/* --- インタラクティブ背景 --- */
#interactive-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    z-index: -1; /* コンテンツの背面に配置 */
    background-image: url('../images/bg_harmony.png'); /* デフォルトの背景 */
    background-size: cover;
    background-position: center;
    opacity: 0.2;
    transition: background-image 1.5s ease-in-out, opacity 1.5s ease-in-out;
}

/* --- 再生ボタン (今回は未使用) --- */
/*
.lyrics-artwork {
    position: relative;
}

#play-pause-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 80px;
    background-color: rgba(0, 0, 0, 0.5);
    border: 2px solid #fff;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    z-index: 10;
    backdrop-filter: blur(5px);
}

#play-pause-btn::before {
    content: '';
    display: block;
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-top: 15px solid transparent;
    border-bottom: 15px solid transparent;
    border-left: 25px solid #fff;
    transform: translate(-40%, -50%);
    transition: all 0.3s ease;
}

#play-pause-btn.playing::before {
    width: 25px;
    height: 30px;
    border: none;
    border-left: 8px solid #fff;
    border-right: 8px solid #fff;
    transform: translate(-50%, -50%);
}

#play-pause-btn:hover {
    background-color: rgba(0, 242, 255, 0.5);
    border-color: #00f2ff;
}
*/

/* --- 隠しYouTubeプレーヤー (今回は未使用) --- */
#youtube-player {
    position: absolute;
    top: -9999px;
    left: -9999px;
    width: 1px;
    height: 1px;
}

/* --- 歌詞のハイライト (今回は未使用) --- */
/*
.lyrics-content span {
    transition: color 0.5s ease, text-shadow 0.5s ease;
    opacity: 0.5;
}

.lyrics-content span.current {
    color: #ffffff;
    opacity: 1;
    text-shadow: 0 0 10px #00f2ff, 0 0 20px #00f2ff;
}
*/

/* --- インタラクティブな歌詞 --- */
.interactive-lyric {
    color: #a8c8e0; /* 通常の歌詞と少し色を変える */
    cursor: pointer;
    text-decoration: underline;
    text-decoration-color: rgba(0, 242, 255, 0.5);
    text-decoration-style: dotted;
    transition: color 0.3s, text-decoration-color 0.3s;
}

.interactive-lyric:hover {
    color: #00f2ff;
    text-decoration-color: #00f2ff;
}

/* --- ポップアップ --- */
.lyric-popup {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(10, 10, 20, 0.7);
    backdrop-filter: blur(10px);
    z-index: 2000;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.4s ease, visibility 0.4s ease;
}

.lyric-popup.is-visible {
    opacity: 1;
    visibility: visible;
}

.lyric-popup-content {
    background-color: rgba(20, 20, 35, 0.9);
    padding: 40px;
    border-radius: 8px;
    max-width: 600px;
    margin: 20px;
    color: #e0e0e0;
    font-family: 'Noto Sans JP', sans-serif;
    font-size: 1.1rem;
    line-height: 1.8;
    position: relative;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transform: scale(0.9);
    transition: transform 0.4s ease;
}

.lyric-popup.is-visible .lyric-popup-content {
    transform: scale(1);
}

.lyric-popup-close {
    position: absolute;
    top: 15px;
    right: 20px;
    background: none;
    border: none;
    color: #fff;
    font-size: 2.5rem;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.3s ease;
}
.lyric-popup-close:hover {
    opacity: 1;
}