:root {
    --white-primary: #ffffff;
    --white-secondary: #e8e8e8;
    --black-primary: #1a1a2e;
    --black-secondary: #16213e;
    --accent-color: #00ffff;
    --accent-glow: rgba(0, 255, 255, 0.5);
    --grid-size: 40px;
    --border-radius: 4px;
}

@keyframes glow {
    0% { box-shadow: 0 0 5px var(--accent-color), inset 0 0 5px var(--accent-color); }
    50% { box-shadow: 0 0 20px var(--accent-color), inset 0 0 10px var(--accent-color); }
    100% { box-shadow: 0 0 5px var(--accent-color), inset 0 0 5px var(--accent-color); }
}

@keyframes gridPulse {
    0% { opacity: 0.8; }
    50% { opacity: 1; }
    100% { opacity: 0.8; }
}

/* サイバー背景エフェクトのスタイル */
.cyber-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    pointer-events: none;
    opacity: 0.5;
    mix-blend-mode: screen;
}

@keyframes cyberPulse {
    0% { opacity: 0.4; }
    50% { opacity: 0.8; }
    100% { opacity: 0.4; }
}

@keyframes cyberFlicker {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

@keyframes cyberGlow {
    0% { filter: brightness(1) drop-shadow(0 0 5px var(--accent-color)); }
    50% { filter: brightness(1.5) drop-shadow(0 0 15px var(--accent-color)); }
    100% { filter: brightness(1) drop-shadow(0 0 5px var(--accent-color)); }
}

body {
    font-family: 'Orbitron', sans-serif;
    background-color: var(--black-primary);
    background-image: 
        linear-gradient(0deg, transparent 24%, 
            rgba(0, 255, 255, .05) 25%, 
            rgba(0, 255, 255, .05) 26%, 
            transparent 27%, transparent 74%, 
            rgba(0, 255, 255, .05) 75%, 
            rgba(0, 255, 255, .05) 76%, 
            transparent 77%, transparent),
        linear-gradient(90deg, transparent 24%, 
            rgba(0, 255, 255, .05) 25%, 
            rgba(0, 255, 255, .05) 26%, 
            transparent 27%, transparent 74%, 
            rgba(0, 255, 255, .05) 75%, 
            rgba(0, 255, 255, .05) 76%, 
            transparent 77%, transparent);
    background-size: 50px 50px;
    color: var(--white-primary);
    text-align: center;
    margin: 0;
    padding: 20px 20px 0 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    position: relative;
    overflow-x: hidden;
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
}

h1 {
    color: var(--white-primary);
    text-shadow: 0 0 10px var(--accent-color);
    letter-spacing: 3px;
    margin-bottom: 60px;
}

#game-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    box-sizing: border-box;
    min-height: 100vh;
}

#game-container {
    display: flex;
    justify-content: center;
    width: 100%;
    margin: 0 auto;
    padding: 20px 0;
}

#game {
    display: grid;
    gap: 2px;
    padding: 10px;
    background-color: rgba(0, 0, 0, 0.8);
    border: 2px solid #0ff;
    box-shadow: 0 0 10px #0ff;
    margin: 0 auto;
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
}

.cell {
    width: var(--grid-size);
    height: var(--grid-size);
    background-color: #ffffff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 20px;
    cursor: pointer;
    border: none;
    margin: 0;
    transition: all 0.2s ease;
    position: relative;
    border-radius: 2px;
    box-sizing: border-box;
    border: 1px solid rgba(0, 0, 0, 0.1);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
}

.cell:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 10px var(--accent-glow);
    z-index: 1;
}

.cell.open {
    background-color: #cccccc;
    color: var(--black-primary);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
    cursor: default;
    border: 1px solid rgba(0, 0, 0, 0.15);
}

body[data-current-state="black"] #game {
    background-color: rgba(0, 0, 0, 0.3);
}

body[data-current-state="black"] .cell {
    background-color: #2a2a4e;
    color: var(--white-primary);
    border: 1px solid rgba(0, 255, 255, 0.15);
    box-shadow: 0 1px 3px rgba(0, 255, 255, 0.1);
}

body[data-current-state="black"] .cell.open {
    background-color: #0a0a1a;
    color: var(--white-primary);
    border: 1px solid rgba(0, 255, 255, 0.1);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.4),
                0 0 2px rgba(0, 255, 255, 0.1);
}

