A page layout may be designed in a rough paper and pencil sketch before producing, or produced during the design process to the final form. Both design and production may be achieved using hand tools or page layout software. Producing a web page may require knowledge of markup languages along with WYSIWYG software. Special considerations must be made for how the layout of an HTML page will change (reflow) when resized by the end-user. Cascading style sheets are often required to keep the page layout consistent between web browsers.