In biology, cell theory is a scientific theory which describes the properties of cells. These cells are the basic unit of structure in all organisms and also the basic unit of reproduction.
The doctype declaration should be the very first thing in an HTML document, before the <html> tag. The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of the markup language the page is written in. The doctype declaration refers to a Document Type Definition (DTD).
The main objective of Hologram is to write your style documentation directly into the CSS files. Your CSS files are the only source required to maintain your style guide. This forces you to structure them in a way that best reflects the goals of SDD and the goals you want for your project.