/* --- 基本設定（共通） --- */
body {
    /* 薄い水色から白へのグラデーション */
    background: linear-gradient(135deg, #e0f2fe 0%, #f9fafb 100%);
    min-height: 100vh;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    color: #1f2937;
    display: flex;
    flex-direction: column;
    align-items: center;
}

header {
    margin-top: 40px;
    margin-bottom: 20px;
    text-align: center;
}

/* ホームに戻る・アプリ紹介に戻る用のリンクスタイル */
.back-link {
    display: inline-block;
    margin-top: 10px;
    text-decoration: none;
    color: #0ea5e9;
    font-size: 0.9rem;
    font-weight: bold;
    transition: 0.2s;
}

.back-link:hover {
    text-decoration: underline;
    transform: translateX(-3px);
}

/* --- バナー広告のスタイル --- */
.ad-banner {
    width: 90%;
    max-width: 500px;
    margin: 10px auto 20px auto;
    background: white;
    border: 1px solid #e5e7eb;
    border-radius: 16px;
    overflow: hidden;
    position: relative;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.03);
    transition: transform 0.3s ease;
}

.ad-banner:hover { transform: scale(1.02); }

.ad-label {
    position: absolute;
    top: 5px;
    right: 12px;
    font-size: 10px;
    color: #9ca3af;
    letter-spacing: 1px;
    margin: 0;
}
.ad-banner a {
    text-decoration: none;
    display: block;
    padding: 20px;
    background: linear-gradient(90deg, #ffffff 0%, #f1f5f9 100%);
}

.ad-content h3 { margin: 0; font-size: 0.95rem; color: #374151; }
.ad-content p { margin: 5px 0 0 0; font-size: 0.8rem; color: #6b7280; }

/* --- セレクト画面・カード用スタイル --- */
.select-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
    width: 95%;
    max-width: 1000px;
    margin-bottom: 50px;
}

.hero {
    background-color: white;
    margin: 10px;
    padding: 40px;
    width: 100%;
    max-width: 450px;
    border-radius: 28px;
    text-align: center;
    box-sizing: border-box;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.hero:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
}

.card-icon { font-size: 4rem; margin-bottom: 10px; display: block; }

.app-icon {
    width: 100px;
    height: 100px;
    border-radius: 22px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.2s;
    object-fit: cover;
}

.app-icon:hover { transform: scale(1.05); }

h1 { font-size: 1.6rem; margin: 15px 0; color: #111827; }
p { color: #6b7280; line-height: 1.6; margin-bottom: 20px; }

/* --- アプリストア風ボタン --- */
.detail-btn {
    display: inline-block;
    background: linear-gradient(135deg, #38bdf8 0%, #0ea5e9 100%);
    color: white;
    padding: 12px 40px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: bold;
    font-size: 1rem;
    box-shadow: 0 4px 15px rgba(14, 165, 233, 0.3);
    transition: all 0.3s ease;
}
.detail-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 20px rgba(14, 165, 233, 0.4);
    filter: brightness(1.1);
}

/* --- ボカロカード・チャンネル紹介用スタイル --- */
.vocaloid-card { border-top: 6px solid #ff77bb; }

.vocaloid-card .detail-btn {
    background: linear-gradient(135deg, #ff77bb 0%, #ff4499 100%);
    box-shadow: 0 4px 15px rgba(255, 119, 187, 0.3);
}
.vocaloid-card .detail-btn:hover { box-shadow: 0 6px 20px rgba(255, 119, 187, 0.5); }

/* SNS・チャンネルボタンのレイアウト */
.channel-links {
    display: flex;
    flex-direction: column;
    gap: 12px;
    align-items: center;
    margin-top: 20px;
}

.channel-btn {
    display: block;
    width: 100%;
    max-width: 280px;
    padding: 14px;
    border-radius: 14px;
    text-decoration: none;
    font-weight: bold;
    color: white;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    text-align: center;
}

.niconico {
    background-color: #252525;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.youtube {
    background-color: #FF0000;
    box-shadow: 0 4px 12px rgba(255, 0, 0, 0.2);
}

.channel-btn:hover {
    transform: translateY(-3px);
    filter: brightness(1.1);
}

/* --- YouTube埋め込みのレスポンシブ設定 --- */
.video-container {
    position: relative;
    width: 100%;
    padding-top: 56.25%; /* 16:9 の比率を維持 */
    margin-top: 15px;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    /* 再生できない問題を回避するためのバックグラウンド */
    background: #000;
}
.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
    /* クリックを邪魔しないための設定 */
    z-index: 1;
}

/* --- 詳細ページ用スタイル --- */
.detail-box {
    text-align: left;
    background: #f9fafb;
    padding: 20px;
    border-radius: 18px;
    margin: 20px 0;
}

.feature-list { padding-left: 20px; line-height: 1.8; color: #4b5563; }

.back-button {
    display: inline-block;
    margin-top: 20px;
    text-decoration: none;
    color: #6b7280;
    font-size: 0.9rem;
    padding: 10px 20px;
    background-color: #f3f4f6;
    border-radius: 12px;
    transition: 0.2s;
}

.back-button:hover {
    background-color: #e5e7eb;
    color: #111827;
}

/* --- PC向けの調整 --- */
@media (min-width: 600px) {
    h1 { font-size: 2rem; }
    .select-container { padding: 40px; }
    .channel-links { flex-direction: row; justify-content: center; }
}

.separator { display: none; }