```html
.seatmap {
width: 600px;
margin: 0 auto;
}
.seat {
width: 40px;
height: 40px;
backgroundcolor: ccc;
margin: 5px;
display: inlineblock;
borderradius: 5px;
textalign: center;
lineheight: 40px;
fontweight: bold;
color: fff;
cursor: pointer;
}
.seat.available {
backgroundcolor: 90EE90;
cursor: pointer;
}
.seat.selected {
backgroundcolor: FF4500;
}
.seat.occupied {
backgroundcolor: A9A9A9;
cursor: notallowed;
}