CSS Application Basics Tutorial: Basic knowledge

Basic knowledge of application

The application of CSS is not difficult, but please refer to the basic understanding here, some words have a little basic concepts, for you look at the back of the teaching will be helpful, it looks like it will not be too strenuous!

I. Understanding of BASIC terminology:

Symbol (Element): the tag (tag) in the HTML basic syntax.

attribute: An attribute used to describe a label attribute.

For example:

　　 , HR is the label, width is the attribute, and 80% is the value of the Width property.

Property: Used to describe the characteristics of a component. Equivalent to the attributes in the basic HTML syntax.

Style: A property of a group or array that describes the characteristics of a component.

Selector (selector): A component of the applied style.

For example:

h3{Color:blue}, H3 is the pick, color is the property, BLUE is a color value.

Second, the basic unit of understanding:

There are two units of relative units and absolute units to express the way.

Relative units:

"em": the proportional factor relative to the letter height.

"EN": proportional factor relative to the font size.

"%": an example of a percentage relative to the length unit (usually the size of the current font).

Absolute Unit:

' In ': inches.

"cm": cm.

"MM": mm.

"px": Pixel (System preset unit).

"PC": Pica, printing type unit.

"PT": Like Dot.

Relative relationship: 1in= 6pc= 72pt= 2.54cm= 25.4mm

Third, the use of color awareness:

There are five different ways to represent colors.

"#RRGGBB":

The values of the red, green, and blue primaries of 0 to 2,550 values, respectively, are represented by a value of three 00 to FF 16.

"#RGB":

The abbreviated notation, which uses only three 0 to F 16 values, respectively, to represent the red, green, and blue primary values. In fact, the browser automatically expands to six-16-digit values, such as "#ABC" will change to "#AABBCC". However, it is not obvious that such a notation is accurate.

"RGB (R,G,B)":

Color is represented by the values of red, green, and blue primaries of 0 to 2,550.

"RGB (r%,g%,b%)":

A color, such as "RGB (60%,100%,75%)", that is relative to each other in red, green, and blue.

"Color_name":

Color is directly represented by the color name, and there are 141 standard color names.