Here are some suggestions to improve the website layout (with pictures) and to deal with the design of the site on mobile platforms.
1: When an artist has a picture on his page and a long biography written, some place is wasted below the picture. The text should fit the whole width of the page.
2: There should be links to the museums in the 'top owners of works by this artist".
3: There are two sets of tabs on the page and it may be a bit confusing. There is a "biography" tab whilst the biography is written above, etc. Perhaps we could gather all the tabs at the place, or hide the biography and add an "expand button" to reduce the length of page.
4 & 5: There should be a bibliography tab and a "history" tab.