style.css

body,div{
    padding: 0;
    margin: 0;
    border: 0;
}
body{
    width: 100vw;
    height: 100vh;
    overflow: hidden;
}
.row{
    display: flex;
    width: 100%;
    height: 100%;
    align-items: center;
    justify-content: center;
}
.panel{
    border: 1px solid black;
    height: 50vh;
    width: 40vw;
    display: flex;
    flex-direction: column;
}
.question{
    margin:auto 0;
    text-align: center;
    user-select: none;
    margin: auto;
    padding: 5px 30px;
    border-radius: 15px;
}
.btn-generate{
    margin:auto auto;
    padding: 10px 50px;
    border-radius: 5px;
    border: 1px solid #00838f;
    background-color: #00838f;
    color: rgba(255, 255, 255, 0.87);
    font-size: 20px;
    font-weight: 600;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    text-transform: uppercase;
}
.answer{
    width: 80%;
    margin: auto;
    font-size: 30px;
}
.wrong-answer{
    background-color: #D32F2F;
    
}
.true-answer{
    background-color: #689F38;
}
.wrong-answer,
.true-answer{
    color:#ecf0f1;
}
@media (max-width: 800px) {
    .panel{
        height: 100vh;
        width: 100vw;
    }
}