id.css

/* id styling has widespread effects */
#site a { padding-left: 10px; }

/* does nothing */
li a { padding-left: 10px; }

/* also does nothing */
.sidebar li:first a { padding-left: 10px; }

/* Another overly specific selector */
#footer a { color: red; }

.mybutton { color: white; background-color: blue; }

/* crap, now I have to add my-button to the footer. */
#footer a.mybutton { color: white; }