[fix] simple theme: fix layout image detail on mobile

the width of #main_results #results.image-detail-open.only_template_images
was set to 59.25rem. On mobile, the images overflowed on right side of
the viewport, which creates a horizontal scroll.

This commit set the value to min(98%, 59.25rem) whatever the max-width is.

searx/static/themes/simple/src/less/detail.less

@@ -1,5 +1,5 @@
 #main_results #results.image-detail-open.only_template_images {
-  width: 59.25rem !important;
+  width: min(98%, 59.25rem) !important;
 }
 
 #main_results #results.only_template_images.image-detail-open #backToTop {