.cell.open[data-adjacent="1"] { 
    color: #0066cc; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="2"] { 
    color: #008000; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="3"] { 
    color: #cc0000; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="4"] { 
    color: #000080; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="5"] { 
    color: #800000; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="6"] { 
    color: #008080; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="7"] { 
    color: #000000; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}
.cell.open[data-adjacent="8"] { 
    color: #808000; 
    text-shadow: 0 0 1px rgba(0, 0, 0, 0.3);
    font-weight: 700;
}

body[data-current-state="black"] .cell.open[data-adjacent="1"] { 
    color: #66ffff; 
    text-shadow: 0 0 4px #66ffff, 0 0 8px rgba(102, 255, 255, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="2"] { 
    color: #00ff00; 
    text-shadow: 0 0 4px #00ff00, 0 0 8px rgba(0, 255, 0, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="3"] { 
    color: #ff6666; 
    text-shadow: 0 0 4px #ff6666, 0 0 8px rgba(255, 102, 102, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="4"] { 
    color: #6666ff; 
    text-shadow: 0 0 4px #6666ff, 0 0 8px rgba(102, 102, 255, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="5"] { 
    color: #ff66b2; 
    text-shadow: 0 0 4px #ff66b2, 0 0 8px rgba(255, 102, 178, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="6"] { 
    color: #66ffcc; 
    text-shadow: 0 0 4px #66ffcc, 0 0 8px rgba(102, 255, 204, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="7"] { 
    color: #ffffff; 
    text-shadow: 0 0 4px #ffffff, 0 0 8px rgba(255, 255, 255, 0.5);
    font-weight: 700;
}
body[data-current-state="black"] .cell.open[data-adjacent="8"] { 
    color: #ffcc66; 
    text-shadow: 0 0 4px #ffcc66, 0 0 8px rgba(255, 204, 102, 0.5);
    font-weight: 700;
}

body[data-current-state="black"] .cell.open[data-adjacent] {
    text-shadow: 0 0 4px currentColor;
}

#bgm {
    display: none;
}

#game-over-screen {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -150%);
    background: rgba(0, 0, 0, 0.95) !important;
    border: 2px solid var(--accent-color) !important;
    animation: glow 2s infinite;
    backdrop-filter: blur(5px);
    border-radius: var(--border-radius);
    min-width: 300px;
    padding: 30px !important;
    box-sizing: border-box;
    z-index: 1000;
}

#game-over-screen button {
    background: transparent;
    color: var(--white-primary);
    border: 1px solid var(--accent-color);
    padding: 10px 20px;
    font-family: 'Orbitron', sans-serif;
    cursor: pointer;
    transition: all 0.3s ease;
}

#game-over-screen button:hover {
    background: var(--accent-color);
    color: var(--black-primary);
}

.cell.mine {
    background-color: #ff0000 !important;
    animation: beat 0.5s ease-in-out;
}

.cell.flagged::before {
    content: '🚩';
    font-size: 20px;
    animation: beat 0.5s ease-in-out;
}

#settings-screen {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 60vh;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
}

#settings-title {
    color: var(--accent-color);
    margin-bottom: 2rem;
    text-align: center;
    font-size: 2rem;
    text-shadow: 0 0 10px var(--accent-glow);
}

.settings-container {
    background: rgba(0, 0, 0, 0.85);
    padding: 2rem;
    border: 1px solid var(--accent-color);
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.2);
    width: 100%;
    max-width: 400px;
    margin: 0 auto;
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
    backdrop-filter: blur(5px);
}

.setting-group {
    margin-bottom: 1.5rem;
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: 1rem;
    align-items: center;
    text-align: left;
}

.setting-group label {
    color: var(--white-primary);
    font-size: 0.9rem;
    letter-spacing: 1px;
    white-space: nowrap;
}

.setting-group select {
    background: rgba(0, 0, 0, 0.5);
    border: 1px solid var(--accent-color);
    color: var(--white-primary);
    padding: 0.5rem;
    width: 100%;
    font-family: 'Orbitron', sans-serif;
    cursor: pointer;
    outline: none;
    border-radius: var(--border-radius);
}

