PNG transparency Problem

Hi there,
Can you help me please. On my site www.chevalblanc.ch the .png image of the logo appears bad (very bad really) on almost all versions of Internet Explorer and Windows mobile.
Thanks

Hello there,

Yes, unfortunately, different browsers render image in different way. When width or height is used to resize images, especially IE will ensure they look incredibly ugly. There is nothing we can do regarding this, but there are few fixes which various developers suggested over time so you can try them.

Apply custom css code below:

img.site-logo {
    image-rendering: -moz-crisp-edges;         /* Firefox */
    image-rendering:   -o-crisp-edges;         /* Opera */
    image-rendering: crisp-edges;
    -ms-interpolation-mode: nearest-neighbor;  /* IE (non-standard property) */
}

And also you can try to replace -ms-interpolation with following code if there is no result:
-ms-interpolation-mode: bicubic;

You can apply provided css code with this plugin https://wordpress.org/plugins/simple-custom-css/

Let us know how this turned out.
All the Best!