Some basic knowledge of HTML/CSS that you need to pay attention to_html/css_WEB-ITnose

border:0; The border exists but is unrealistic and takes up memory

border:none; the border is not rendered

HTML writing specifications ：

1. Label line wrap. 2. Label indentation. 3. The label should be closed. 4. The tag name attribute cannot be empty. 5. First things first! doctype declaration. 6. The encoding format is UTF-8. 7. Labels must be in half-width English lowercase letters. 8. Reasonable comments. 9. Class names and id names must have semantic comments. 10. Reasonable nesting.

Relative positioning: Relative positioning requires a reference object, but this reference is itself, which means that the relative positioning position is not set, but only if it is set can TOP, LEFT These take effect, that is, only when they are set can they be offset relative to their original positions. The original positions are retained, and other layers will be masked after the offset.

Absolute positioning: It is impossible to have absolute positioning in the layout. No matter what, there is a reference position. The reference position of absolute positioning depends on whether its superior or superior has positioned it, that is, whether it has position:relative; When the layer to be absolutely positioned is set to refer to the position, you can use TOP and LEFT to determine the position. If its superior or superior is not positioned, it will only be based on the position of the BODY. Positioning, and one final point, absolute positioning will cause the element to break out of the document flow.

Usage of padding and margin: padding: parent element and child element; margin: child element of the same level. Padding will affect the border.

The difference between block elements and line elements: 1. Block elements occupy a line by themselves, and line elements do not occupy a line by themselves. 2. The width and height can be set for block elements, but not for line elements. 3. Block elements can set margin and padding values, while row elements can only set horizontal padding and margin values.

Common browser hacks:

“-″ minus sign is a hack exclusive to IE6

“9″ IE6/IE7/IE8/IE9/IE10 All take effect

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