body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: #f0f9ff;
    margin: 0;
    color: #222;
}

.container {
    max-width: 480px;
    margin: 0 auto;
    background: #ffffff;
    min-height: 100vh;
    padding: 20px;
    box-sizing: border-box;
}

header {
    text-align: center;
    padding: 30px 0;
}

.date-badge {
    display: inline-block;
    background: #e0f2fe;
    color: #0369a1;
    font-size: 0.75rem;
    font-weight: bold;
    padding: 4px 12px;
    border-radius: 50px;
    margin-bottom: 20px;
}

.brand-logo {
    font-size: 2rem;
    font-weight: 900;
    color: #00c2ff;
    letter-spacing: -0.05em;
}

h1 { font-size: 1.2rem; margin: 10px 0 5px; }
.hero-desc { font-size: 0.9rem; color: #666; font-weight: bold; }

/* カードデザイン */
.card {
    border: 1px solid #e5e7eb;
    border-radius: 16px;
    padding: 20px;
    margin-bottom: 20px;
}

.section-title {
    font-size: 1rem;
    margin: 0 0 5px;
    font-weight: bold;
}

.small-info {
    font-size: 0.8rem;
    color: #888;
    margin-bottom: 15px;
}

/* ボタン */
.btn-newt {
    display: block;
    background: #00c2ff;
    color: #fff;
    text-decoration: none;
    text-align: center;
    font-weight: bold;
    padding: 18px;
    border-radius: 12px;
    font-size: 1.1rem;
    transition: 0.2s;
}

.btn-newt:active {
    transform: scale(0.98);
    opacity: 0.9;
}

/* コピーボックス */
.copy-box {
    display: flex;
    background: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    overflow: hidden;
}

#referralCode {
    flex: 1;
    border: none;
    background: transparent;
    padding: 14px;
    font-size: 1.2rem;
    font-weight: bold;
    text-align: center;
    color: #0369a1;
    width: 50%;
    outline: none;
}

#copyBtn {
    background: #333;
    color: #fff;
    border: none;
    padding: 0 20px;
    cursor: pointer;
    font-weight: bold;
    transition: 0.2s;
}

.copy-message {
    display: none;
    color: #0ea5e9;
    font-size: 0.75rem;
    font-weight: bold;
    margin-top: 10px;
    text-align: center;
}

/* ガイド */
.guide {
    margin-top: 30px;
    background: #fdfdfd;
    padding: 10px;
}

.guide h3 {
    font-size: 1rem;
    text-align: center;
    margin-bottom: 20px;
}

.step-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.step-item {
    display: flex;
    align-items: center;
    gap: 15px;
}

.step-num {
    background: #00c2ff;
    color: #fff;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: bold;
    flex-shrink: 0;
}

.step-item p {
    font-size: 0.85rem;
    margin: 0;
    color: #444;
}

footer {
    text-align: center;
    font-size: 0.7rem;
    color: #cbd5e1;
    margin-top: 40px;
    padding-bottom: 20px;
}