1.javascript+css+div Implementation drop-down menu
1.1 Layer Label <div>
Basic syntax:
<div id= "layer number" style= "POSITION:ABSOULT;LEFT:29PX;TOP:12PX;
Width:200px;henght:100px;background-color: #33CC99;
Float:none;clear:none;z-index:1 ">
</div>
Syntax Description:
The position attribute is mainly to define the positioning method of the layer;
left and top are the positions used to position the layer, representing the relative position of the left and top of other objects.
width and length are used to define the width and height of the layer.
float is a floating property of the layer that is used to set the floating position of the layer.
Clear is a layer's Purge property that indicates whether a floating element is allowed around an element, he and the floating
property is an opposing property, The Float property is used to set the floating position of an element, while clearing the property
You want to remove the floating element from a position.
Z-index is mainly to set up the upper and lower relations of the area, and this property can be used to set the effect of the region more layers.
The z-coordinate of a fairly 13-dimensional space, the larger the Z-index coordinate, the higher the area's position in the heap
2017.9.24 HTML+JAVASCRIPT+CSS-based development case &&javascript+css+div realizing table discoloration