Comment by dchest

   <img src="catcute.jpg" width="500px" height="400px" ></img>

Width and height must be specified without units (although looks like browsers accept it, probably by ignoring the unit). IMG tags are self-closing, so you can omit </img>

   <img src="wool.jpg" width="500px" height="400px" ></img>

The dog picture has wrong aspect ratio. The dog is squeezed! It should be 620 × 349 or, if 500 width or 400 height is needed, there's a good mathematical task to calculate the size of the other side.

   <br/>

No need for / in HTML.

   unicorn.html
   unicorncopy.html

Page for cats is named unicorn.html! and for computers it's unicorncopy!!!

PS I don't like that CloudFlare Pages strips .html. Too magical.