:root {
    --bc-primary: #4f46e5;
    --bc-primary-dark: #4338ca;
    --bc-accent: #06b6d4;
    --bc-surface: #ffffff;
    --bc-bg: #f1f5f9;
    --bc-text: #0f172a;
    --bc-muted: #64748b;
    --bc-radius: 0.75rem;
    --bc-shadow: 0 4px 6px -1px rgb(15 23 42 / 0.07), 0 2px 4px -2px rgb(15 23 42 / 0.05);
    --bc-shadow-lg: 0 10px 15px -3px rgb(15 23 42 / 0.08), 0 4px 6px -4px rgb(15 23 42 / 0.05);
}

body {
    background: linear-gradient(160deg, #eef2ff 0%, var(--bc-bg) 45%, #ecfeff 100%);
    color: var(--bc-text);
    min-height: 100vh;
}

.bc-navbar {
    background: rgba(255, 255, 255, 0.85) !important;
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgb(15 23 42 / 0.06);
    box-shadow: var(--bc-shadow);
}

.bc-brand {
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--bc-primary) !important;
}

.bc-brand-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    border-radius: 0.5rem;
    background: linear-gradient(135deg, var(--bc-primary), var(--bc-accent));
    color: #fff;
    font-size: 1rem;
    margin-right: 0.5rem;
    vertical-align: -0.15em;
}

main.bc-main {
    padding-top: 2rem;
    padding-bottom: 3rem;
}

.bc-page-title {
    font-weight: 700;
    letter-spacing: -0.03em;
}

.bc-card {
    border: none;
    border-radius: var(--bc-radius);
    box-shadow: var(--bc-shadow);
    transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.bc-card:hover {
    box-shadow: var(--bc-shadow-lg);
}

.bc-test-card .card-title {
    font-weight: 600;
}

.bc-stat-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.35rem 0.75rem;
    border-radius: 999px;
    font-size: 0.875rem;
    font-weight: 500;
    background: #f1f5f9;
    color: var(--bc-muted);
}

.bc-play-question {
    font-size: 1.5rem;
    font-weight: 600;
    line-height: 1.4;
    letter-spacing: -0.02em;
}

.bc-answer-box {
    background: #f8fafc;
    border-left: 4px solid var(--bc-primary);
    border-radius: 0 var(--bc-radius) var(--bc-radius) 0;
    padding: 1rem 1.25rem;
}

.bc-empty-state {
    text-align: center;
    padding: 3rem 1.5rem;
}

.bc-empty-state .bi {
    font-size: 3rem;
    color: var(--bc-primary);
    opacity: 0.5;
}

.yandex-banner {
    margin: 1rem 0;
    min-height: 90px;
    overflow: hidden;
    border-radius: var(--bc-radius);
}

.btn-primary {
    --bs-btn-bg: var(--bc-primary);
    --bs-btn-border-color: var(--bc-primary);
    --bs-btn-hover-bg: var(--bc-primary-dark);
    --bs-btn-hover-border-color: var(--bc-primary-dark);
    --bs-btn-active-bg: var(--bc-primary-dark);
    --bs-btn-active-border-color: var(--bc-primary-dark);
}

.progress-bar {
    background: linear-gradient(90deg, var(--bc-primary), var(--bc-accent));
}

.qa-item {
    animation: bc-fade-in 0.25s ease;
}

@keyframes bc-fade-in {
    from {
        opacity: 0;
        transform: translateY(6px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}