* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
    user-select: none;
}
body {
    background: linear-gradient(135deg, #0A0519, #1a1237);
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
main {
    display: flex;
    flex-direction: column;
    align-items: center;
}
#header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
    width: 200px;
}
.player {
    background: #17122A;
    width: 60px;
    height: 60px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 30px;
    font-weight: bold;
    cursor: pointer;
    border-radius: 12px;
    border: solid 4px #17122A;
    opacity: 0.5;
    transition: all 0.3s ease;
}
.player-active {
    opacity: 1;
    border-color: #2A2343;
}
#xPlayerDisplay { color: #1892EA; }
#oPlayerDisplay { color: #A737FF; }
#titleHeader {
    font-size: 20px;
    align-self: center;
}
#board {
    display: grid;
    grid-template-columns: repeat(3, 70px);
    grid-template-rows: repeat(3, 70px);
    gap: 12px;
}
.cell {
    background: #17122A;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 36px;
    font-weight: bold;
    cursor: pointer;
    transition: background 0.3s;
}
.cell:hover {
    background: #2A2343;
}
#restartBtn {
    margin-top: 20px;
    width: 235px;
    background: #17122A;
    padding: 10px;
    border: none;
    border-radius: 12px;
    font-weight: bold;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s;
    color: white;
}
#restartBtn:hover {
    background: #2A2343;
}

/* Menu */
#menu {
    text-align: center;
}
#menu h1 {
    margin-bottom: 20px;
}
#menu button {
    background: #17122A;
    border: none;
    color: white;
    padding: 10px 20px;
    margin: 5px;
    border-radius: 12px;
    cursor: pointer;
    transition: background 0.3s;
}
#menu button:hover {
    background: #2A2343;
}
#menu button.selected {
    border: 2px solid #2A2343;
}