⭐️ 有关 CSS Custom Properties 的学习
什么是Custom Properties CSS Custom Properties,也被称为CSS变量(Custom Properties),是CSS的一项功能,允许开发者定义并重用值。通过CSS变量,样式可以更加灵活和可维护。
- 可维护性:通过变量来管理颜色、字体等属性,更改时只需修改变量的值。
- 灵活性:可以在不同的上下文中重定义变量,实现多种主题或模式。
- 可读性:使用变量可以使CSS代码更加易读和理解。
定义和使用CSS变量
定义CSS变量
CSS变量使用--作为前缀,通常定义在:root选择器中,这样可以在整个文档中使用。例如:
:root { --primary-color: #3498db; --secondary-color: #2ecc71; --font-size: 16px; }
使用CSS变量
使用CSS变量时,采用var()函数。例如:
body {
color: var(--primary-color);
font-size: var(--font-size);
}
h1 {
color: var(--secondary-color);
}
示例:主题切换一
通过CSS变量,切换黑暗模式和白天模式变得非常简单。例如:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>主题切换</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<header>
<h1>我是标题</h1>
<label class="switch">
<input type="checkbox" id="toggleSwitch">
<span class="slider round"></span>
</label>
</header>
<main>
<p>请告诉我,我是什么颜色?</p>
</main>
<script src="script.js"></script>
</body>
</html>
/* style.css */
/* 定义CSS变量 */
:root {
--background-color: white;
--text-color: black;
--header-background-color: #f5f5f5;
}
body {
font-family: Arial, sans-serif;
background-color: var(--background-color);
color: var(--text-color);
transition: background-color 0.3s, color 0.3s;
}
body.dark-mode {
--background-color: #121212;
--text-color: white;
}
header {
display: flex;
justify-content: space-between;
align-items: center;
padding: 1rem;
background-color: var(--header-background-color);
}
.switch {
position: relative;
display: inline-block;
width: 60px;
height: 34px;
}
.switch input {
opacity: 0;
width: 0;
height: 0;
}
.slider {
position: absolute;
cursor: pointer;
top: 0;
left: 0;
right: 0;
bottom: 0;
background-color: #ccc;
transition: 0.4s;
border-radius: 34px;
}
.slider:before {
position: absolute;
content: "";
height: 26px;
width: 26px;
left: 4px;
bottom: 4px;
background-color: white;
transition: 0.4s;
border-radius: 50%;
}
input:checked + .slider {
background-color: #2196F3;
}
input:checked + .slider:before {
transform: translateX(26px);
}
// script.js
document.addEventListener('DOMContentLoaded', (event) => {
const toggleSwitch = document.getElementById('toggleSwitch');
const currentMode = localStorage.getItem('mode') || 'light';
document.body.classList.add(currentMode + '-mode');
if (currentMode === 'dark') {
toggleSwitch.checked = true;
}
toggleSwitch.addEventListener('change', () => {
const isDarkMode = toggleSwitch.checked;
document.body.classList.toggle('dark-mode', isDarkMode);
localStorage.setItem('mode', isDarkMode ? 'dark' : 'light');
});
});
示例:主题切换二
通过CSS变量,切换黑暗模式和白天模式变得非常简单。例如:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>主题切换</title>
<link rel="stylesheet" href="css/style.css">
</head>
<body>
<header>
<!-- <h1>我是标题</h1> -->
<label class="switch">
<input type="checkbox" id="toggleSwitch">
<span class="slider round"></span>
</label>
</header>
<main>
<div class="page">
<p>嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻嘻</p>
</div>
</main>
<script src="js/script.js"></script>
</body>
</html>
/* style.css */
/* 定义CSS变量 */
:root {
--background-color: white;
--text-color: black;
--header-background-color: #f5f5f5;
--page-background-color: #f5f5f5;
--box-shadow: 0 0px 10px -5px #949494;
}
body {
font-family: Arial, sans-serif;
background-color: var(--background-color);
color: var(--text-color);
transition: background-color 0.3s, color 0.3s;
}
body.dark-mode {
--background-color: #121212;
--text-color: white;
--header-background-color: #1d1e22;
--page-background-color: #1d1e22;
}
header {
display: flex;
justify-content: space-between;
align-items: center;
padding: 1rem;
border-radius: 10px;
background-color: var(--header-background-color);
}
.page{
margin-top: 1rem;
padding: 1rem;
border-radius: 10px;
background-color: var(--page-background-color);
}
.switch {
position: relative;
display: inline-block;
width: 60px;
height: 34px;
}
.switch input {
opacity: 0;
width: 0;
height: 0;
}
.slider {
position: absolute;
cursor: pointer;
top: 0;
left: 0;
right: 0;
bottom: 0;
background-color: #ccc;
transition: 0.4s;
border-radius: 34px;
}
.slider:before {
position: absolute;
content: "";
height: 26px;
width: 26px;
left: 4px;
bottom: 4px;
background-color: white;
transition: 0.4s;
border-radius: 50%;
}
input:checked + .slider {
background-color: #2196F3;
}
input:checked + .slider:before {
transform: translateX(26px);
}
// script.js
document.addEventListener('DOMContentLoaded', (event) => {
const toggleSwitch = document.getElementById('toggleSwitch');
const currentMode = localStorage.getItem('mode') || 'light';
document.body.classList.add(currentMode + '-mode');
if (currentMode === 'dark') {
toggleSwitch.checked = true;
}
toggleSwitch.addEventListener('change', () => {
const isDarkMode = toggleSwitch.checked;
document.body.classList.toggle('dark-mode', isDarkMode);
localStorage.setItem('mode', isDarkMode ? 'dark' : 'light');
});
});