style.css

*{
    box-sizing: border-box;
}

body{
    background-image: url('https://images.pexels.com/photos/1089440/pexels-photo-1089440.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940');
    background-repeat: no-repeat;
    background-size: cover;
    font-family: Arial, Helvetica, sans-serif;  
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0;
    min-height: 100vh;
    
} 

.titulo{
    background-color: white;
    text-align: center;
    position: absolute;
    border-style: solid;
    border-color: #16a085;
    border-width: 5px;
    border-radius: 5px;
    top: 30px;
    box-shadow: 0 0 15px 10px rgba(0, 0, 0, 0.2);
    max-width: 100%;
    padding: 10px;
}

.caixaPrincipal{
    background-color: white;
    border-radius: 5px;
    box-shadow: 0 0 15px 10px rgba(0, 0, 0, 0.2);
    width: 500px;
    max-width: 100%;
    overflow: hidden;
    margin-top: 100px;
}

.headerQ{
    padding: 25px;
}

h2{
    margin: 0;
    text-align: center;
    padding: 2rem;
}

ul{
    list-style-type: none;
    padding: 0;
}

ul, li{
    margin-top: 1rem;
    font-size: 1.1rem;
}

ul, li label{
    cursor: pointer;
}

button{
    background-color: black;
    border: none;
    color: white;
    display: block;
    font-family: inherit;
    cursor:pointer;
    border-style: solid;
    border-color: #16a085;
    border-width: 5px;
    padding: 1rem;
    width: 100%;
    font-size: 1.5rem;
}

button:hover{
    background-color: #16a085;
    border-style: solid;
    border-color: white;
    border-width: 5px;
    border-radius: 10px;
    transition: 0.5s;
}