-radius: 999px; border: 1.5px solid var(--line);
  background: var(--card); cursor: pointer; font-size: .95rem; line-height: 1.25;
}
.chip input:checked + span { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.chip input:focus-visible + span, .dot input:focus-visible + span, .check input:focus-visible + span::before { outline: 3px solid var(--echo); outline-offset: 2px; }
.scale-dots { display: flex; justify-content: space-between; gap: 6px; }
.dot { flex: 1; }
.dot span {
  display: grid; place-items: center; height: 44px; border-radius: 12px; border: 1.5px solid var(--line);
  background: var(--card); cursor: pointer; font-weight: 600;
}
.dot input:checked + span { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.scale-ends { display: flex; justify-content: space-between; font-size: .82rem; color: var(--ink-2); margin-top: 4px; }
.check { display: block; position: relative; padding: 10px 0 10px 38px; cursor: pointer; }
.check span::before {
  content: ""; position: absolute; left: 0; top: 10px; width: 24px; height: 24px; border-radius: 7px;
  border: 1.5px solid var(--ink-2); background: var(--card);
}
.check input:checked + span::before { background: var(--ink); border-color: var(--ink); }
.check input:checked + span::after { content: "✓"; position: absolute; left: 6px; top: 10px; color: var(--paper); font-weight: 700; }
input.text, textarea {
  width: 100%; font: inherit; color: inherit; background: var(--card); border: 1.5px solid var(--line);
  border-radius: 12px; padding: 11px 12px;
}
input.text:focus, textarea:focus { outline: 3px solid color-mix(in srgb, var(--echo) 40%, transparent); border-color: var(--echo); }

.prose p { margin-bottom: .9em; }
details summary { cursor: pointer; color: var(--echo); padding: 4px 0; }
details .prose { margin-top: 10px; }

.modal { position: fixed; inset: 0; background: rgb(10 14 26 / .55); display: grid; place-items: center; padding: 16px; z-index: 10; }
.modal .card { max-width: 30rem; max-height: 85vh; overflow: auto; }

#toast {
  position: fixed; left: 50%; bottom: calc(20px + env(safe-area-inset-bottom)); transform: translateX(-50%);
  background: var(--ink); color: var(--paper); padding: 12px 18px; border-radius: 12px; max-width: calc(100% - 32px);
  font-size: .95rem; box-shadow: 0 8px 24px rgb(0 0 0 / .25); z-index: 20;
}

/* Researcher page */
.admin table { width: 100%; border-collapse: collapse; font-size: .92rem; margin-bottom: 8px; }
.admin th, .admin td { text-align: left; padding: 6px 8px; border-bottom: 1px solid var(--line); }
.admin td.num, .admin th.num { text-align: right; font-variant-numeric: tabular-nums; }
.admin .downloads .btn { margin: 4px 4px 4px 0; }

/* v2: two experiences, sliders, quantile forecasts */
.tap-pair { display: flex; justify-content: center; gap: 36px; margin: 0 12px 14px 0; }
.tap-pair .dv-button { margin: 0; }
.dv-button.alt { background: var(--tot-fill, var(--echo)); color: var(--tot-ink, #fff); box-shadow: var(--tot-glow, 0 10px 30px -12px color-mix(in srgb, var(--echo) 70%, transparent)); }
.dv-button.alt::after { border-color: var(--tot-ring, var(--accent)); }
.def { background: transparent; }
.def h3 { margin-bottom: .3em; }
h3.section { margin-top: 28px; }
.stats { display: flex; gap: 28px; }
.stats .stat { margin: 0; }
.forecast-line.big { font-size: 1.6rem; }
.quantiles { list-style: none; padding: 0; margin: 6px 0 10px; }
.quantiles li { display: grid; grid-template-columns: 3.2rem 1fr; align-items: baseline; column-gap: 10px; margin-bottom: 8px; }
.quantiles .pct { font-family: var(--serif); font-weight: 600; font-size: 1.25rem; }
.quantiles .by { font-size: 1rem; }
.quantiles progress { grid-column: 2; height: 6px; margin: 4px 0 0; }
.slider output { display: block; font-weight: 600; margin-bottom: 4px; color: var(--ink); }
.slider:not(.set) output { color: var(--ink-2); font-weight: 400; font-style: italic; }
.slider input[type=range] { width: 100%; accent-color: var(--accent); height: 32px; }
.slider:not(.set) input[type=range] { filter: grayscale(1); opacity: .45; }

