:root {
    --bg-color: #2c3e50;
    --primary-color: #2980b9;
    --secondary-color: #34495e;
    --accent-color: #ecf0f1;
    --text-color: #ffffff;
    --x-color: #e74c3c;
    --o-color: #2ecc71;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    text-align: center;
    font-family: 'Poppins', sans-serif;
}

/* Startup Modal */
#startup-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: 100;
    transition: visibility 0.2s, opacity 0.2s linear;
}

.modal-content {
    background-color: var(--secondary-color);
    padding: 2rem 3rem;
    border-radius: 1rem;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.modal-content h2 {
    color: var(--accent-color);
}

.modal-content input {
    font-size: 1rem;
    padding: 0.75rem;
    border-radius: 0.5rem;
    border: 2px solid var(--primary-color);
    background: var(--bg-color);
    color: var(--text-color);
}

#start-game-btn {
    background-color: var(--o-color);
}

/* Main Content and Header */
header {
    margin: 2rem 0;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
}

.scoreboard {
    display: flex;
    justify-content: center;
    gap: 4rem;
    margin-top: 1rem;
    font-size: 1.2rem;
}

.score span {
    font-size: 2.5rem;
    font-weight: 600;
}

/* Game Area */
main {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

#turn-indicator {
    font-size: 1.5rem;
    font-weight: 600;
    height: 2rem; /* Reserve space to prevent layout shift */
}

.container {
    height: 65vmin;
    display: flex;
    justify-content: center;
    align-items: center;
}

.game {
    height: 60vmin;
    width: 60vmin;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    gap: 1.5vmin;
}

.box {
    height: 18vmin;
    width: 18vmin;
    border-radius: 1rem;
    border: none;
    box-shadow: 0 0 1rem rgba(0, 0, 0, 0.3);
    font-size: 10vmin;
    font-weight: 700;
    background-color: var(--secondary-color);
    cursor: pointer;
    transition: background-color 0.2s ease-in-out;
}

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

.x-text { 
    color: var(--x-color); 
}

.o-text { 
    color: var(--o-color); 
}

/* Buttons */
#reset-btn, #new-btn, #start-game-btn {
    padding: 1rem 2rem;
    font-size: 1.25rem;
    border-radius: 1rem;
    border: none;
    background-color: var(--primary-color);
    color: var(--text-color);
    cursor: pointer;
    transition: transform 0.2s ease;
}

#reset-btn:hover, #new-btn:hover, #start-game-btn:hover {
    transform: scale(1.05);
}

/* Winner Message */
#msg {
    color: var(--accent-color);
    font-size: 8vmin;
}

.msg-container {
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    width: 100vw;
    background-color: rgba(0, 0, 0, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    gap: 4rem;
}

.hide {
    /* Correct way to hide elements completely */
    display: none !important;
}

/* Responsive Design */
@media (max-width: 768px) {
    .scoreboard {
        gap: 2rem;
        font-size: 1rem;
    }

    .score span {
        font-size: 2rem;
    }

    h1 {
        font-size: 2.5rem;
    }

    .modal-content {
        margin: 1rem;
        padding: 1.5rem 2rem;
    }

    #msg {
        font-size: 6vmin;
    }
}

@media (max-width: 480px) {
    .scoreboard {
        flex-direction: column;
        gap: 1rem;
    }

    h1 {
        font-size: 2rem;
    }

    .game {
        height: 70vmin;
        width: 70vmin;
    }

    .box {
        height: 20vmin;
        width: 20vmin;
        font-size: 12vmin;
    }
}