CSS ~ nth child

table.list tr td:first-child{
width:50%;

}
table.list tr td:nth-child(2){
width:20%;

}
table.list tr td:nth-child(3){
width:10%;

}
table.list tr td:nth-child(4){
width:20%;
}

http://www.w3.org/TR/css3-selectors/