body {
    background-color:#121212;
    color:white;
    text-align: center;
    margin: 0;
    padding: 10px;
    box-sizing: border-box;
}

*, *::before, *::after {
    box-sizing: border-box;
}

#head1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: white;
    font-family: "Roboto Mono", monospace;
    font-optical-sizing: auto;
    font-style: normal;
    margin-top: 60px; 
}

#startBtn{
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: bold;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    margin-bottom: 20px;
    transition: 0.3s;
}

#startBtn:hover{
    transform: scale(1.05);
}

.btn {
    height: 200px;
    width: 200px;
    border-radius: 20%;
    border : 10px solid black;
    margin: 2.5rem;
}

.btn:hover{
    transform: scale(1.05);
    transition: 0.2s;
}

.btn-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.line-one, .line-two {
    display: flex;
    justify-content: center;
}

.red {
    background-color: #d95980;
    box-shadow: 0 0 15px #d95980;
}

.yellow {
    background-color: #f99b45;
    box-shadow: 0 0 15px #f99b45;
}

.green {
    background-color: #63aac0;
    box-shadow: 0 0 15px #63aac0;
}

.purple {
    background-color: #819ff9;
    box-shadow: 0 0 15px #819ff9;
}

.flash {
    box-shadow: 0 0 30px white;
    transform: scale(1.05);
}
.userflash {
    background-color: green;
}

.difficulty{
    margin: 10px;
}

.mode{
    padding: 10px 20px;
    margin: 5px;
    border-radius: 8px;
    cursor: pointer;
}

.selected{
    background-color: #63aac0;
    color: white;
}

#highScore{
    position: absolute;
    top: 20px;
    right: 30px;

    font-size: 1.2rem;
    font-weight: bold;
    color: white;

    padding: 10px 15px;
    border-radius: 10px;

    background-color: rgba(255,255,255,0.1);
    backdrop-filter: blur(5px);
}

@media (max-width: 600px) {
    #head1 {
        font-size: 1.75rem;
        margin-top: 70px; 
    }

    #highScore {
        position: absolute;
        top: 15px;
        right: 50%;
        transform: translateX(50%); 
        font-size: 1rem;
        padding: 6px 12px;
        width: max-content;
    }

    .btn {
        height: 120px;
        width: 120px;
        border-width: 6px; 
        margin: 1rem;      
    }
    
    .btn:hover, #startBtn:hover {
        transform: none;
    }
}