site categories css- rows and columns for sub categories

I see how I can change the site categories landing page to the number of rows and columns that I want, great.

Now I want to change the sub category results to the same number of columns across the page.

I tried this in my theme’s css

UL.site-categories.site-categories-list{

margin: 0;

padding: 0;

width: 600px;

min-height: 300px;

}

#site-categories-wrapper .site-categories-list li{

display: block;

float: left;

width: 180px;

font-size:16px;

}

but I came up with bupkus.

What am I doing wrong?