#cbt-app{
max-width:900px;
margin:auto;
padding:30px;
background:#fff;
border-radius:25px;
box-shadow:0 5px 30px rgba(0,0,0,.1);
}

#timer{
position:sticky;
top:20px;
font-size:34px;
font-weight:bold;
padding:15px;
background:#eef5ff;
border-radius:14px;
margin:20px 0;
}

.question-block{
padding:20px;
}

button{
padding:15px 35px;
border:none;
border-radius:12px;
background:#0d6efd;
color:#fff;
cursor:pointer;
}