:root {
  color-scheme: light;
  --page: #f5f5f1;
  --surface: #ffffff;
  --ink: #202b28;
  --muted: #58635e;
  --line: #dce1da;
  --accent: #245c4c;
  --accent-hover: #194736;
  --soft: #edf2ed;
  --danger: #8c3028;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
body { margin: 0; background: var(--page); color: var(--ink); line-height: 1.55; }
a { color: var(--accent); text-underline-offset: 3px; }
button, select { font: inherit; }
button, select, a { -webkit-tap-highlight-color: transparent; }
button, select { cursor: pointer; }
button:disabled { cursor: default; opacity: 0.45; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
.page { width: min(1160px, 100%); padding: 0 32px; margin: 0 auto; }
.masthead { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px; padding: 28px 0; border-bottom: 1px solid var(--line); }
.study-name { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 600; font-size: 0.94rem; }
.brand-mark { display: grid; place-items: center; width: 32px; height: 32px; border-radius: 9px; background: var(--accent); color: #ffffff; font-size: 0.85rem; letter-spacing: -0.05em; }
.preview-label, .placeholder-label { color: var(--accent); background: var(--soft); border-radius: 6px; padding: 5px 9px; font-size: 0.75rem; font-weight: 600; }
.intro { padding: 44px 0 32px; max-width: 760px; }
.eyebrow { margin: 0 0 6px; color: var(--muted); font-size: 0.72rem; font-weight: 650; letter-spacing: 0.1em; text-transform: uppercase; }
h1 { margin: 0 0 14px; font-weight: 550; font-size: clamp(2.35rem, 5vw, 3.6rem); line-height: 1.12; letter-spacing: -0.045em; }
.intro-text { max-width: 660px; margin: 0; color: var(--muted); font-size: 0.98rem; }
h2 { margin: 0; font-size: 1.5rem; line-height: 1.3; font-weight: 600; letter-spacing: -0.025em; }
h3 { margin: 0; font-size: 1rem; font-weight: 600; }
.workspace { display: grid; grid-template-columns: minmax(320px, 0.94fr) minmax(400px, 1.16fr); align-items: start; gap: 24px; }
.listening-panel, .questionnaire-panel { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; min-width: 0; }
.listening-panel { padding: 25px; position: sticky; top: 24px; }
.panel-heading { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px; }
.pair-counter { margin: 0; color: var(--muted); font-size: 0.73rem; font-variant-numeric: tabular-nums; }
.pair-picker { margin: 22px 0; }
.pair-picker label { display: block; margin-bottom: 7px; font-size: 0.83rem; color: var(--muted); }
select { display: block; width: 100%; min-width: 0; padding: 10px 12px; min-height: 45px; color: var(--ink); background: var(--surface); border: 1px solid #bac5bc; border-radius: 7px; }
.prompt { margin-bottom: 20px; padding: 15px 16px; background: var(--soft); border-radius: 8px; overflow-wrap: anywhere; }
.prompt p:last-child { margin: 4px 0 0; font-size: 0.94rem; }
.audio-card { margin-top: 16px; padding: 17px; border: 1px solid var(--line); border-radius: 10px; }
.audio-heading { display: flex; align-items: center; gap: 9px; margin-bottom: 12px; }
.audio-badge { display: grid; place-items: center; width: 29px; height: 29px; flex-shrink: 0; border-radius: 7px; background: var(--soft); color: var(--ink); font-weight: 600; font-size: 0.8rem; }
.clip-label { margin-left: auto; font-size: 0.7rem; color: var(--muted); white-space: nowrap; }
audio { display: block; width: 100%; max-width: 100%; min-width: 0; height: 42px; }
.audio-bottom { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; margin-top: 10px; }
.replay-button { min-height: 35px; padding: 4px 0; background: transparent; border: 0; color: var(--accent); font-size: 0.8rem; font-weight: 600; }
.replay-button:not(:disabled):hover { text-decoration: underline; text-underline-offset: 3px; }
.playback-note { font-size: 0.69rem; color: var(--muted); }
.audio-error { margin: 10px 0 0; color: var(--danger); font-size: 0.8rem; }
.pair-navigation { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 24px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 10px 14px; border-radius: 7px; min-height: 44px; font-size: 0.84rem; font-weight: 600; }
.button-primary { color: #ffffff; background: var(--accent); border: 1px solid var(--accent); }
.button-primary:not(:disabled):hover { background: var(--accent-hover); }
.button-secondary { background: var(--surface); color: var(--ink); border: 1px solid #bac5bc; }
.button-secondary:not(:disabled):hover { background: var(--soft); }
.alignment-note { margin: 17px 0 0; color: var(--muted); font-size: 0.77rem; }
.section-link { display: inline-block; margin-top: 14px; font-size: 0.8rem; font-weight: 500; }
.questionnaire-panel { overflow: hidden; scroll-margin-top: 20px; }
.questionnaire-heading { padding: 25px; border-bottom: 1px solid var(--line); display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.questionnaire-heading h2 { font-size: 1.2rem; }
.return-link { display: none; margin-top: 0; }
.questionnaire-placeholder { display: flex; flex-direction: column; align-items: flex-start; justify-content: center; min-height: 526px; padding: 42px; }
.questionnaire-placeholder h3 { margin-top: 24px; font-size: 1.6rem; line-height: 1.25; letter-spacing: -0.03em; font-weight: 550; }
.questionnaire-placeholder p { margin: 14px 0 0; max-width: 350px; font-size: 0.93rem; color: var(--muted); }
.questionnaire-placeholder .placeholder-detail { margin-top: 32px; font-size: 0.77rem; }
iframe { width: 100%; display: block; border: 0; min-height: 600px; background: var(--surface); }
.form-fallback { margin: 0; padding: 16px 25px 24px; font-size: 0.8rem; color: var(--muted); }
footer { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 20px; padding: 28px 0 32px; color: var(--muted); font-size: 0.73rem; }
footer p { margin: 0; }
.skip-link { position: absolute; top: 10px; left: 10px; transform: translateY(-160%); padding: 8px 12px; background: var(--surface); z-index: 2; }
.skip-link:focus { transform: none; }
.error-banner { padding: 14px 18px; background: #fff2ed; border: 1px solid #edc5ba; border-radius: 8px; color: var(--danger); }
@media (max-width: 850px) {
  .workspace { grid-template-columns: minmax(0, 1fr); }
  .listening-panel { position: static; }
  .questionnaire-placeholder { min-height: 300px; }
  .return-link { display: inline-block; }
}
@media (max-width: 480px) {
  .page { padding: 0 16px; }
  .masthead { padding: 22px 0; gap: 12px; }
  .intro { padding: 32px 0 26px; }
  .listening-panel, .questionnaire-heading { padding: 20px; }
  .audio-card { padding: 13px; }
  .clip-label { display: none; }
  .questionnaire-placeholder { padding: 28px 22px; }
  .questionnaire-heading { flex-wrap: wrap; }
  .form-fallback { padding: 16px 20px 20px; }
}
@media (pointer: coarse) { .replay-button, .section-link { min-height: 44px; display: inline-flex; align-items: center; } }
@media (prefers-reduced-motion: no-preference) { .button { transition: background-color 120ms ease; } }