.setting-group select:focus {
    box-shadow: 0 0 10px var(--accent-glow);
}

/* Volume slider styles */
#volume-control {
    -webkit-appearance: none;
    width: 100%;
    height: 4px;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 2px;
    outline: none;
    position: relative;
}

#volume-control::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    background: var(--accent-color);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: -6px; /* センタリング調整 */
    position: relative;
    z-index: 2;
}

#volume-control::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: var(--accent-color);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    z-index: 2;
}

#volume-control::-webkit-slider-thumb:hover,
#volume-control::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: 0 0 10px var(--accent-glow);
}

#volume-control::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 2px;
    position: relative;
}

#volume-control::-moz-range-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 2px;
    position: relative;
}

/* 音量レベルを表示するバー */
#volume-control::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: var(--volume-percentage, 100%);
    background: var(--accent-color);
    border-radius: 2px;
    z-index: 1;
}

.sound-toggle {
    display: flex;
    align-items: center;
    gap: 1rem;
}

#start-game {
    background: transparent;
    color: var(--white-primary);
    border: 2px solid var(--accent-color);
    padding: 1rem 2rem;
    font-family: 'Orbitron', sans-serif;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
    width: 100%;
    letter-spacing: 2px;
    border-radius: var(--border-radius);
}

#start-game:hover {
    background: var(--accent-color);
    color: var(--black-primary);
    box-shadow: 0 0 20px var(--accent-glow);
}

.game-controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 600px;
    margin: 20px auto;
    padding: 0 20px;
    box-sizing: border-box;
}

.controls-container {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    width: 100%;
    margin-bottom: 20px;
}

.custom-audio-player {
    display: flex;
    align-items: center;
    gap: 15px;
    background: rgba(0, 0, 0, 0.8);
    padding: 15px;
    border: 1px solid var(--accent-color);
    border-radius: var(--border-radius);
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.1);
    flex: 1;
    max-width: 400px;
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
}

.audio-controls {
    display: flex;
    align-items: center;
    gap: 15px;
    width: 100%;
}

.play-pause-btn {
    background: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    transition: all 0.3s ease;
    flex-shrink: 0;
}

.play-pause-btn:hover {
    background: var(--accent-color);
    color: var(--black-primary);
    transform: scale(1.05);
    box-shadow: 0 0 15px var(--accent-glow);
}

.progress-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.time-display {
    font-family: 'Orbitron', sans-serif;
    color: var(--accent-color);
    font-size: 0.9em;
    text-align: right;
}

.progress-bar {
    width: 100%;
    height: 4px;
    background: rgba(0, 255, 255, 0.1);
    position: relative;
    border-radius: 2px;
    overflow: hidden;
    cursor: pointer;
}

.progress-bar-fill {
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    background: var(--accent-color);
    box-shadow: 0 0 10px var(--accent-color);
    transition: width 0.1s linear;
}

.reset-button {
    background: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    padding: 15px 30px;
    font-family: 'Orbitron', sans-serif;
    font-size: 1em;
    cursor: pointer;
    transition: all 0.3s ease;
    border-radius: var(--border-radius);
    text-shadow: 0 0 5px var(--accent-color);
    white-space: nowrap;
    min-width: 150px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.reset-button::before {
    content: '↺';
    font-size: 1.2em;
}

.reset-button:hover {
    background: var(--accent-color);
    color: var(--black-primary);
    transform: translateY(-2px);
    box-shadow: 0 0 20px var(--accent-glow);
}

/* モバイル対応 */
@media (max-width: 768px) {
    :root {
        --grid-size: 32px;
    }

    body {
        padding: 10px 5px;
    }

    h1 {
        font-size: 1.5rem;
        margin-bottom: 20px;
    }

    #game-screen {
        padding: 5px;
        width: 100%;
        box-sizing: border-box;
        overflow-x: hidden;
    }

    .game-controls {
        padding: 0 5px;
        width: 100%;
        box-sizing: border-box;
    }

    .controls-container {
        flex-direction: column;
        gap: 10px;
        width: 100%;
    }

    .custom-audio-player {
        width: 100%;
        max-width: none;
        box-sizing: border-box;
    }

    .reset-button {
        width: 100%;
    }

    #clear-screen, #game-over-screen {
        width: 90%;
        max-width: 320px;
        padding: 20px !important;
        box-sizing: border-box;
    }

