You don't want me to have fun changing a site's CSS to make everything the same color (aidenpons). You end up with all this.

Because aidenpons begged so much to know how I did all this so quickly, here is the template to follow.

* {
  background: #fff !important;
  color: #000 !important;
}

Notes:

• * is known as the universal selector. It selects all elements in a page. Use of the universal selector is discouraged because it can be rather slow.
  
• That is not the proper way to use the background attribute. However, for simplicity, I did it wrong on purpose. Use background instead of background-color to kill any images used as backgrounds (they will cover up any color applied).
  
• color changes the text color. So no, going "Ctrl+F 'color' or something" is not how I did it.
  
• !important means any other instances of that attribute should be overridden. Heavy use of this is also discouraged (reasons beyond the scope here), but is required to achieve the effects seen above.