.code-card { border-color: var(--accent); }
.code { font: 600 1.6rem/1.2 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; letter-spacing: .06em; margin: 4px 0 10px; }
.code-input { font: 600 1.3rem ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; letter-spacing: .08em; text-transform: uppercase; }

/* Install help */
.install-banner { display: flex; flex-direction: column; gap: 2px; border: 1.5px dashed var(--echo); background: color-mix(in srgb, var(--echo) 10%, transparent); }
.install-banner span { font-size: .9rem; color: var(--ink-2); }
.alert-box { border: 1.5px solid var(--warn); background: color-mix(in srgb, var(--warn) 10%, var(--card)); text-align: left; }
.alert-box p { margin: 6px 0 4px; }
.hero .alert-box { margin-bottom: 20px; }

/* ---------- Palettes (set in study.js; try one with ?palette=name) ---------- */

/* NEON: midnight indigo, hot pink and electric aqua, with glow. Always dark. */
:root[data-palette=neon] {
  --paper: #0d0a22;
  --paper-bg: radial-gradient(120% 60% at 15% 0%, #2a1460 0%, transparent 60%), radial-gradient(100% 50% at 100% 30%, #07344a 0%, transparent 55%), #0d0a22;
  --card: rgb(255 255 255 / .06); --card-border: 1px solid rgb(255 255 255 / .12); --card-blur: blur(14px);
  --ink: #f7f3ff; --ink-2: #b4abd8; --line: rgb(255 255 255 / .16);
  --accent: #ff3d8b; --accent-ink: #fff; --accent-soft: rgb(255 61 139 / .16);
  --echo: #34f0d8; --ok: #5ef2a0; --warn: #ff7a7a;
  --dv-fill: linear-gradient(140deg, #ff3d8b 0%, #ff8a3d 100%); --dv-ink: #fff; --dv-ring: #34f0d8;
  --dv-glow: 0 0 0 1px rgb(255 255 255 / .1), 0 12px 50px -6px rgb(255 61 139 / .7);
  --tot-fill: linear-gradient(140deg, #34f0d8 0%, #5b5bff 100%); --tot-ink: #0d0a22; --tot-ring: #ff3d8b;
  --tot-glow: 0 0 0 1px rgb(255 255 255 / .1), 0 12px 50px -6px rgb(52 240 216 / .6);
  --primary-bg: linear-gradient(100deg, #ff3d8b, #8a5bff); --primary-ink: #fff; --primary-shadow: 0 10px 30px -10px rgb(255 61 139 / .7);
  --alert-bg: linear-gradient(100deg, #ff3d8b, #8a5bff); --meter: linear-gradient(90deg, #ff3d8b, #34f0d8);
  --display: "Avenir Next", "Futura", "Century Gothic", system-ui, sans-serif;
  --serif: "Avenir Next", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color-scheme: dark;
}
:root[data-palette=neon] .chip input:checked + span { background: var(--accent); border-color: var(--accent); color: #fff; }
:root[data-palette=neon] .n, :root[data-palette=neon] .check input:checked + span::before { background: var(--accent); border-color: var(--accent); }
:root[data-palette=neon] .check input:checked + span::after { color: #fff; }
:root[data-palette=neon] h1 { background: linear-gradient(90deg, #ff3d8b, #ffb03d 50%, #34f0d8); -webkit-background-clip: text; background-clip: text; color: transparent; }
:root[data-palette=neon] .mark span:first-child { background: linear-gradient(140deg, #ff3d8b, #ff8a3d); box-shadow: 0 0 30px rgb(255 61 139 / .6); }

