The icons in a Juicebox gallery are characters in a custom font named 'juicebox'.
The 'juicebox' font that the gallery uses is being overridden by the following CSS code on your web page:
.arrondi.ombre table tr td div div {
font-family: Verdana, Geneva, sans-serif;
}
The gallery's location in your web page matches the selectors in the CSS above and the gallery is, therefore, inheriting this code.
Maybe the easiest way to protect against this would be to open your gallery's 'jbcore/classic/theme.css' file in a plain text editor, scroll down to line 31 and change:
... to:
font-family: 'juicebox' !important;
Otherwise, you could use further CSS selectors to target only those elements on your web page which require your custom font (although the suggestion above should work and is easier to implement).
Incidentally, I notice that your gallery currently uses Juicebox-Pro v1.4.1. (the line number above refers to this version).
You might like to upgrade to the current version (v1.5.0) as many bugs have been fixed (and new features added) since v1.4.1.
Please see the Version History for a list of changes between versions.
Full details on how to download the latest version and how to upgrade existing galleries can be found on the Upgrading Juicebox support page.
To upgrade your gallery, all you would need to do is replace your gallery's 'jbcore' folder with the 'jbcore' folder from the Juicebox-Pro v1.5.0 zip package ('juicebox_pro_1.5.0/web/jbcore/').
If you want to make the adjustment above to v1.5.0, then the line to change in the 'jbcore/classic/theme.css' file is line 18.
Also, I notice that your web page contains HTML errors.
For example, your web page has two closing </head> tags and two opening <body> tags.
You can check the code on your web page with the W3C Markup Validation Service and fix the errors reported.
Once the code on your webpage validates correctly, your web page should be rendered with greater predictability and consistency across different browsers.