Solution 1 :

id selector has to be prefixed with # in css:

#boxone {
font-size:40;background-color: red;padding: 20px;

#boxtwo {
padding:20px;background-color: blue;

Solution 2 :

You are using gave boxone and boxtwo an id attribute, this should be #boxone and #boxtwo in CSS, if you don’t want to change your CSS file then give them a class attribute in the HTML:

<div class="boxone"> One </div>
<div class="boxtwo"> Two</div> 

Problem :

It’s like I try something one day and it works and I go back to virtually the same thing the next day with a few different tweeks and it doesn’t work :////.

** the css is posted below but it’ supposed to be on a different page. Any help would be appreciated. Thanks!!

    <!DOCTYPE html> 
<title> #Sandbox </title>
<head><link rel="stylesheet" type="text/css" href="sandbox.css">  </head>

<div id="boxone"> One </div>
<div id="boxtwo"> Two</div>   

.boxone {font-size:40;background-color: red;padding: 20px;}

.boxtwo {padding:20px;background-color: blue;}