CSS - max-width 屬性

CSS 的 max-width 屬性設定元素的最大寬度。如果元素的寬度超過最大寬度，則元素的高度會增加。如果內容完全適合元素的最大寬度，則不會產生任何效果。

語法

max-width: none | length | percentage | initial | inherit;

屬性值

值	描述
none	不設定元素寬度的限制。預設值。
length	使用長度單位（例如 px、em、rem 等）設定元素的最大寬度。
percentage	使用百分比值（例如 10%）相對於容器大小設定元素的最大寬度。
initial	將屬性設定為其預設值。
inherit	從父元素繼承該屬性。

CSS Max Width 屬性示例

以下示例說明了使用不同值的 max-width 屬性。

使用 None 值的 Max Width 屬性

為了不設定元素寬度的任何限制，我們可以使用 none 值。定義的寬度將應用於元素。這在以下示例中顯示。

示例

<!DOCTYPE html>
<html>
<head>
   <style>
      .container {
         width: 300px;
         height: 120px;
         padding: 5px;
         max-width: none;
         background-color: lightgreen;
      }
   </style>
</head>
<body>
   <h2>
      CSS max-width property
   </h2>
   <h4>
      max-width: none (the defined width 
      value will be applied)
   </h4>
   <div class="container">
      TutorialsPoint is an online platform offering free 
      tutorials and resources on various topics including 
      programming, web development, and data science. It 
      provides structured lessons, examples, and quizzes 
      for effective learning.
   </div>
</body>
</html>

使用長度值的 Max Width 屬性

為了設定元素寬度的最大限制，我們可以使用長度單位（例如 px、em、rem 等）指定最大寬度值。這在以下示例中顯示。

示例

<!DOCTYPE html>
<html>
<head>
   <style>
      .container {
         width: 300px;
         height: 120px;
         padding: 5px;
         background-color: lightgreen;
      }

      .ex1 {
         max-width: 200px;
      }

      .ex2 {
         max-width: 250px;
      }
   </style>
</head>
<body>
   <h2>
      CSS max-width property
   </h2>
   <h4>
      max-width: 200px (the maximum width is 200px, 
      if content is larger, the height will increase.)
   </h4>
   <div class="container ex1">
      TutorialsPoint is an online platform offering free 
      tutorials and resources on various topics including 
      programming, web development, and data science. It 
      provides structured lessons, examples, and quizzes 
      for effective learning.
   </div>
   <br/>
   <h4>
      max-width: 250px (the maximum width is 250px, 
      in the following example content is not greater 
      than the width, so no height change occurs.)
   </h4>
   <div class="container ex2">
      TutorialsPoint is an online platform offering free 
      tutorials and resources on various topics including 
      programming, web development, and data science. It 
      provides structured lessons, examples, and quizzes 
      for effective learning.
   </div>
</body>
</html>

使用百分比值的 Max Width 屬性

為了設定元素寬度的最大限制，我們可以使用百分比值（例如 10%）相對於包含元素的大小指定最大寬度值。這在以下示例中顯示。

示例

<!DOCTYPE html>
<html>
<head>
   <style>
      .outer-container {
         width: 400px;
         height: 180px;
         padding: 5px;
      }

      .inner-container {
         width: 100%;
         width: 100%;
         position: relative;
      }

      .color {
         background-color: lightgreen;
      }

      .ex1 {
         max-width: 40%;
      }

      .ex2 {
         max-width: 90%;
      }
   </style>
</head>
<body>
   <h2>
      CSS max-width property
   </h2>
   <h4>
      max-width: 55% (the maximum width is 55% of the 
      inner-container's width, height increases, if 
      content is larger than the max-width as in this case.)
   </h4>
   <div class="outer-container">
      <div class="inner-container">
         <div class="ex1 color">
            TutorialsPoint is an online platform offering free 
            tutorials and resources on various topics including 
            programming, web development, and data science. It 
            provides structured lessons, examples, and quizzes 
            for effective learning.
         </div>
      </div>
   </div>
   <br/>
   <h4>
      max-width: 90% (the maximum width is 90% of the 
      inner-container's width, height does not increase 
      as max-width accomodates all the content)
   </h4>
   <div class="outer-container">
      <div class="inner-container">
         <div class="ex2 color">
            TutorialsPoint is an online platform offering free 
            tutorials and resources on various topics including 
            programming, web development, and data science. It 
            provides structured lessons, examples, and quizzes 
            for effective learning.
         </div>
      </div>
   </div>
</body>
</html>

支援的瀏覽器

屬性
max-width	1.0	7.0	1.0	2.0.2	7.0

css_properties_reference.htm

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