:root {
  /* Light theme — WCAG AA contrast verified against the surfaces they sit on. */
  --bg: #ffffff;
  --fg: #1a1a1a;            /* 16:1 on white */
  --muted: #595959;         /* 7:1 on white (also used for placeholders) */
  --accent: #0b5cab;        /* 5.3:1 on white; white text on it = 5.3:1 */
  --accent-fg: #ffffff;
  --border: #6b6b6b;        /* 3.8:1 on white — non-text UI boundary */
  --error: #b00020;         /* 6.4:1 on white */
  --surface: #f3f5f7;
  --focus: #0b5cab;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font: 1.05rem/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--fg);
  background: var(--bg);
}

header, main, footer { max-width: 60rem; margin: 0 auto; padding: 1rem 1.25rem; }
header { padding-top: 1.5rem; }
h1 { font-size: 1.75rem; margin: 0 0 .25rem; }
.tagline { color: var(--muted); margin: 0 0 .5rem; }
h2 { font-size: 1.3rem; margin: 1.5rem 0 .5rem; }

.visually-hidden {
  position: absolute !important; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* Skip link — visible on focus. */
.skip-link {
  position: absolute; left: .5rem; top: -3rem; background: var(--accent);
  color: var(--accent-fg); padding: .6rem 1rem; border-radius: 6px; z-index: 10;
  transition: top .15s ease;
}
.skip-link:focus { top: .5rem; }

label { display: block; font-weight: 600; margin-bottom: .25rem; }
.help { color: var(--muted); font-size: .95rem; margin: .35rem 0 .75rem; }

.input-row { display: flex; gap: .5rem; align-items: stretch; }
textarea {
  flex: 1; font: inherit; padding: .6rem .7rem; border: 2px solid var(--border);
  border-radius: 8px; resize: vertical; min-height: 3rem; color: var(--fg); background: var(--bg);
}
::placeholder { color: var(--muted); opacity: 1; }  /* 7:1 — meets 1.4.3 */

.icon-btn {
  font-size: 1.4rem; min-width: 3rem; min-height: 3rem; border: 2px solid var(--border);
  background: var(--surface); border-radius: 8px; cursor: pointer; color: var(--fg);
}
.icon-btn[aria-pressed="true"] { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }

.controls { display: flex; flex-wrap: wrap; gap: .75rem 1rem; align-items: center; margin-top: .75rem; }
.speak-toggle { display: inline-flex; align-items: center; gap: .4rem; }
.speak-toggle label, .voice-label { display: inline; font-weight: 400; margin: 0; }
/* Target size (WCAG 2.5.8): >= 24x24 hit areas. */
#speak { width: 1.5rem; height: 1.5rem; }
select { font: inherit; padding: .4rem .45rem; min-height: 2.25rem; border: 2px solid var(--border); border-radius: 6px; color: var(--fg); background: var(--bg); }

button {
  font: inherit; cursor: pointer; border-radius: 8px; padding: .55rem 1.1rem; min-height: 2.5rem;
  border: 2px solid var(--border); background: var(--surface); color: var(--fg);
}
button.primary { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); font-weight: 600; }
button[aria-disabled="true"] { opacity: .6; cursor: progress; }

/* Clear, high-contrast keyboard focus indicator (WCAG 2.4.7). */
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }

.status { color: var(--muted); min-height: 1.4rem; margin: .75rem 0 0; }
.status.busy::before { content: "\23F3 "; }  /* hourglass; decorative */
.error { color: var(--error); font-weight: 600; min-height: 1.4rem; margin: .25rem 0 0; }

