Images getting Lost on Chrome/IE 10 But not Firefox

I am baffled by one of our sites that, for some reason, is showing a header logo just fine on Firefox, but on Safari, IE10 and Chrome, the logo is shown as if it can’t be found.

The site is

I have checked to see that the file is there. The theme is Appply, and have verified the code to be rendered ok:

<div id="wrapper">
<header id="header">
<div class="col-full">
<a id="logo" title="OSHA Training - OSHA Guides and Standards - Litigation Support - OSHA Portal" href="http://www.osha.net/">
<img alt="OSHA Safety and Risk Management | OSHA.net" src="https://www.osha.net/wp-content/uploads/logo-graphic3.png">
</a>
<div class="header-right">
<div align="right" style="margin:0 15px 5px 0;">
<nav id="navigation" class="col-full" role="navigation">
</div>
</div>
</header>
<div id="featured-slider">
<div id="content" class="page col-full">
<div id="footer-wrapper">
</div>

Has anyone had this problem? Is there something that can be done? I’ve been working with WP for years and don’t seem to have ever had this issue before. Would appreciate any help!