My Background Color Will Not Change!

I am a pretty smart guy and I understand html, but for some reason every time I modify my style.css page and change the background it always stays with the default, which is gray background. Can someone tell me how I can insert a different color in my background. My blog is at https://www.davidjcastle.com . Below is the code I have in my script right now:

/* Begin Typography & Colors */
body {
font-size: 62.5%; /* Resets 1em to 10px */
font-family: Verdana, Arial, Sans-Serif;
background-color: #ffffff;
color: #ffffff;
text-align: center;
}

I am confused if I have ‘ffffff’ in my code shouldn’t my background be white? I need help.

Thanks.

~ David