css, side by side, progeny and property of the application

A tag selector written directly span {} div {}, etc.
2 id selector style in the unique symbol is #, the value of the format #id
3 class selector may be repeated, symbols, format .class value.
4 meet the selector:
parallel : it can be used in conjunction .class1, .class2, # ID1, ID2 # {}
.class value 1, class 2 {value} style
#id value 1, id value {2}
progeny: writing:. id selector or selection name label
filter: class selector
properties: syntax: tag name [attribute = "attribute value"] {style}
INPUT [nmae = "NAME1"] {width: 10px;}

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# demo10 {
/ * width: 100px;
height: 100px; * /
border: 1px Solid Red;
}
/ * offspring usage, only take effect * / for demo10 offspring
# demo10 span {
border: 1px Solid Red;
}
/ * only demo10 under the effective span of demo10 invalid * /
INPUT [name = "Nam"] {
width: 500px;
}

<input type="text" name="nam">
<input type="text" name="name2">
<input type="text" name="name3">
<input type="text" name="name4">
<input type="text" name="nam">

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<div id="demo10">
<span style="width:100px;height:100px;">后代的用法</span><br>

<span> span tag set according to the aspect SUMMARY </ span>
</ div>