:root {
  --bg: #F5F6F8;
  --surface: #FFFFFF;
  --text: #15171C;
  --muted: #6B7280;
  --line: #E4E6EB;
  --accent: #4F46E5;
  --accent-ink: #FFFFFF;
  --good: #16A34A;
  --bad: #DC2626;
  --opt-0: #E5484D;
  --opt-1: #3E63DD;
  --opt-2: #D98A00;
  --opt-3: #2B9A66;
  --radius: 18px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .05), 0 6px 24px rgba(16, 24, 40, .07);
}

* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}
[hidden] { display: none !important; }
h1, h2, h3 { margin: 0; letter-spacing: -0.01em; }
p { margin: 0; }

button { font: inherit; cursor: pointer; border: 0; background: none; color: inherit; }
.btn {
  background: var(--accent); color: var(--accent-ink);
  padding: 12px 22px; border-radius: 12px; font-weight: 650; font-size: 16px;
  transition: transform .08s ease, opacity .2s ease, background .2s ease;
}
.btn:hover { filter: brightness(1.06); }
.btn:active { transform: scale(.97); }
.btn:disabled { opacity: .35; cursor: not-allowed; filter: none; transform: none; }
.btn.ghost { background: var(--surface); color: var(--text); border: 1px solid var(--line); }
.btn.big { padding: 16px 34px; font-size: 20px; border-radius: 14px; }
.btn.danger { color: var(--bad); }

input, select {
  font: inherit; color: var(--text); background: var(--surface);
  padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; width: 100%;
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: -1px; border-color: transparent; }

.card { background: var(--surface); border-radius: var(--radius); box-shadow: var(--shadow); padding: 28px; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
.eyebrow { font-size: 13px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.err { color: var(--bad); min-height: 1.4em; font-size: 15px; }

/* Answer tiles */
.opts { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.opt {
  display: flex; align-items: center; gap: 16px;
  padding: 18px 20px; border-radius: 14px; color: #fff; font-weight: 650;
  text-align: left; min-height: 84px; transition: opacity .3s ease, transform .1s ease;
}
.opt-0 { background: var(--opt-0); }
.opt-1 { background: var(--opt-1); }
.opt-2 { background: var(--opt-2); }
.opt-3 { background: var(--opt-3); }
.letter {
  flex: none; display: inline-grid; place-items: center;
  width: 40px; height: 40px; border-radius: 10px;
  background: rgba(255, 255, 255, .22); font-weight: 800;
}
.opt.dim { opacity: .28; }
.opt .mark { margin-left: auto; font-size: 26px; }

.dot-pulse { display: inline-block; width: 10px; height: 10px; border-radius: 50%; background: var(--accent); animation: pulse 1.4s ease-in-out infinite; }
@keyframes pulse { 0%, 100% { opacity: .25; transform: scale(.8); } 50% { opacity: 1; transform: scale(1.15); } }
@keyframes pop { from { opacity: 0; transform: translateY(10px) scale(.98); } to { opacity: 1; transform: none; } }
.pop { animation: pop .35s ease both; }

.progress { height: 6px; background: var(--line); border-radius: 99px; overflow: hidden; }
.progress > div { height: 100%; background: var(--accent); border-radius: 99px; transition: width .25s linear; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}