To make XenForo media gallery's markup more compatible with W3C standards, please consider adding alt="" tag to media gallery thumbnails at forum home. This tag presents at /media/ thumbnail images.
Example URL: http://validator.w3.org/check?uri=https://xenforo.com/community/&charset=(detect+automatically)&doctype=Inline&group=0
Additional info about alt="" http://www.w3.org/QA/Tips/altAttribute
Example URL: http://validator.w3.org/check?uri=https://xenforo.com/community/&charset=(detect+automatically)&doctype=Inline&group=0
Line 3416, Column 121: An img element must have an alt attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
…-da067213d71c593d24aaef253c3d275d.jpg?1415929303" class="thumbImage lazyOwl" />
Additional info about alt="" http://www.w3.org/QA/Tips/altAttribute