Style the first <td> column of a table differently

If you've to support IE7, a more compatible solution is:

/* only the cells with no cell before (aka the first one) */
td {
    padding-left: 20px;
}
/* only the cells with at least one cell before (aka all except the first one) */
td + td {
    padding-left: 0;
}

Also works fine with li; general sibling selector ~ may be more suitable with mixed elements like a heading h1 followed by paragraphs AND a subheading and then again other paragraphs.

You could use the n-th child selector.

to target the nth element you could then use:

td:nth-child(n) {  
  /* your stuff here */
}

(where n starts at 1)