How to set css style for id

In the process of web design, the id selector is a common CSS selector, which can help developers more accurately select an element in the web page for style setting and modification.

First, we need to understand what an id selector is. In HTML, each element can use a unique id attribute to specify the unique identifier of the element. This unique identifier can be used by CSS to select and modify the style of the corresponding element. The id selector uses this unique identifier to select.

The syntax of the id selector is to add the "#" symbol before the selector name. For example, if you select a div element with the id attribute value of "main", you can write it as "#main". The specific usage method is also very simple. We only need to specify the id attribute value of the element that needs to be styled as the required unique identifier, and then use the corresponding id selector in the CSS file to select this element and set the style.

For example, we can add a div element with a unique id attribute in HTML:

<div id="main">这是一个主要的区域</div>

Then, use the id selector in the CSS file to style this element:

#main {
    background-color: #F0F0F0;
    color: #333;
    font-size: 18px;
}

In this way, you can set the background color of this element to gray, the font color to black, and the font size to 18px. We can further use the id selector to set other attributes of this element, such as setting the width, height, border, etc. of the element. The specific syntax of these style settings is beyond the scope of this article.

It should be noted that each id attribute can only be used once in the entire HTML file, otherwise the HTML document will be invalid. Therefore, when we need to apply the same style to multiple elements, instead of reusing the same id attribute value, we should use class selectors or other selectors.

In addition, pay attention to the priority of the id selector. If multiple style rules are set for the same element at the same time, the browser will decide which rule to use based on a certain priority. In CSS, the id selector has the highest priority, so it can override the styles set by other selectors. Therefore, when setting styles, be particularly careful and check carefully to avoid unnecessary errors.

To sum up, the id selector is a very common selector in CSS. It can be used to help developers select and set precise styles based on the unique identifier of the element. When using the id selector, we need to pay attention to the fact that the id attribute cannot be reused, pay attention to priority issues, etc., to ensure that the style settings are correct and effective.

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