The CSS ID selector matches an element based on the value of the element's id attribute. In order for the element to be selected, its id attribute must match exactly the value given in the selector.
css
/* The element with id="demo" */
#demo {
border: red 2px solid;
}
css
#id_value { style properties }
Note that syntactically (but not specificity-wise), this is equivalent to the following attribute selector:
css
[id=id_value] { style properties }
css
#identified {
background-color: skyblue;
}
html
<div id="identified">This div has a special ID on it!</div>
<div>This is just a regular div.</div>
| Specification |
|---|
| Selectors Level 4 # id-selectors |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
ID_selectors |
1 | 12 | 1 | 3 | 3.5 | 1 | ≤37 | 18 | 4 | 10.1 | 1 | 1.0 |
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https://developer.mozilla.org/en-US/docs/Web/CSS/ID_selectors