HTML5’s new tag H5 attaches great importance to semantics
The block-level element has no width after it is floated, and you need to add width to it.
background:none;Clear the background image;
Positioning:
position(position):
static:static
fixed: Fixed positioning (changed relative to the browser) does not retain its own position
relative: Relative positioning (changed relative to itself) retains its own position, generally used together with absolute positioning.
absolute: Absolute positioning (changed relative to the parent element) does not retain its position,
left:20px/50%
top: 20px/50%
bottom:20px/50%
right:20px/50%
When an element is absolutely positioned, relative positioning must be set for its parent element.
When there are positioned relationship elements, there is a cascading relationship.
z-index: Set the cascading relationship
z-index:-0 1 2 3 ...99999 (the larger the value, the more it will be displayed on the upper layer)
Display mode of elements
display:block;/inline;/inline-block;/none
display:block The default display mode of block-level elements
display:inline The default display of inline elements Mode
display:inline-block The default display mode of inline block-level elements
display:none hides the label. Does not take up space
visibility:hidden Hide takes up space
Navigation drop-down menu production
Drop-down menu
<nav class="nav"> <ul> <li><a href="#">主页</a></li> <li><a href="#">新闻</a> <div> <p>本地</p> <p>国内</p> <p>国际</p> <p>政府</p> </div> </li> <li><a href="#">娱乐</a></li> <li><a href="#">军事</a></li> <li><a href="#">头条</a></li> </ul> </nav> li div{ display: none; position: absolute; background:darkgreen; } li:hover div{ display: block; } .nav ul{ position: relative; }
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