.answer {
  background: var(--surface); border: 1px solid var(--border); border-radius: 10px;
  padding: 1rem 1.1rem; min-height: 3rem;
}
.answer .placeholder { color: var(--muted); margin: 0; }
.answer p { margin: 0 0 .6rem; }
.answer p:last-child { margin-bottom: 0; }

table { border-collapse: collapse; width: 100%; margin: .5rem 0 1rem; }
caption { text-align: left; font-weight: 600; padding: .4rem 0; }
th, td { border: 1px solid var(--border); padding: .4rem .55rem; text-align: left; vertical-align: top; }
thead th, tbody th[scope="row"] { background: var(--surface); }
tbody tr:nth-child(even) { background: var(--bg); filter: brightness(.985); }

audio { width: 100%; margin: .25rem 0 .5rem; }

/* ---------- Conversation mode ---------- */
.cmode { border: 1px solid var(--border); border-radius: 10px; padding: .75rem 1rem; background: var(--surface); }
.cmode h2 { margin-top: .25rem; }
.cmode-row { display: flex; flex-wrap: wrap; gap: .6rem; align-items: center; }

/* Switch (role="switch"); state shown by text + an inset marker, not color alone. */
#cmodeToggle { font-weight: 600; padding-left: 2.9rem; position: relative; }
#cmodeToggle::before {
  content: ""; position: absolute; left: .5rem; top: 50%; transform: translateY(-50%);
  width: 2rem; height: 1.1rem; border: 2px solid currentColor; border-radius: 1rem; background: transparent;
}
#cmodeToggle::after {
  content: ""; position: absolute; left: .75rem; top: 50%; transform: translateY(-50%);
  width: .7rem; height: .7rem; border-radius: 50%; background: currentColor; transition: left .15s ease;
}
#cmodeToggle[aria-checked="true"] { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }
#cmodeToggle[aria-checked="true"]::after { left: 1.7rem; }

#cmodeStop { font-weight: 600; }

.cmode-state { display: inline-flex; align-items: center; gap: .4rem; font-weight: 600; }
.cmode-state .dot { width: .8rem; height: .8rem; border-radius: 50%; background: var(--muted); border: 1px solid var(--border); }
/* Distinct, labelled states — text label is authoritative; color is supplementary. */
.cmode-state[data-state="idle"] .dot { background: var(--accent); }
.cmode-state[data-state="armed"] .dot { background: #1f9d55; }     /* green, >=3:1 */
.cmode-state[data-state="review"] .dot { background: #b8860b; }    /* amber */
.cmode-state[data-state="speaking"] .dot { background: #6f42c1; }  /* purple */
@media (prefers-reduced-motion: no-preference) {
  .cmode-state[data-state="armed"] .dot { animation: pulse 1.2s ease-in-out infinite; }
}
@keyframes pulse { 0%,100% { transform: scale(1); opacity: 1; } 50% { transform: scale(1.5); opacity: .55; } }

.settings { margin-top: .75rem; }
.settings summary { cursor: pointer; font-weight: 600; padding: .25rem 0; }
.settings-grid { display: grid; gap: .5rem 1.25rem; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); margin-top: .5rem; }
.field { margin: 0; }
.field.check { display: flex; align-items: center; gap: .5rem; }
.field.check label { display: inline; font-weight: 400; margin: 0; }
.field input[type="text"], .field select { width: 100%; }
button.subtle { background: transparent; }
.mic.armed { border-color: #1f9d55; background: #1f9d55; color: #fff; }

.dataset-actions { display: flex; gap: .5rem; margin: .25rem 0 1.5rem; flex-wrap: wrap; }
.dataset-actions button { padding: .4rem .9rem; font-size: .95rem; min-height: 2.25rem; }

footer { color: var(--muted); font-size: .9rem; border-top: 1px solid var(--border); margin-top: 1rem; }
footer a, .answer a { color: var(--accent); }

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}

@media (prefers-color-scheme: dark) {
  :root {
    /* Dark theme — contrast verified on --bg #14171a:
       fg #f1f3f5 ~15:1, muted #b8c0c8 ~9:1, accent #6db3ff ~7:1 (and as focus
       outline >=3:1), error #ff8a9b ~7:1; accent-fg #0a0d10 on #6db3ff ~7:1. */
    --bg: #14171a;
    --fg: #f1f3f5;
    --muted: #b8c0c8;
    --surface: #1f242a;
    --border: #8a93a0;
    --accent: #6db3ff;
    --accent-fg: #0a0d10;
    --error: #ff8a9b;
    --focus: #6db3ff;
  }
  tbody tr:nth-child(even) { filter: brightness(1.15); }
}