:root {
    --bg-color: #f5f5f5;
    --text-color: #333;
    --board-color: #2d8659;
    --cell-border: #1a5236;
    --valid-move: rgba(255, 215, 0, 0.5);
    --black-piece: #000000;
    --white-piece: #ffffff;
    --shadow: rgba(0, 0, 0, 0.1);
    --card-bg: #ffffff;
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --board-color: #1e5a3d;
    --cell-border: #0f2e1f;
    --shadow: rgba(0, 0, 0, 0.3);
    --card-bg: #2a2a2a;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 800px;
    width: 100%;
}

header {
    text-align: center;
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    font-size: 3em;
    color: var(--text-color);
    text-shadow: 2px 2px 4px var(--shadow);
}

.controls {
    display: flex;
    gap: 10px;
}

.btn {
    padding: 10px 20px;
    font-size: 16px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: var(--card-bg);
    color: var(--text-color);
    box-shadow: 0 2px 5px var(--shadow);
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px var(--shadow);
}

.btn:active {
    transform: translateY(0);
}

.btn-primary {
    background-color: #4a90e2;
    color: white;
}

.btn-primary:hover {
    background-color: #357abd;
}

.btn-danger {
    background-color: #e74c3c;
    color: white;
}

.btn-danger:hover {
    background-color: #c0392b;
}

.game-info {
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px var(--shadow);
}

.score-section {
    display: flex;
    justify-content: space-around;
    margin-bottom: 15px;
}

.player-score {
    text-align: center;
}

.score-label {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 5px;
    font-weight: bold;
}

.piece {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 2px solid var(--cell-border);
    display: inline-block;
}

.black-piece {
    background-color: var(--black-piece);
}

.white-piece {
    background-color: var(--white-piece);
}

.score {
    font-size: 2em;
    font-weight: bold;
}

.current-player {
    text-align: center;
    font-size: 1.2em;
    font-weight: bold;
    color: var(--text-color);
}

.board {
    display: grid;
    grid-template-columns: repeat(8, 1fr);
    gap: 2px;
    background-color: var(--cell-border);
    padding: 2px;
    border-radius: 10px;
    max-width: 600px;
    margin: 0 auto;
    box-shadow: 0 4px 15px var(--shadow);
}

.cell {
    aspect-ratio: 1;
    background-color: var(--board-color);
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    position: relative;
    transition: background-color 0.2s;
}

.cell:hover {
    background-color: color-mix(in srgb, var(--board-color) 85%, white);
}

.cell.valid-move {
    background-color: var(--valid-move);
}

.cell.valid-move:hover {
    background-color: rgba(255, 215, 0, 0.7);
}

.cell.last-move {
    background-color: rgba(100, 149, 237, 0.6);
    animation: highlightMove 1.5s ease-in-out;
}

@keyframes highlightMove {
    0%, 50% {
        background-color: rgba(100, 149, 237, 0.9);
    }
    100% {
        background-color: rgba(100, 149, 237, 0.6);
    }
}

.disc {
    width: 80%;
    height: 80%;
    border-radius: 50%;
    border: 2px solid rgba(0, 0, 0, 0.2);
    animation: placeDisc 0.3s ease-out;
}

@keyframes placeDisc {
    from {
        transform: scale(0);
    }
    to {
        transform: scale(1);
    }
}

.disc.black {
    background-color: var(--black-piece);
    box-shadow: inset -2px -2px 4px rgba(255, 255, 255, 0.2),
                inset 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.disc.white {
    background-color: var(--white-piece);
    box-shadow: inset -2px -2px 4px rgba(0, 0, 0, 0.2),
                inset 2px 2px 4px rgba(255, 255, 255, 0.5);
}

.game-controls {
    margin-top: 20px;
    text-align: center;
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 10px var(--shadow);
}

.mode-selection {
    margin-top: 15px;
    display: flex;
    justify-content: center;
    gap: 20px;
}

.mode-selection label {
    display: flex;
    align-items: center;
    gap: 5px;
    cursor: pointer;
}

.mode-selection input[type="radio"] {
    cursor: pointer;
}

.color-selection {
    margin-top: 15px;
    display: flex;
    justify-content: center;
    gap: 15px;
    align-items: center;
}

.color-selection.hidden {
    display: none;
}

.color-selection label {
    display: flex;
    align-items: center;
    gap: 5px;
    cursor: pointer;
}

.color-selection input[type="radio"] {
    cursor: pointer;
}

.player-names {
    margin-top: 15px;
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

.player-names.hidden {
    display: none;
}

.name-input-group {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.name-input-group label {
    font-weight: bold;
    font-size: 0.9em;
}

.name-input-group input[type="text"] {
    padding: 8px 12px;
    border: 2px solid var(--cell-border);
    border-radius: 5px;
    font-size: 1em;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: border-color 0.2s;
}

.name-input-group input[type="text"]:focus {
    outline: none;
    border-color: #4a90e2;
}

.game-over {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.game-over.hidden {
    display: none;
}

.game-over-content {
    background-color: var(--card-bg);
    padding: 40px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 5px 20px var(--shadow);
    max-width: 400px;
}

.game-over-content h2 {
    margin-bottom: 20px;
    font-size: 2.5em;
}

.game-over-content p {
    margin-bottom: 30px;
    font-size: 1.2em;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal.hidden {
    display: none;
}

.modal-content {
    background-color: var(--card-bg);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 5px 20px var(--shadow);
    min-width: 300px;
}

.leaderboard-content {
    max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
}

.modal-content h2 {
    margin-bottom: 20px;
    text-align: center;
}

.color-picker-group {
    margin-bottom: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.color-picker-group label {
    font-weight: bold;
}

.color-picker-group input[type="color"] {
    width: 60px;
    height: 40px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.modal-actions {
    margin-top: 25px;
    display: flex;
    gap: 10px;
    justify-content: center;
}

.leaderboard-list {
    margin-bottom: 20px;
    max-height: 400px;
    overflow-y: auto;
}

.leaderboard-item {
    background-color: var(--bg-color);
    padding: 15px;
    margin-bottom: 10px;
    border-radius: 8px;
    border-left: 4px solid #4a90e2;
}

.leaderboard-item.winner-black {
    border-left-color: var(--black-piece);
}

.leaderboard-item.winner-white {
    border-left-color: var(--white-piece);
}

.leaderboard-item.tie {
    border-left-color: #95a5a6;
}

.leaderboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
    font-weight: bold;
}

.leaderboard-players {
    font-size: 1.1em;
}

.leaderboard-score {
    display: flex;
    gap: 15px;
    font-size: 0.95em;
    color: var(--text-color);
    opacity: 0.8;
}

.leaderboard-date {
    font-size: 0.85em;
    color: var(--text-color);
    opacity: 0.6;
    margin-top: 5px;
}

.leaderboard-empty {
    text-align: center;
    padding: 40px 20px;
    color: var(--text-color);
    opacity: 0.6;
    font-style: italic;
}

@media (max-width: 768px) {
    h1 {
        font-size: 2em;
    }
    
    header {
        flex-direction: column;
        gap: 15px;
    }
    
    .board {
        max-width: 100%;
    }
    
    .mode-selection {
        flex-direction: column;
        gap: 10px;
    }
}