ID Selector

The CSS ID selector is used to style a single, unique element on a webpage. IDs are unique within a page, meaning each element should have only one ID.

Syntax

#idname {
    property: value;
}

Example

#header {
    background-color: black;
    color: white;
    padding: 20px;
    text-align: center;
}
/* Styling a unique button with the ID "submit-btn" */
#submit-btn {
    background-color: green;
    color: white;
    font-size: 16px;
}

Explanation

• #header applies styles only to the element with ID "header".
• #submit-btn applies styles only to the element with ID "submit-btn".

Example in HTML

<h1 id="header">Welcome to My Website</h1>
<button id="submit-btn">Submit</button>