:root {
    --bg-gradient-start: #111827;
    --bg-gradient-end: #1f2937;
    --container-bg: #1f2937;
    --border-color: #374151;
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --accent-x: #34d399; /* Verde esmeralda */
    --accent-o: #f87171; /* Rojo claro */
    --button-bg: #4f46e5; /* Indigo */
    --button-hover-bg: #4338ca;
}

body {
    font-family: 'Inter', sans-serif;
    background-image: linear-gradient(145deg, var(--bg-gradient-start), var(--bg-gradient-end));
    color: var(--text-primary);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    text-align: center;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 600px;
    margin: 20px;
    padding: 40px;
    background-color: var(--container-bg);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

header h1 {
    font-size: 2.8rem;
    font-weight: 900;
    color: var(--text-primary);
    margin-bottom: 0.5em;
}

header p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 2.5em;
    line-height: 1.6;
}

#game-board {
    display: grid;
    justify-content: center;
    grid-template-columns: repeat(3, 100px);
    grid-gap: 10px;
    margin-bottom: 20px;
}

.cell {
    width: 100px;
    height: 100px;
    background-color: #374151;
    border-radius: 8px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 5rem;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.2s ease;
}

.cell:hover {
    background-color: #4b5563;
    transform: scale(1.05);
}

.cell.x::before {
    content: 'X';
    color: var(--accent-x);
}

.cell.circle::before {
    content: 'O';
    color: var(--accent-o);
}

#winning-message {
    padding: 20px;
    font-size: 1.5rem;
    color: var(--text-primary);
}

#restart-button,
.subscribe-form button {
    background-color: var(--button-bg);
    color: white;
    border: none;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: bold;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
}

#restart-button:hover,
.subscribe-form button:hover {
    background-color: var(--button-hover-bg);
    transform: translateY(-2px);
}

.hidden {
    display: none;
}

footer p {
    margin-top: 2.5em;
    font-size: 1rem;
    color: var(--text-secondary);
}

.subscribe-form {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 1em;
}

.subscribe-form input {
    padding: 12px;
    font-size: 1rem;
    border: 1px solid var(--border-color);
    background-color: #374151;
    color: var(--text-primary);
    border-radius: 8px;
    width: 250px;
}

.subscribe-form input::placeholder {
    color: var(--text-secondary);
}

@media (max-width: 600px) {
    .container {
        padding: 25px;
    }
    header h1 {
        font-size: 2.2rem;
    }
    #game-board {
        grid-template-columns: repeat(3, 80px);
    }
    .cell {
        width: 80px;
        height: 80px;
        font-size: 4rem;
    }
    .subscribe-form {
        flex-direction: column;
    }
    .subscribe-form input {
        width: 100%;
        box-sizing: border-box; /* Asegura que el padding no afecte el ancho total */
    }
}