    .settings-container {
        width: 90%;
        max-width: 320px;
        padding: 1rem;
        margin: 0 auto;
        box-sizing: border-box;
    }

    .setting-group {
        grid-template-columns: 1fr;
        gap: 0.5rem;
        width: 100%;
    }

    .setting-group select {
        width: 100%;
        box-sizing: border-box;
    }

    option[value="master"] {
        display: none;
    }
}

@media (max-width: 480px) {
    :root {
        --grid-size: 28px;
    }

    body {
        padding: 5px;
    }

    #game {
        padding: 5px;
    }

    .cell {
        font-size: 16px;
    }

    #clear-screen h2, #game-over-screen h2 {
        font-size: 1.8em;
    }

    .settings-info {
        font-size: 0.9em;
    }
}

/* 説明文の位置を調整 */
#game-screen p {
    margin-top: 40px;
}

.rules-container {
    position: static;
    transform: none;
    background-color: rgba(0, 0, 0, 0.8);
    border: 1px solid #0ff;
    padding: 15px;
    color: #fff;
    width: 100%;
    max-width: 800px;
    margin: 20px auto;
    z-index: 10;
    box-sizing: border-box;
}

.rules-title {
    color: var(--accent-color);
    font-size: 1.2em;
    margin-bottom: 15px;
    letter-spacing: 2px;
}

.rules-sections-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin: 15px 0;
}

.rules-section {
    margin: 0;
    height: 100%;
    box-sizing: border-box;
}

.rules-section h3 {
    color: var(--accent-color);
    margin: 0 0 10px 0;
    font-size: 1em;
    letter-spacing: 1px;
}

.rules-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.rules-section li {
    margin: 8px 0;
    padding-left: 20px;
    position: relative;
    line-height: 1.4;
}

.rules-section li::before {
    content: '>';
    position: absolute;
    left: 0;
    color: var(--accent-color);
}

.special-rule {
    grid-column: 1 / -1;
    margin: 15px 0 0 0;
    text-align: center;
    padding: 15px;
}

.sound-button {
    background: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    padding: 0;
}

.sound-button:hover {
    background: var(--accent-color);
    color: var(--black-primary);
    transform: scale(1.05);
}

.sound-button[data-enabled="false"] {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(0, 255, 255, 0.3);
    border-color: rgba(0, 255, 255, 0.3);
}

.sound-button[data-enabled="false"] .sound-icon {
    position: relative;
}

.sound-button[data-enabled="false"] .sound-icon::after {
    content: '❌';
    position: absolute;
    font-size: 20px;
    right: -8px;
    bottom: -8px;
    transform: scale(0.6);
}

.sound-status {
    color: var(--accent-color);
    font-size: 0.9em;
    min-width: 60px;
    text-align: left;
}

.pause-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.pause-content {
    text-align: center;
    animation: glow 2s infinite;
    padding: 30px;
    border: 2px solid var(--accent-color);
    background: rgba(0, 0, 0, 0.8);
    border-radius: var(--border-radius);
}

.pause-title {
    color: var(--accent-color);
    font-size: 2.5em;
    margin-bottom: 20px;
    text-shadow: 0 0 10px var(--accent-color);
    letter-spacing: 5px;
}

.pause-text {
    color: var(--white-primary);
    font-size: 1em;
    margin-top: 10px;
    opacity: 0.8;
}

/* ボタンのスタイルを統一 */
.game-button {
    background-color: #000;
    color: #fff;
    border: 1px solid #0ff;
    padding: 10px 20px;
    margin: 5px;
    cursor: pointer;
    font-family: 'Orbitron', sans-serif;
    transition: all 0.3s ease;
}

.game-button:hover {
    background-color: #0ff;
    color: #000;
    box-shadow: 0 0 10px #0ff;
}

/* クリア画面のスタイル */
#clear-screen {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -120%);
    background: rgba(0, 0, 0, 0.9) !important;
    border: 2px solid var(--accent-color) !important;
    animation: glow 2s infinite;
    backdrop-filter: blur(8px);
    border-radius: var(--border-radius);
    min-width: 300px;
    padding: 30px !important;
    box-sizing: border-box;
    z-index: 1000;
}

