html,
        body {
            margin: 0;
            padding: 0;
            overflow: hidden;
            background: linear-gradient(to top, rgb(143, 182, 255) 0%, #00344d 100%);
            height: 100%;
        }

        canvas {
            display: block;
            background: transparent;
            /* ← canvas 自体は透過 */
        }

        #scoreInfo {
            padding: 10px;
            /* ← transitionに影響 */
            position: absolute;
            top: 90px;
            left: 20px;
            width: 400px;
            color: #333;
            font-size: 16px;
            font-family: sans-serif;
            z-index: 50;
            background-color: rgb(211, 211, 211);
            line-height: 1.4;
        }

        button {
            user-select: none;
            -webkit-user-select: none;
            -ms-user-select: none;
        }

        #bottomScoreDisplay {
            display: none;
        }

        @media (min-height: 1200px) {
            #bottomScoreDisplay {
                display: block;
            }
        }

        /* 例: 各ボタンの共通スタイル */
        .button {
            padding: 10px 20px;
            font-size: 18px;
            border: none;
            border-radius: 10px;
            color: white;
            cursor: pointer;
            z-index: 1000;
            position: absolute;
        }

        /* 各ボタンごとのカスタム設定 */
        #resetButton {
            top: 20px;
            right: 20px;
            background-color: #f77;
        }

        #navButton {
            top: 20px;
            left: 20px;
            background-color: #7af;
        }

        #navButton2 {
            top: 20px;
            left: 130px;
            background-color: #7af;
        }

        /* スコア表示 */
        #bottomScoreDisplay {
            position: absolute;
            bottom: 10px;
            left: 50%;
            transform: translateX(-50%);
            background: rgba(0, 0, 0, 0.8);
            color: #fff;
            font-weight: bold;
            font-size: 32px;
            font-family: sans-serif;
            padding: 6px 12px;
            border-radius: 12px;
            z-index: 100;
            text-align: center;
        }

        #toggleScoreInfoBtn {
            display: none;
            position: absolute;
            top: 90px;
            left: 20px;
            padding: 6px 12px;
            font-size: 20px;
            border: none;
            border-radius: 6px;
            background-color: #88c;
            color: white;
            cursor: pointer;
            z-index: 11;
        }

        #scoreDisplay {
            font-weight: bold;
            color: black;
            text-shadow:
                -1px -1px 0 white,
                1px -1px 0 white,
                -1px 1px 0 white,
                1px 1px 0 white;
            position: absolute;
            top: 100px;
            right: 50px;
            width: 300px;
            color: black;
            font-size: 18px;
            font-family: sans-serif;
            z-index: 10;
        }

        #rotateLeftBtn {
            position: absolute;
            bottom: 80px;
            left: 20px;
            padding: 15px 20px;
            font-size: 48px;
            border-radius: 50%;
            border: none;
            background: #ccc;
            z-index: 20;
            user-select: none;
        }

        #rotateRightBtn {
            position: absolute;
            bottom: 80px;
            right: 20px;
            padding: 15px 20px;
            font-size: 48px;
            border-radius: 50%;
            border: none;
            background: #ccc;
            z-index: 20;
            user-select: none;

        }

        .resetHighScore {
            margin-top: 8px;
            font-size: 14px;
            padding: 4px 8px;
            border-radius: 6px;
            border: none;
            background-color: #f55;
            color: white;
            cursor: pointer;
        }