/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --board-color: #2e8b57;
    --board-border: #1a5c38;
    --cell-border: #246b45;
    --bg-color: #1a1a2e;
    --text-color: #e0e0e0;
    --accent-color: #4fc3f7;
    --btn-color: #2e8b57;
    --btn-hover: #3aa66a;
    --modal-bg: rgba(0, 0, 0, 0.7);
}

body {
    font-family: 'Segoe UI', 'Hiragino Sans', 'Meiryo', sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 16px;
}

.container {
    width: 100%;
    max-width: 520px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

/* Header */
header {
    display: flex;
    align-items: center;
    gap: 12px;
    width: 100%;
    justify-content: center;
    position: relative;
}

h1 {
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    color: #fff;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.header-btns {
    position: absolute;
    right: 0;
    display: flex;
    align-items: center;
    gap: 6px;
}

.lang-btn {
    background: transparent;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 4px 10px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 600;
    transition: all 0.2s;
}

.lang-btn:hover {
    background: var(--text-color);
    color: var(--bg-color);
}

.icon-btn {
    background: transparent;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 4px 8px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    line-height: 1;
    transition: all 0.2s;
}

.icon-btn:hover {
    background: var(--text-color);
    color: var(--bg-color);
}

.volume-control {
    display: flex;
    align-items: center;
    gap: 4px;
}

.volume-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 60px;
    height: 4px;
    background: rgba(255, 255, 255, 0.25);
    border-radius: 2px;
    outline: none;
    cursor: pointer;
    transition: opacity 0.2s;
}

.volume-slider:disabled {
    opacity: 0.3;
    cursor: default;
}

.volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--text-color);
    cursor: pointer;
}

.volume-slider::-moz-range-thumb {
    width: 14px;
    height: 14px;
    border: none;
    border-radius: 50%;
    background: var(--text-color);
    cursor: pointer;
}

/* Score Board */
.score-board {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 10px 16px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 10px;
    gap: 8px;
}

.score {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 1.1rem;
    font-weight: 600;
    min-width: 80px;
}

.black-score {
    justify-content: flex-start;
}

.white-score {
    justify-content: flex-end;
}

.disc-icon {
    display: inline-block;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    flex-shrink: 0;
}

.disc-icon.black {
    background: radial-gradient(circle at 35% 35%, #555, #111);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
}

.disc-icon.white {
    background: radial-gradient(circle at 35% 35%, #fff, #ccc);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.turn-indicator {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--accent-color);
    text-align: center;
    flex: 1;
}

/* Board */
.board {
    display: grid;
    grid-template-columns: repeat(8, 1fr);
    grid-template-rows: repeat(8, 1fr);
    width: min(480px, calc(100vw - 40px));
    height: min(480px, calc(100vw - 40px));
    background: var(--board-border);
    border: 3px solid var(--board-border);
    border-radius: 6px;
    gap: 1px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.cell {
    background: var(--board-color);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    position: relative;
    transition: background 0.15s;
}

.cell:hover {
    background: #35a065;
}

.cell.valid-move::after {
    content: '';
    width: 30%;
    height: 30%;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.35);
    pointer-events: none;
}

.cell.last-move {
    box-shadow: inset 0 0 0 2px rgba(255, 255, 0, 0.5);
}

/* Discs */
.disc {
    width: 80%;
    height: 80%;
    border-radius: 50%;
    position: absolute;
    transition: transform 0.4s ease;
    transform-style: preserve-3d;
}

.disc.black {
    background: radial-gradient(circle at 35% 35%, #555, #111);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.5);
}

.disc.white {
    background: radial-gradient(circle at 35% 35%, #fff, #ccc);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
}

/* Flip animation */
.disc.flipping {
    animation: flip 0.5s ease-in-out;
}

@keyframes flip {
    0% {
        transform: rotateY(0deg);
    }
    50% {
        transform: rotateY(90deg);
    }
    100% {
        transform: rotateY(0deg);
    }
}

/* Place animation */
.disc.placing {
    animation: place 0.25s ease-out;
}

@keyframes place {
    0% {
        transform: scale(0);
        opacity: 0;
    }
    60% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}

/* Message */
.message {
    min-height: 24px;
    font-size: 0.9rem;
    color: #ffd54f;
    font-weight: 500;
    text-align: center;
}

/* Controls */
.controls {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 12px;
    width: 100%;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 6px;
}

.control-group label {
    font-size: 0.85rem;
    color: #aaa;
}

select {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-color);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 6px;
    padding: 6px 10px;
    font-size: 0.85rem;
    cursor: pointer;
    outline: none;
    font-family: inherit;
}

select:focus {
    border-color: var(--accent-color);
}

option {
    background: #2a2a4a;
    color: var(--text-color);
}

.btn {
    background: var(--btn-color);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 10px 24px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    font-family: inherit;
}

.btn:hover {
    background: var(--btn-hover);
}

.btn:active {
    transform: scale(0.97);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--modal-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    animation: fadeIn 0.3s ease;
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: #2a2a4a;
    padding: 32px 40px;
    border-radius: 16px;
    text-align: center;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
    animation: scaleIn 0.3s ease;
}

.modal-content h2 {
    font-size: 1.6rem;
    margin-bottom: 12px;
    color: #fff;
}

.modal-content p {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: #ccc;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes scaleIn {
    from { transform: scale(0.8); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

/* Responsive */
@media (max-width: 400px) {
    h1 {
        font-size: 1.4rem;
    }

    .score {
        font-size: 0.95rem;
        min-width: 65px;
    }

    .turn-indicator {
        font-size: 0.85rem;
    }

    .controls {
        gap: 8px;
    }

    .btn {
        padding: 8px 18px;
        font-size: 0.85rem;
    }

    .modal-content {
        padding: 24px 28px;
        margin: 16px;
    }
}

/* Hidden utility */
.hidden {
    display: none !important;
}