Reset row background for each block
Reset row background for each block

Now the first row of each basic block is always light instead of
changing seemingly at random.

aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust