border, select, fixed in html

This article mainly introduces the border, select, and fixed in dynamically generated HTML. It has certain reference value. Now I share it with you. Friends in need can refer to

Border in HTML

Only the border-radius of a certain corner

border-top-left-radius: 8px; upper left corner arc 8px;
border-top- right-radius: 8px; upper right corner
border-bottom-left-radius: 8px; lower left corner
border-bottom-right-radius: 8px; lower right corner

html select statement

1. Usage method

<select name="site">
    <option value="0">zero</option>
    <option value="1">one</option>
    <option value="2">two</option>
    <option value="3">three</option>
    <option value="4">four</option>
    <option value="5">five</option>
</select>

2. Add default selection

一般默认选中第一个选项，也可以手动添加选中状态，即在对应的option中添加selected="selected"

<select name="site">
    <option value="0">zero</option>
    <option value="1">one</option>
    <option value="2">two</option>
    <option value="3">three</option>
    <option value="4">four</option>
    <option value="5" selected="selected">five</option>
</select>

fixed and z-index

1. Explanation

• fixed is a type of positioning in html, which means it is suspended above the document flow

• absolute is absolute positioning in html, which means relative to the previous positioned element Absolute position, out of the document flow

• relative is relative positioning in HTML, which means the relative position relative to the upper level positioning element, not out of the document flow

• z-index is the priority, the priority of positioning, regardless of absolute/relative/fixed.

2. Usage scenarios

• When you want to click a button, the entire screen will be covered with a black mask, and a box will be displayed on top of the black mask. At this time, you can set their z-index value and positioning type

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