When exporting to HTML file, the table width is wrongly evaluated when the table width (in the original document) is set to fixed width.

Workaround: 
IEnumerable<Table> tables = this.document.EnumerateChildrenOfType<Table>();
foreach (Table table in tables)
{
table.PreferredWidth = new TableWidthUnit(TableWidthUnitType.Auto);
}

IEnumerable<Paragraph> paragraphs = this.document.EnumerateChildrenOfType<Paragraph>();
foreach (Paragraph paragraph in paragraphs)
{
paragraph.Spacing.SpacingAfter = 0;
}