Blurry featured picture

Hi, i have a problem with image resolution for the featured pictures of my pages, they all appear very blurry despite being 1000+ pixels width.

Site URL is http://www.lesjardinsdelamartine.fr/

I tried using CSS with

    .single-thumb img{
       min-width: 100%;
       min-height: 100%;
    } 

but it didn’t work.

Can you help me with this please ?

Thanks

Hello there,

The default thumbnail size is limited to 700px maximum width. To change it, you can use the Simple Image Sizes plugin. Once activated, go to Settings menu; and choose Media; then find the astrid-large-thumb size name row. Then enter 99999 for maximum width to disallow down-scaling. Save.

Afterwards, you may need to regenerate all thumbnail images with new defined size. You could use this plugin.

Regards,
Kharis