Tile CSS in Child Theme

I have pasted the following CSS from the widget css into my child theme. It should override the widget CSS but I am seeing no changes. Firebug also shows the original CSS. Am I missing something?

I know it’s not caching because I have made non-widget CSS changes and they show up.

‘.wp-tile-container .grid .title {
font-size: 16px;
font-weight: 600;
line-height: 1.2em;
height: 3.2em;
padding: 2px 5px 5px;
}’

http://ww.wp.xz.cn/plugins/wp-tiles/