:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --accent-hover: #0ea5e9;
    --stone-color: #cbd5e1;
    --danger-color: #ef4444;
    --success-color: #22c55e;
    color-scheme: dark;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 600px;
    padding: 2rem;
    text-align: center;
}

header h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, var(--accent-color), #818cf8);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

header p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.game-board {
    background-color: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.stones-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    min-height: 100px;
}

.stone {
    width: 20px;
    height: 20px;
    background-color: var(--stone-color);
    border-radius: 50%;
    box-shadow: 0 0 10px rgba(203, 213, 225, 0.3);
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.stone.removing {
    transform: scale(0);
    opacity: 0;
}

.stone-count {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.controls {
    margin-bottom: 2rem;
}

#status-message {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    min-height: 1.5em;
}

.button-group {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

.btn {
    background-color: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--accent-color);
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn:hover {
    background-color: var(--accent-color);
    color: var(--bg-color);
    transform: translateY(-2px);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    border-color: var(--text-secondary);
}

.btn-primary {
    background-color: var(--accent-color);
    color: var(--bg-color);
    border: none;
}

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

.hidden {
    display: none;
}

input[type="number"] {
    background-color: var(--bg-color);
    border: 1px solid var(--text-secondary);
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: 0.25rem;
    font-size: 1rem;
    width: 80px;
    text-align: center;
    margin-right: 1rem;
}

footer {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 2rem;
}

footer a {
    color: var(--accent-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}