Use a proper linked CSS.
Code:
.centre {
text-align: center;
}
.padleft {
padding-left: 50px;
}
.tab1 {
padding-left: 4em;
}
.tab2 {
padding-left: 8em;
}
.tab3 {
padding-left: 12em;
}
.red {
color: red;
}
I've fixed your errors. With ADE, if you have an error in the style sheet, the entire style sheet will be ignored.