/* SUNSET: warm peach, magenta and violet. Light, with a dark version. */
:root[data-palette=sunset] {
  --paper: #fff3ea;
  --paper-bg: linear-gradient(180deg, #ffe3d3 0%, #fff3ea 35%, #fff8f2 100%);
  --card: #ffffff; --card-border: 1px solid #f6dccd; --card-shadow: 0 6px 20px -12px rgb(120 40 60 / .25);
  --ink: #2a0f3d; --ink-2: #77607f; --line: #f1d5c6;
  --accent: #e8256f; --accent-ink: #fff; --accent-soft: #ffe0ea;
  --echo: #6d2cf5; --ok: #1f8a5b; --warn: #c2261b;
  --dv-fill: linear-gradient(140deg, #ff4d6d 0%, #ff9f1c 100%); --dv-ink: #fff; --dv-ring: #6d2cf5;
  --dv-glow: 0 14px 34px -10px rgb(255 77 109 / .6);
  --tot-fill: linear-gradient(140deg, #7b2ff7 0%, #3a86ff 100%); --tot-ink: #fff; --tot-ring: #ff9f1c;
  --tot-glow: 0 14px 34px -10px rgb(123 47 247 / .55);
  --primary-bg: linear-gradient(100deg, #e8256f, #6d2cf5); --primary-ink: #fff; --primary-shadow: 0 10px 24px -10px rgb(232 37 111 / .6);
  --alert-bg: linear-gradient(100deg, #e8256f, #6d2cf5); --meter: linear-gradient(90deg, #ff9f1c, #e8256f);
  --display: "Avenir Next", "Futura", "Century Gothic", system-ui, sans-serif;
  --serif: "Avenir Next", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root[data-palette=sunset] {
    --paper: #1c0d2b; --paper-bg: linear-gradient(180deg, #3a1236 0%, #1c0d2b 45%, #150a22 100%);
    --card: #2a1840; --card-border: 1px solid #3d2659; --card-shadow: none;
    --ink: #fff1f6; --ink-2: #c8b2d4; --line: #3d2659; --accent-soft: #4a1838; --ok: #5ed39a; --warn: #ff8a7a;
    color-scheme: dark;
  }
}
:root[data-palette=sunset] .chip input:checked + span { background: var(--accent); border-color: var(--accent); color: #fff; }

