Is the placeholder text in a content editable div counted as disabled text?

Question

With IE and using Window's default Black high contrast mode, the disabled text should have a green color. However, I found in my app, the placeholder text in <input> does have a green color but the placeholder text in content-editable div will remain the color I give it in normal mode. Below is the HTML I wrote:

 <input type="text" autocomplete="off" placeholder="Name" aria-label="Enter your name" tabindex="1"></input>
 <div  contenteditable="true" data-placeholder="in case this div is empty"></div>
 The css for the div to work is div {margin:1em; border:solid;}
                                div:empty:before {content:attr(data-placeholder);
                                                  color:gray}

The div example can be found at http://codepen.io/gcyrillus/pen/hzLIE. What is really the concept of disabled text? I'm guessing placeholder in content-editable div will not be counted as 'disabled text'? If so, how to make it a 'disabled text'? Thanks so much in advance!