How to modify CSS styles correctly

CSS (Cascading Style Sheets) is an important part of front-end development. CSS can control the appearance and layout of web pages. In the daily development process, we often need to modify CSS to achieve the effects we want. How to modify CSS correctly? Let me talk about my views below.

First of all, we need to know the basic syntax of CSS. CSS consists of attributes and values. You use a selector to select a tag or tag group, and then set the attributes and corresponding values ​​for the tag or tag group. Attributes generally have default values. When we need to modify an attribute, we can first check the default value of the attribute, then confirm the new value we want before modifying it, and test the new value. If you are not sure about the default value of a property, you can get it by querying the documentation or using Google.

Secondly, we need to understand the priority rules of CSS. When multiple CSS styles are applied to an element at the same time, priority rules are needed to determine which style will ultimately be applied. The order of precedence in CSS is: !important > inline styles > ID > classes, pseudo-classes, properties > tags > wildcards > inheritance. Therefore, if we need to modify the style of an element, it is best to use ID, class or attribute selectors first.

In addition, there are some common techniques and precautions for CSS. For example, using CSS abbreviation syntax can make CSS code more concise and readable. For example, we can abbreviate border-width: 2px; border-style: solid; border-color: #ccc; to border: 2px solid #ccc;. We can also use CSS preprocessors such as Sass and Less to simplify the writing and maintenance of CSS code. In addition, in order to avoid code conflicts and increase code maintainability, we can define independent class names or IDs for different modules, and use clear and understandable naming rules for these class names or IDs.

Finally, we need to pay attention to CSS compatibility issues. Different browsers or devices may have different levels of support for CSS, so you need to take these factors into consideration when making CSS modifications. We can solve compatibility issues through some tools or frameworks. For example, using the CSS framework Bootstrap can avoid most compatibility issues. At the same time, we can use some preprocessors such as Autoprefixer to automatically add CSS compatibility prefixes to adapt to various browsers.

To sum up, although CSS modification seems simple, there are actually many factors that need to be considered. Only by understanding the basic syntax, priority rules, precautions and compatibility issues of CSS can we modify CSS correctly and achieve the effects we want.

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