Header image not responsive

Hello guys,
I notice that the header image in the frontpage I'm using is not working for mobile devices, it seems that the height is fixed so its stretch the image. I tried this solution, but still not working:

@media (max-width: 840px) {
#gk-header-mod img {
height: auto!important;
}
}

Can you help? Thank you.

Forgot the url:

http://www.eduardosantillana.com/clientes/ilbl

Hello,

It's a background image, so you should use some simple image or pattern which may be stretched and for the image, you can use another image inside the header (like the shoe on the demo website)
regarding the css code, it's correct but try to add it to Quark/css/override.css file.

Hello, finally how did you solved it?, where did you put the code?
I have the same problem...

Hello, finally how did you solved it?, where did you put the code?
I have the same problem...

Hi @gimarsa, could you provide your website URL? (Here or use private message) and I'll try to help.