body{
font-family:Arial;
max-width:600px;
margin:auto;
padding:40px;
}

#slots{
display:grid;
grid-template-columns:repeat(4,1fr);
gap:10px;
margin:20px 0;
}

.slot{
padding:10px;
border:1px solid black;
cursor:pointer;
text-align:center;
}

.slot.selected{
background:black;
color:white;
}

button{
padding:10px 20px;
cursor:pointer;
}

input{
display:block;
margin:10px 0;
padding:10px;
width:100%;
}