Colgroup col widths
  - colgroup's purpose is to "group" cols
 
  - one can think of colgroup as always generating max(colgroup.span,1) cols, unless it has <col> children.
 
  - colgroup css_width specifies width of generated cols.
 
  - col.css_width can override colgroup width
 
colgroups with spans
cols with spans
colgroups with cols
colgroups with cols with spans
Legacy fails col with span inside colgroup test.
  
    
    
  
  
    
  
  | cg1 | 
  col1 | 
  col1 | 
  cg2 | 
  cg2 | 
  50px  | 
0% cols are ignored