:root {
    --page-bg: #f6f7fb;
    --ink: #18212f;
    --muted: #667085;
}

body {
    min-height: 100vh;
    color: var(--ink);
    background:
        radial-gradient(circle at top left, rgba(13, 110, 253, 0.14), transparent 32rem),
        linear-gradient(180deg, #ffffff 0%, var(--page-bg) 42%);
}

.app-shell {
    width: min(100%, 900px);
    min-height: 100vh;
    margin: 0 auto;
    padding: 2rem 1rem;
    display: grid;
    align-items: center;
}

.challenge-panel {
    width: 100%;
}

.eyebrow {
    color: var(--muted);
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0;
    text-transform: uppercase;
}

.challenge-card {
    border: 0;
    border-radius: 8px;
    box-shadow: 0 24px 80px rgba(24, 33, 47, 0.12);
}

.question-text {
    min-height: 5rem;
    font-size: clamp(1.35rem, 3vw, 2rem);
    font-weight: 700;
    line-height: 1.25;
}

.options-grid {
    display: grid;
    gap: 0.85rem;
    grid-template-columns: 1fr;
}

.option-button {
    min-height: 4.25rem;
    padding: 1rem;
    text-align: left;
    white-space: normal;
    border-radius: 8px;
    font-weight: 700;
}

.option-letter {
    display: inline-grid;
    width: 2rem;
    height: 2rem;
    margin-right: 0.65rem;
    place-items: center;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.28);
}

@media (min-width: 768px) {
    .app-shell {
        padding: 3rem 1.5rem;
    }

    .options-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}