Column merging investigation

Empty columns is a column that has no originating cells

Table standard discusses this under "track merging".

Compatibility

  • Edge17 has a bug where width of a colspanned cell always includes cell width + width of border spacing. It should be max(cell width, border spacing)
  • Safari matches Chrome Legacy. TD-originated columns are always merged.
  • Firefox follows the standard, but has a few bugs.

    • TD merging

    Auto table, and TD.colspan=10
  FF/Chrome Legacy/Safari: Standard. Tracks merge.
  Edge17: Tracks do not merge. Wide cell is 180px (9 * border spacing)
    auto 
    Auto table(400px), and TD.colspan=10
  FF/Chrome Legacy/Safari/Edge17: Standard. Tracks merge. Colspan cell grows because it is unconstrained.
    auto 400px 
    Auto table(130px), and TD.colspan=10
  FF/Chrome Legacy/Safari: Standard. Tracks merge. Colspan cell shrinks to min width becuase it is unconstrained.
  Edge17: Non-compliant, buggy. Wide cell too wide, narrow cell disappears.
    auto 130px 
    Fixed(400px) table, and TD.colspan=10
  Chrome/Safari: Non-compliant. Tracks merge. Cells are the same size, fixed algo distributes extra width evenly.
  Firefox: Standard.
  Edge17: Standard, buggy. Wide cell too wide. Edge's bug is that it computes max width as (width + border_spacing) instead of max(width, border_spacing).
    fixed 400px 
    Fixed(130px) table, and TD.colspan=10
  Chrome/Safari: Non-compliant.Tracks merge, cells same size.
  Firefox: Standard + buggy. Table does not grow.
  Edge17: Standard + buggy. Wide cell too wide.
    fixed 130px

    COL merging. Same tests with COL span=10 replacing TD

    Auto table
  FF/Chrome Legacy/Safari, Edge17: Standard. wide cell is 50px, tracks do merge.
    auto 
    Auto table(400px)
  FF/Chrome Legacy/Safari, Edge17: Standard. Both cells grow the same because unconstrained.
    auto 400px 
    Auto table(130px)
  FF/Chrome Legacy/Safari, Edge17: Standard. Both cells shrink.
    auto 130px 
    Fixed(400px) table
  Chrome/Safari,Firefox: Standard.
  Edge17: Buggy. Fixed cells grow to fill table.
    fixed 400px 
    Fixed(130px) table
  Chrome/Safari: Standard, very buggy. Non-collapsed columns shrink to single border spacing.
  Firefox: Standard.
  Edge17: Non-compliant, collapses columns.
    fixed 130px

    COL merging when COL has specified width.

    Auto table, COL width 30px.
  Chrome Legacy/Edge17/Safari: non-compliant, merge.
  Firefox: Standard, buggy. does not include border-spacing around columns.
    auto col 30px 
    Auto table, COL width 5%.
  Chrome Legacy/Edge17/Safari: non-compliant, merge.
  Firefox: Standard, buggy. does not include border-spacing around columns.
    auto col 10% 
    Auto table, COL width 0px.
  Everyone: merges COL
    auto col 0px