*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    min-height: 100vh;
    color: #fff;
    line-height: 1.6;
}

a { text-decoration: none; color: inherit; }

/* ─── ボタン ─────────────────────────────────────────── */

.btn {
    display: inline-block;
    padding: 14px 28px;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    border: none;
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #fff;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.45);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.15);
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.25);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.22);
    transform: translateY(-2px);
}

.btn-full { width: 100%; margin-top: auto; }

/* ─── HERO ────────────────────────────────────────────── */

.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    width: 600px;
    height: 600px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.12) 0%, transparent 70%);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    pointer-events: none;
}

.hero-inner {
    position: relative;
    max-width: 600px;
    width: 100%;
}

h1.logo {
    font-size: clamp(3rem, 10vw, 5rem);
    font-weight: 800;
    letter-spacing: -1px;
    margin-bottom: 16px;
    line-height: 1;
}

.logo-kana {
    font-size: 0.85rem;
    color: #a0a0a0;
    letter-spacing: 4px;
    margin-top: -10px;
    margin-bottom: 20px;
}

h1.logo span {
    color: #38ef7d;
    text-shadow: 0 0 30px rgba(56, 239, 125, 0.5);
}

.buzz-icon {
    font-size: clamp(2.5rem, 8vw, 4rem);
    margin-bottom: 20px;
    animation: float 3s ease-in-out infinite;
    display: block;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50%       { transform: translateY(-10px); }
}

.tagline {
    font-size: clamp(1.1rem, 3vw, 1.4rem);
    font-weight: 600;
    margin-bottom: 8px;
}

.sub-tagline {
    font-size: 0.95rem;
    color: #a0a0a0;
    margin-bottom: 40px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-buttons .btn {
    min-width: 200px;
    padding: 16px 32px;
    font-size: 1.05rem;
}

/* ─── セクション共通 ──────────────────────────────────── */

section {
    padding: 80px 20px;
    max-width: 900px;
    margin: 0 auto;
}

.section-title {
    text-align: center;
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 40px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 50px;
    height: 3px;
    background: linear-gradient(135deg, #667eea, #38ef7d);
    border-radius: 2px;
    margin: 10px auto 0;
}

/* ─── 使い方カード ─────────────────────────────────────── */

.cards {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.card {
    background: rgba(255, 255, 255, 0.07);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 32px 28px;
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
    gap: 20px;
    transition: border-color 0.3s ease, transform 0.3s ease;
}

.card:hover {
    border-color: rgba(102, 126, 234, 0.4);
    transform: translateY(-4px);
}

.card h3 {
    font-size: 1.2rem;
    font-weight: 700;
}

.steps {
    list-style: none;
    counter-reset: step;
    flex: 1;
}

.steps li {
    counter-increment: step;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 10px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.07);
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.85);
}

.steps li:last-child { border-bottom: none; }

.steps li::before {
    content: counter(step);
    min-width: 26px;
    height: 26px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea, #764ba2);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    flex-shrink: 0;
    margin-top: 1px;
}

/* ─── 注意事項 ────────────────────────────────────────── */

.notes-card {
    background: rgba(255, 255, 255, 0.07);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 32px 36px;
    backdrop-filter: blur(10px);
}

.note-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.note-list li {
    display: flex;
    gap: 12px;
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.85);
    line-height: 1.7;
}

.note-list li strong {
    color: #fff;
}

/* ─── フッター ───────────────────────────────────────── */

footer {
    text-align: center;
    padding: 30px 20px;
    color: #a0a0a0;
    font-size: 0.85rem;
    border-top: 1px solid rgba(255, 255, 255, 0.07);
}

/* ─── レスポンシブ ───────────────────────────────────── */

@media (max-width: 640px) {
    .cards {
        grid-template-columns: 1fr;
    }

    .hero-buttons .btn {
        width: 100%;
    }

    section {
        padding: 60px 20px;
    }

    .notes-card {
        padding: 24px 20px;
    }
}