background-attachment

background-attachment 這個 CSS 屬性能夠設定，背景圖片的位置是否要固定在 viewport（視圖）上，還是背景圖片會隨著它的 containing block（外層容器）一起滾動。

嘗試一下

語法

css
/* Keyword values */
background-attachment: scroll;
background-attachment: fixed;
background-attachment: local;

/* Global values */
background-attachment: inherit;
background-attachment: initial;
background-attachment: unset;

background-attachment 屬性的值，可以是下方清單中的其中之一。

Values

fixed

讓背景相對於 viewport（視圖）的移動是固定的。即便元素中的內容是可滾動的，背景也不會在滾動元素內容時跟著移動。(這個屬性與 background-clip: text (en-US) 不相容。)

local

讓背景相對於元素的內容是固定的，且背景在滾動元素的內容時會跟著移動。另外，背景的繪製與定位區域是相對於元素的可滾動區域，而不是包裹著它們的邊框。

scroll

讓背景相對於元素本身是固定的，使背景在滾動元素的內容時不會跟著移動。（It is effectively attached to the element's border.）

Formal syntax

background-attachment = 
  <attachment># (en-US)  

<attachment> = 
  scroll  | (en-US)
  fixed   | (en-US)
  local

例子

Simple example

HTML

html
<p>
  There were doors all round the hall, but they were all locked; and when Alice
  had been all the way down one side and up the other, trying every door, she
  walked sadly down the middle, wondering how she was ever to get out again.
</p>

CSS

css
p {
  background-image: url("starsolid.gif");
  background-attachment: fixed;
}

Result

Multiple background images

這個屬性支援多個背景圖片。你可以對每個背景設定不同的 <attachment>。每個背景圖片會依序對應在 <attachment> 設定的類型。

HTML

html
<p>
  There were doors all round the hall, but they were all locked; and when Alice
  had been all the way down one side and up the other, trying every door, she
  walked sadly down the middle, wondering how she was ever to get out again.
  Suddenly she came upon a little three-legged table, all made of solid glass;
  there was nothing on it except a tiny golden key, and Alice's first thought
  was that it might belong to one of the doors of the hall; but, alas! either
  the locks were too large, or the key was too small, but at any rate it would
  not open any of them. However, on the second time round, she came upon a low
  curtain she had not noticed before, and behind it was a little door about
  fifteen inches high: she tried the little golden key in the lock, and to her
  great delight it fitted!
</p>

CSS

css
p {
  background-image: url("starsolid.gif"), url("startransparent.gif");
  background-attachment: fixed, scroll;
  background-repeat: no-repeat, repeat-y;
}

Result

Specifications

Specification
CSS Backgrounds and Borders Module Level 3
# the-background-attachment
預設值 (en-US)scroll
Applies toall elements. It also applies to ::first-letter and ::first-line (en-US).
繼承與否no
Computed value (en-US)as specified
Animation type (en-US)discrete

Browser compatibility

BCD tables only load in the browser

See also