W3C CSS2 Cascading Style Sheets, level 2 - instructional media + ...

Value: | inherit
Initial: 2
Applies to: block-level elements
Inherited: yes
Percentages: N/A
Media: visual, paged
’widows’
Value: | inherit
Initial: 2
Applies to: block-level elements
Inherited: yes
Percentages: N/A
Media: visual, paged
The ’orphans’ property specifies the minimum number of lines of a paragraph
that must be left at the bottom of a page. The ’widows’ property specifies the
minimum number of lines of a paragraph that must be left at the top of a page.
Examples of how they are used to control page breaks are given below.
For information about paragraph formatting, please consult the section on line
boxes [p. 105] .
13.3.4 Allowed page breaks
In the normal flow, page breaks can occur at the following places:
1. In the vertical margin between block boxes. When a page break occurs here,
the computed values [p. 70] of the relevant ’margin-top’ and ’margin-bottom’
properties are set to ’0’.
2. Between line boxes [p. 105] inside a block [p. 97] box.
These breaks are subject to the following rules:
Rule A: Breaking at (1) is allowed only if the ’page-break-after’ and
’page-break-before’ properties of all the elements generating boxes that
meet at this margin allow it, which is when at least one of them has the value
’always’, ’left’, or ’right’, or when all of them are ’auto’.
Rule B: However, if all of them are ’auto’ and the nearest common ancestor
of all the elements has a ’page-break-inside’ value of ’avoid’, then breaking
here is not allowed.
Rule C: Breaking at (2) is allowed only if the number of line boxes [p. 105]
between the break and the start of the enclosing block box is the value of
’orphans’ or more, and the number of line boxes between the break and the
end of the box is the value of ’widows’ or more.
Rule D: In addition, breaking at (2) is allowed only if the ’page-break-inside’
property is ’auto’.
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