If a container of auto width is floated right or left and has floated children either right or left, in most instances the container will expand to 100% of the available width (in these test case, this is the body element). If the floated children are inline elements, the same bug happens since floating changes the element to render as a block.
Two test cases with floated childen (either left or right) alternating in the soucre
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Two test cases with floated childen (either left or right) alternating in the soucre