You can set a table to use the full width of a page without changing it's width in browsers:
@media print{
.someClass { width: 100% }
}
<table class="someClass">...</table>
This also works with other elements, e.g. images.
The "100%" refer to the width of the parent element So if the element you set to "width: 100%" is nested in an other element this surrounding element also has to be set to "width: 100%".