:root {
    --neon-color-1: rgba(0, 255, 255, 0.8);
    --neon-color-2: rgba(255, 0, 255, 0.8);
    --neon-color-3: rgba(255, 255, 0, 0.8);
    --neon-color-4: rgba(0, 255, 0, 0.8);
    --neon-animation-duration: 6s;
}

.game-container {
    margin: 5vh auto 5vh;
    max-width: 520px;
    width: 90%;
    position: relative;
    border-radius: 15px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 0 15px var(--neon-color-1), inset 0 0 15px var(--neon-color-1);
    animation: neon-border-animation var(--neon-animation-duration) linear infinite;
    padding: 15px;
    background: rgba(13, 17, 28, 0.8);
    backdrop-filter: blur(5px);
}

#snake-game {
    background-color: #0d111c;
    width: 100%;
    border-radius: 8px;
}

.game-info {
    color: white;
    text-align: center;
    font-size: 1.2rem;
    padding-top: 10px;
    font-family: 'Poppins', sans-serif;
}

.game-controls {
    display: none; /* デスクトップでは非表示 */
    flex-direction: column;
    align-items: center;
    margin-top: 15px;
}
.game-controls div {
    display: flex;
}
.game-controls button {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--neon-color-1);
    color: white;
    font-size: 1.5rem;
    width: 60px;
    height: 60px;
    margin: 5px;
    border-radius: 10px;
    cursor: pointer;
}
.game-controls button:active {
    background: var(--neon-color-1);
}

/* タッチデバイスで操作ボタンを表示 */
@media (hover: none) and (pointer: coarse) {
    .game-controls {
        display: flex;
    }
}

/* ゲームオーバー画面 */
#game-over-screen {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(13, 17, 28, 0.95);
    color: white;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    border-radius: 15px;
    z-index: 10;
}
#game-over-screen h2 {
    font-family: 'Monoton', cursive;
    font-size: 3rem;
    color: var(--neon-color-2);
    text-shadow: 0 0 10px var(--neon-color-2);
    margin: 0;
}
#game-over-screen button {
    background: transparent;
    border: 2px solid var(--neon-color-1);
    color: var(--neon-color-1);
    padding: 10px 20px;
    font-size: 1.2rem;
    font-family: 'Poppins', sans-serif;
    border-radius: 8px;
    cursor: pointer;
    margin-top: 20px;
    transition: all 0.3s;
}
#game-over-screen button:hover {
    background: var(--neon-color-1);
    color: black;
    box-shadow: 0 0 15px var(--neon-color-1);
}

.hidden {
    display: none !important;
}

@keyframes neon-border-animation {
    0%   { box-shadow: 0 0 15px var(--neon-color-1), inset 0 0 15px var(--neon-color-1); }
    25%  { box-shadow: 0 0 15px var(--neon-color-2), inset 0 0 15px var(--neon-color-2); }
    50%  { box-shadow: 0 0 15px var(--neon-color-3), inset 0 0 15px var(--neon-color-3); }
    75%  { box-shadow: 0 0 15px var(--neon-color-4), inset 0 0 15px var(--neon-color-4); }
    100% { box-shadow: 0 0 15px var(--neon-color-1), inset 0 0 15px var(--neon-color-1); }
}