/* --- アニメーション定義 --- */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* --- 基本設定 --- */
body {
    background: linear-gradient(135deg, #2c3e50, #4ca1af);
    color: #fff;
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    margin: 0;
    padding-top: 80px; /* 固定ヘッダー分のスペースを確保 */
    background-attachment: fixed; /* 背景を固定 */
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 20px;
}

/* --- ヘッダー & ナビゲーション --- */
.main-header {
    background: rgba(44, 62, 80, 0.5); /* 半透明の背景 */
    backdrop-filter: blur(10px); /* ぼかし効果 */
    -webkit-backdrop-filter: blur(10px);
    padding: 15px 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    position: fixed; /* 画面上部に固定 */
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
}

.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.server-logo {
    font-size: 1.5rem;
    font-weight: bold;
    text-decoration: none;
    color: #fff;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    margin: 0 15px;
    font-size: 1rem;
    transition: color 0.3s ease;
}

.nav-links a:hover, .nav-links a.active {
    color: #fff;
}


/* --- メインコンテンツ --- */
.main-content {
    animation: fadeIn 0.8s ease-out;
}

/* --- カードスタイル (グラスモーフィズム) --- */
.card {
    background: rgba(255, 255, 255, 0.1);
    padding: 30px 40px;
    margin-bottom: 30px;
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.card h2, .card h3 {
    margin-top: 0;
    letter-spacing: 1px;
}

.card p, .card li {
    font-size: 1.1em;
    opacity: 0.9;
    line-height: 1.7;
}

/* --- ページタイトル --- */
.page-title {
    font-size: 3em;
    margin-bottom: 40px;
    text-align: center;
    letter-spacing: 2px;
    font-weight: bold;
}

/* --- ボタン --- */
.btn {
    display: inline-block;
    background: #4ca1af;
    color: #fff;
    padding: 15px 30px;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1.1rem;
}

.btn:hover {
    background: #5dc1d0;
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.3);
}


/* --- ヒーローセクション (トップページ用) --- */
.hero-section {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: calc(100vh - 80px - 77px); /* 100vh - ヘッダー高 - フッター高 */
    text-align: center;
}

.hero-section h1 {
    font-size: 3.5em;
    margin-bottom: 15px;
    letter-spacing: 2px;
}

.hero-section p {
    font-size: 1.3em;
    margin-bottom: 30px;
    opacity: 0.9;
    max-width: 600px;
}

/* --- ルールリストのスタイル調整 --- */
.rules-list {
    list-style-type: none;
    padding-left: 0;
}
.rules-list li {
    padding: 10px 0;
    border-bottom: 1px solid rgba(255,255,255,0.2);
}
.rules-list li:last-child {
    border-bottom: none;
}
.rules-list li::before {
    content: '✓';
    color: #4ca1af;
    margin-right: 15px;
    font-weight: bold;
}


/* --- フッター --- */
footer {
    background: rgba(44, 62, 80, 0.5);
    text-align: center;
    padding: 25px 0;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* --- レスポンシブ対応 --- */
@media(max-width: 768px) {
    .main-header .container {
        flex-direction: column;
    }
    .nav-links {
        margin-top: 10px;
    }
    .nav-links a {
        margin: 0 8px;
    }
    body {
        padding-top: 120px; /* スマホ時のヘッダー高 */
    }
    .hero-section {
        min-height: calc(100vh - 120px - 77px);
    }
    .page-title {
        font-size: 2.2em;
    }
    .hero-section h1 {
        font-size: 2.5em;
    }
}