Your syntax was incorrect.
td { text-align: right }; /* This was being applied */
td:first-child { text-align: left }; /* This wasn't.. */
Should be:
td { text-align: right; }
td:first-child { text-align: left; }
Note the semi-colons - they shouldn't be outside of the brackets {}
Other than that, you were using :first-child
properly.
jsFiddle demo
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