:root {
    --primary-color: #4f7cff;
    --primary-dark: #315ed8;
    --soft-bg: #f5f8ff;
    --text-color: #1f2937;
    --muted-color: #6b7280;
    --radius-lg: 24px;
}

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--text-color);
    background: #ffffff;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar-brand {
    color: var(--primary-color) !important;
    font-size: 1.4rem;
}

.hero-section {
    padding: 90px 0;
    background: linear-gradient(135deg, #eef4ff 0%, #ffffff 100%);
}

.hero-section h1 {
    line-height: 1.15;
}

.hero-card {
    background: #ffffff;
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: 0 20px 50px rgba(31, 41, 55, 0.12);
    text-align: center;
}

.sound-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    border-radius: 50%;
    background: var(--soft-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.2rem;
}

.demo-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin-top: 25px;
}

.demo-item {
    background: var(--soft-bg);
    border-radius: 18px;
    padding: 20px 10px;
    font-size: 2rem;
    font-weight: 700;
}

.demo-item span {
    display: block;
    margin-top: 8px;
    font-size: 1rem;
}

.content-section {
    padding: 80px 0;
}

.section-title {
    max-width: 760px;
    margin: 0 auto 45px;
    text-align: center;
}

.section-title h2 {
    font-weight: 800;
    margin-bottom: 15px;
}

.section-title p {
    color: var(--muted-color);
    font-size: 1.1rem;
}

.info-card,
.feature-card,
.notice-box {
    height: 100%;
    background: #ffffff;
    border-radius: var(--radius-lg);
    padding: 28px;
    box-shadow: 0 12px 35px rgba(31, 41, 55, 0.08);
}

.info-card h3 {
    font-size: 1.25rem;
    font-weight: 800;
    margin-bottom: 12px;
}

.info-card p,
.notice-box p {
    color: var(--muted-color);
    margin-bottom: 0;
}

.feature-card {
    text-align: center;
    font-weight: 700;
    min-height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.notice-box {
    background: var(--soft-bg);
    border-left: 6px solid var(--primary-color);
}

.cta-section {
    padding: 80px 0;
    background: var(--primary-color);
    color: #ffffff;
}

.cta-section p {
    max-width: 650px;
    margin: 15px auto 30px;
    font-size: 1.1rem;
}

.site-footer {
    padding: 35px 0;
    background: #111827;
    color: #ffffff;
}

.btn-primary {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-primary:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
}

@media (max-width: 768px) {
    .hero-section {
        padding: 55px 0;
        text-align: center;
    }

    .content-section {
        padding: 55px 0;
    }

    .hero-card {
        padding: 24px;
    }

    .demo-grid {
        grid-template-columns: 1fr 1fr;
    }
}