#clear-screen h2 {
    color: var(--accent-color);
    margin: 0 0 20px 0;
    font-size: 2.5em;
    text-shadow: 0 0 10px var(--accent-color),
                 0 0 20px var(--accent-color),
                 0 0 30px var(--accent-color);
    letter-spacing: 4px;
    font-weight: 700;
    text-transform: uppercase;
}

#clear-screen .settings-info {
    margin: 15px 0;
    padding: 15px;
    background-color: rgba(0, 0, 0, 0.5);
    border: 1px solid rgba(0, 255, 255, 0.2);
    border-radius: 3px;
    text-align: left;
    color: var(--white-primary);
}

#clear-screen .settings-info p {
    margin: 5px 0;
    color: var(--white-primary);
}

.clear-buttons {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 15px;
}

#clear-screen .game-button {
    background: transparent;
    color: var(--white-primary);
    border: 1px solid var(--accent-color);
    padding: 10px 20px;
    font-family: 'Orbitron', sans-serif;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
}

#clear-screen .game-button:hover {
    background: var(--accent-color);
    color: var(--black-primary);
}

/* レスポンシブ対応 */
@media (max-width: 768px) {
    :root {
        --grid-size: 32px;
    }

    body {
        padding: 10px;
    }

    h1 {
        font-size: 1.5rem;
        margin-bottom: 30px;
    }

    #game-screen {
        padding: 10px;
    }

    .game-controls {
        padding: 0 10px;
    }

    .controls-container {
        flex-direction: column;
        gap: 15px;
    }

    .custom-audio-player {
        width: 100%;
        max-width: none;
    }

    .reset-button {
        width: 100%;
    }
}

@media (max-width: 480px) {
    :root {
        --grid-size: 28px;
    }

    .settings-container {
        padding: 1rem;
    }

    .setting-group {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
}

/* ルールセクションを横並びに */
.rules-sections-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin: 15px 0;
}

.rules-section {
    margin: 0;
    height: 100%;
    box-sizing: border-box;
}

/* スペシャルルールは全幅で表示 */
.special-rule {
    grid-column: 1 / -1;
    margin: 15px 0 0 0;
    text-align: center;
    padding: 15px;
}

/* モバイル向けのルールスタイル調整 */
@media (max-width: 768px) {
    .rules-sections-container {
        grid-template-columns: 1fr;
    }

    .rules-section {
        padding: 15px;
    }

    .rules-section li {
        font-size: 0.9em;
    }

    .special-rule {
        font-size: 0.9em;
    }
}

/* ホバー効果の強調 */
.cell:not(.open):hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 10px var(--accent-glow);
    z-index: 1;
}

body[data-current-state="black"] .cell:not(.open):hover {
    box-shadow: 0 2px 10px rgba(0, 255, 255, 0.3);
}

/* フッタースタイル */
.footer {
    width: 100%;
    padding: 20px;
    background: rgba(0, 0, 0, 0.8);
    border-top: 1px solid var(--accent-color);
    margin-top: auto;
    box-sizing: border-box;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.8em;
    line-height: 1.6;
}

.footer-credits {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid rgba(0, 255, 255, 0.1);
}

.footer-credits p {
    margin: 5px 0;
}

.footer-credits a {
    color: var(--accent-color);
    text-decoration: none;
    transition: all 0.3s ease;
}

.footer-credits a:hover {
    text-shadow: 0 0 8px var(--accent-color);
    text-decoration: underline;
}

/* 選択防止のスタイルを追加 */
.settings-container,
.game-controls,
.custom-audio-player,
#clear-screen,
#game-over-screen,
.pause-overlay {
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    touch-action: manipulation;
}

.footer-tweet {
    margin-top: 20px;
    text-align: center;
}

.footer-x-button {
    background: #000000;
    border: 2px solid var(--accent-color);
    color: #ffffff;
    padding: 8px 16px;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    font-size: 14px;
    font-weight: 700;
    cursor: pointer;
    border-radius: 9999px;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    min-height: 36px;
    text-decoration: none;
    box-shadow: 0 0 10px rgba(0, 255, 255, 0.2);
}

.footer-x-button:hover {
    background: var(--accent-color);
    color: var(--black-primary);
    transform: translateY(-1px);
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.4);
}

.x-logo {
    fill: currentColor;
    width: 16px;
    height: 16px;
}