:root {
  color-scheme: light;
  --bg-a: #f8fafc;
  --bg-b: #dbeafe;
  --card: rgba(255, 255, 255, 0.96);
  --text: #0f172a;
  --muted: #475569;
  --accent: #0f766e;
  --accent-strong: #115e59;
  --border: rgba(15, 23, 42, 0.08);
  --danger-bg: rgba(220, 38, 38, 0.08);
  --danger-text: #991b1b;
  --shadow: 0 28px 70px rgba(15, 23, 42, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", Arial, sans-serif;
  background:
    radial-gradient(circle at top left, rgba(15, 118, 110, 0.16), transparent 32%),
    radial-gradient(circle at bottom right, rgba(37, 99, 235, 0.16), transparent 28%),
    linear-gradient(180deg, var(--bg-a), var(--bg-b));
  color: var(--text);
}

.challenge-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.challenge-card {
  width: min(100%, 520px);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 28px;
}

.challenge-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-radius: 999px;
  padding: 8px 12px;
  background: rgba(15, 118, 110, 0.1);
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.challenge-card h1 {
  margin: 18px 0 12px;
  font-size: clamp(28px, 4vw, 36px);
  line-height: 1.05;
}

.challenge-intro,
.challenge-footer,
.challenge-noscript {
  color: var(--muted);
  line-height: 1.6;
}

.challenge-alert {
  margin: 18px 0;
  border-radius: 16px;
  padding: 12px 14px;
  background: var(--danger-bg);
  color: var(--danger-text);
  font-weight: 600;
}

.challenge-form {
  margin-top: 18px;
}

.challenge-honeypot {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.challenge-visual {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 110px;
  margin: 10px 0 8px;
}

.challenge-image {
  width: min(100%, 220px);
  height: auto;
  display: block;
}

.challenge-actions-row {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 16px;
}

.challenge-secondary,
.challenge-submit {
  appearance: none;
  border: 0;
  border-radius: 14px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: transform 120ms ease, opacity 120ms ease, background 120ms ease;
}

.challenge-secondary {
  padding: 10px 14px;
  background: rgba(15, 23, 42, 0.06);
  color: var(--text);
}

.challenge-label {
  display: block;
  margin-bottom: 8px;
  font-weight: 700;
}

.challenge-input {
  width: 100%;
  border: 1px solid rgba(15, 23, 42, 0.14);
  border-radius: 14px;
  padding: 14px 16px;
  font: inherit;
  font-size: 18px;
  background: #fff;
}

.challenge-input:focus {
  outline: 2px solid rgba(15, 118, 110, 0.24);
  outline-offset: 2px;
  border-color: rgba(15, 118, 110, 0.35);
}

.challenge-submit {
  width: 100%;
  margin-top: 16px;
  padding: 14px 16px;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #fff;
}

.challenge-submit:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.challenge-secondary:hover,
.challenge-submit:not(:disabled):hover {
  transform: translateY(-1px);
}

.challenge-expression {
  margin: 0;
  font-size: 32px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

@media (max-width: 520px) {
  .challenge-card {
    padding: 22px;
    border-radius: 20px;
  }
}