Concise, as with almost all other front-end frameworks, has adopted the use of HTML5 for presentation and markup. When coupled with HTML5shiv and other polyfills, HTML5 elements will look presentable in old browsers.
However, if you would like to switch back to HTML4 or XHTML, Concise offers a simple way to accomplish just that.
First, we will want to remove the <!doctype html> from the top of our <head> section, and replace it with one of the alternatives:
HTML 4.01 Strict:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">HTML 4.01 Transitional:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">XHTML 1.0 Strict:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">XHTML 1.0 Transitional:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">XHTML 1.1:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">Other than that, all of the presentation elements present in Concise have been applied to Concise, meaning that <header> is not necessary when creating a header. Instead, you can simply have <div class="header"> in proper pre-HTML5 fashion.