* {
    margin: 0;
    padding: 0;
    font-family: "Poppins", sans-serif;
    box-sizing: border-box;
}

body {
    background: #001e4d;
}

.app {
    background: #fff;
    width: 90%;
    max-width: 800px;
    margin: 100px auto 0;
    border-radius: 10px;
    padding: 30px;
}

.app h1{
    font-size: 3rem;
    color: #001e4d;
    font-weight: 600;
    border-bottom: 1px solid #333;
    padding-bottom: 30px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.app h1 select {
    font-size: 1.5rem;
    color: #001e4d;
    font-weight: 600;
    border-bottom: 1px solid #333;
    padding: 10px;
    background-color: transparent;
}

.quiz {
    padding: 20px 0;
}

.quiz h2 {
    font-size: 2rem;
    color: #001e4d;
    font-weight: 600;
}

.btn {
    background: white;
    color: #222;
    font-size: 1.5rem;
    font-weight: 500;
    width: 100%;
    border: 1px solid #222;
    padding: 10px;
    margin: 10px 0;
    text-align: left;
    border-radius: 4px;
    cursor: pointer;
    transition: all .3s;
}
.btn:hover:not([disabled]) {
    background: #222;
    color: #fff;
}
.btn:disabled {
    cursor: no-drop;
}

#next-btn {
    background: #001e4d;
    color: white;
    font-size: 1.7rem;
    font-weight: 500;
    width: 150px;
    border: none;
    padding: 10px;
    margin: 20px auto 0;
    border-radius: 4px;
    cursor: pointer;
    display: none;
}

.correct {
    background: #9aeabc;
}
.incorrect {
    background: #ff9393;
}

@media (max-width: 768px) {
    .app h1 {
        font-size: 2.5rem;
        padding-bottom: 20px;
    }
    .quiz h2 {
        font-size: 1.5rem;
        color: #001e4d;
        font-weight: 600;
    }
    .btn {
        background: white;
        color: #222;
        font-size: 1.2rem;
    }
    #next-btn {
        font-size: 1.3rem;
        width: 120px;
    }
    .correct {
        background: #9aeabc;
    }
    .incorrect {
        background: #ff9393;
    }
}