CSS背景大小的一個參數

Question

我試圖讓HTML/CSS一個更好的把握，很多時候我看到這樣 background-size: 100px

的東西是什麼意思時，有東西給只有一個參數要求長度和寬度？它是否默認僅根據圖像定義長度和縮放寬度？還是默認爲寬度？

Answer 1

如果只定義了一種尺寸，則將其作爲寬度處理，高度自動設置爲auto。

從the Mozilla Developer Network：

/* Keywords syntax */ 
background-size: cover 
background-size: contain 

/* One-value syntax: the value defines the width of the image, the height is implicitly set to 'auto' */ 
background-size: 50% 
background-size: 3em 
background-size: 12px 
background-size: auto 

/* Two-value syntax: the first value defines the width of the image, the second its height */ 
background-size: 50% auto 
background-size: 3em 25% 
background-size: auto 6px 
background-size: auto auto 

/* Values for the multiple backgrounds, defined by background-image, may be listed separated by commas */ 
background-size: auto, auto  /* Do not confuse this with background-size: auto auto */ 
background-size: 50%, 25%, 25% 
background-size: 6px, auto, contain 

background-size: inherit