:root {
    --bg-color: #f0f0f0;
    --text-color: #333;
    --board-bg: #d2b48c;
    --board-line: #8B4513;
    --button-bg: #8B4513;
    --button-hover: #a0522d;
    --container-shadow: rgba(0,0,0,0.2);
    --stone-shadow: rgba(0,0,0,0.5);
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --board-bg: #3c2f2f;
    --board-line: #5d4037;
    --button-bg: #5d4037;
    --button-hover: #795548;
    --container-shadow: rgba(0,0,0,0.6);
    --stone-shadow: rgba(255,255,255,0.1);
}

body {
    font-family: sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

h1 {
    color: var(--text-color);
}

#game-container {
    padding: 20px;
    background-color: var(--board-bg);
    border-radius: 10px;
    box-shadow: 0 10px 20px var(--container-shadow), 0 6px 6px rgba(0,0,0,0.25);
    transition: background-color var(--transition-speed);
}

#board {
    width: 510px; /* 17 * 30px */
    height: 510px; /* 17 * 30px */
    border: 2px solid var(--board-line);
    background-color: var(--board-bg);
    position: relative;
    background-image:
        linear-gradient(to right, var(--board-line) 1px, transparent 1px),
        linear-gradient(to bottom, var(--board-line) 1px, transparent 1px);
    background-size: 30px 30px;
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

.cell {
    position: absolute;
    width: 30px;
    height: 30px;
    transform: translate(-50%, -50%);
    border-radius: 50%;
    cursor: pointer;
}

.stone {
    width: 26px;
    height: 26px;
    border-radius: 50%;
    position: absolute;
    top: 2px;
    left: 2px;
    box-shadow: 1px 1px 3px var(--stone-shadow);
}

.black {
    background-color: black;
    border: 1px solid #333;
}

.white {
    background-color: white;
    border: 1px solid #ccc;
}

#controls-container {
    position: absolute;
    top: 20px;
    right: 20px;
}

#theme-toggle {
    padding: 8px 16px;
    border-radius: 20px;
    border: 2px solid var(--button-bg);
    background-color: transparent;
    color: var(--text-color);
    cursor: pointer;
    font-weight: bold;
    transition: all var(--transition-speed);
}

#theme-toggle:hover {
    background-color: var(--button-bg);
    color: white;
}

#status-container {
    margin-top: 20px;
    text-align: center;
}

#status {
    font-size: 1.2em;
    margin-bottom: 10px;
    color: var(--text-color);
}

#new-game {
    padding: 10px 20px;
    font-size: 1em;
    border: none;
    border-radius: 5px;
    background-color: var(--button-bg);
    color: white;
    cursor: pointer;
    transition: background-color var(--transition-speed);
}

#new-game:hover {
    background-color: var(--button-hover);
}