/* RISO: risograph print. Fluorescent orange and riso blue, black ink, hard shadows. */
:root[data-palette=riso] {
  --paper: #f3ecdc;
  --paper-bg: radial-gradient(rgb(0 0 0 / .05) 1px, transparent 1.2px) 0 0 / 6px 6px, #f3ecdc;
  --card: #fffaf0; --card-border: 2px solid #121212; --card-shadow: 4px 4px 0 #121212; --r: 6px;
  --ink: #121212; --ink-2: #4a463e; --line: #121212;
  --accent: #ff4f12; --accent-ink: #121212; --accent-soft: #ffd9c7;
  --echo: #1f45ff; --ok: #0a7d3c; --warn: #d4141f;
  --dv-fill: #ff4f12; --dv-ink: #121212; --dv-ring: #1f45ff; --dv-glow: 5px 5px 0 #121212;
  --tot-fill: #1f45ff; --tot-ink: #fffaf0; --tot-ring: #ff4f12; --tot-glow: 5px 5px 0 #121212;
  --primary-bg: #121212; --primary-ink: #fffaf0; --primary-shadow: 4px 4px 0 #ff4f12;
  --alert-bg: #ff4f12; --meter: #1f45ff;
  --display: "Arial Black", "Helvetica Neue", Impact, system-ui, sans-serif;
  --serif: "Helvetica Neue", Helvetica, Arial, system-ui, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root[data-palette=riso] {
    --paper: #161512; --paper-bg: radial-gradient(rgb(255 255 255 / .05) 1px, transparent 1.2px) 0 0 / 6px 6px, #161512;
    --card: #211f1b; --card-border: 2px solid #f3ecdc; --card-shadow: 4px 4px 0 #ff4f12;
    --ink: #f3ecdc; --ink-2: #b9b2a2; --line: #f3ecdc; --accent-soft: #3a2316;
    --dv-glow: 5px 5px 0 #f3ecdc; --tot-glow: 5px 5px 0 #f3ecdc; --primary-bg: #f3ecdc; --primary-ink: #161512;
    color-scheme: dark;
  }
}
:root[data-palette=riso] .dv-button { border: 2.5px solid var(--ink); }
:root[data-palette=riso] .dv-button::after { mix-blend-mode: multiply; border-width: 4px; }
:root[data-palette=riso] .chip span, :root[data-palette=riso] .dot span { border-width: 2px; border-color: var(--ink); }
:root[data-palette=riso] h1 { text-transform: uppercase; letter-spacing: -.02em; }
:root[data-palette=riso] .mark span:first-child { mix-blend-mode: multiply; }

:root[data-palette=riso] .dv-button, :root[data-palette=riso] .brand { font-weight: 700; }

.browser-note { font-size: .88rem; color: var(--ink-2); text-align: center; margin: 0 0 6px; }

/* The two echo rings drift out of step: different lengths, offset starts. */
.dv-button::after { animation-duration: 5s; animation-delay: -.6s; }
.dv-button.alt::after { animation-name: echo-alt; animation-duration: 6.7s; animation-delay: -2.9s; }
@keyframes echo-alt {
  0%, 100% { transform: translate(12px, -5px); }
  40% { transform: translate(5px, -1px); }
  70% { transform: translate(9px, -4px); }
}
/* Each ring also gets a random starting point every time the screen is drawn (set in app.js). */
.dv-button::after { animation-delay: var(--ring-delay, -.6s); }
.dv-button.alt::after { animation-delay: var(--ring-delay, -2.9s); }

/* Appearance settings */
:root[data-motion=off] .dv-button::after { animation: none !important; }
.swatches { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; margin-bottom: 8px; }
.swatch { display: flex; align-items: center; gap: 10px; padding: 10px 12px; border-radius: 12px; border: 1.5px solid var(--line);
  font: 600 .95rem var(--sans); cursor: pointer; text-align: left; }
.swatch[aria-checked=true] { outline: 3px solid var(--echo); outline-offset: 2px; }
.sw-dots { display: inline-flex; }
.sw-dots i { width: 18px; height: 18px; border-radius: 50%; display: inline-block; }
.sw-dots i + i { margin-left: -6px; }
.swatch-neon { background: #0d0a22; color: #f7f3ff; }
.swatch-neon i:first-child { background: linear-gradient(140deg, #ff3d8b, #ff8a3d); } .swatch-neon i:last-child { background: linear-gradient(140deg, #34f0d8, #5b5bff); }
.swatch-sunset { background: #fff3ea; color: #2a0f3d; }
.swatch-sunset i:first-child { background: linear-gradient(140deg, #ff4d6d, #ff9f1c); } .swatch-sunset i:last-child { background: linear-gradient(140deg, #7b2ff7, #3a86ff); }
.swatch-riso { background: #f3ecdc; color: #121212; border: 2px solid #121212; }
.swatch-riso i:first-child { background: #ff4f12; } .swatch-riso i:last-child { background: #1f45ff; }
.swatch-paper { background: #f5efe4; color: #1d2540; }
.swatch-paper i:first-child { background: #d0583a; } .swatch-paper i:last-child { background: #3f5aa8; }