The CSS3 software program (Cascading Style Sheets) is used to add features to the HTML5 coding software program. Such as formatting text, color, and spacing the content.
The CSS rule set, has a selector, property, value, and declaration box or rule. For example, header is the selector, height is the property, and 80px is the value. In the CSS file, the rule looks like this: header {height: 80px} (Murach, p.55).
The CSS3 software program assists in placing the content of the website according to "block", "inline", or "inline-block". An example of an inline element is an "image" that does not take an entire "row" of space on the screen in contrast to a block element that does - such as a paragraph or header
.Please refer to the link, definition of inline and block by the website w3schools.com
.An element may be floated left or right - taking the element out of the normal flow (Murach, p202). An element may be coded as absolute and/ or relative position. Absolute positioning does not move in relation to other elements on the website; in contrast, to relative that does move in relation to other elements on the website (Murach, p226).