March 1Mar 1 Administrators CSS The z-index Property The CSS z-index Property The z-index property specifies the stack order of positioned elements. The stack order defines which element should be placed in front or behind other elements. When elements are positioned, they can overlap other elements. An element can have a positive or negative stack order (z-index): This is a heading Because the image has a z-index of -1, it will be placed behind the text. Example img { position: absolute; left: 0px; top: 0px; z-index: -1; } Try it Yourself » Note: z-index only works on positioned elements (position: absolute, position: relative, position: fixed, or position: sticky) and flex items (elements that are direct children of display: flex elements). Another z-index Example A postioned element with a greater stack order is always above an element with a lower stack order. Example <html><head><style>.container { position: relative;} .black-box { position: relative; z-index: 1; border: 2px solid black; height: 100px; margin: 30px;}.gray-box { position: absolute; z-index: 3; background: lightgray; height: 60px; width: 70%; left: 50px; top: 50px;}.green-box { position: absolute; z-index: 2; background: lightgreen; width: 35%; left: 270px; top: -15px; height: 100px;}</style></head><body> <div class="container"> <div class="black-box">Black box</div> <div class="gray-box">Gray box</div> <div class="green-box">Green box</div></div></body></html> Try it Yourself » Without z-index If several positioned elements overlap each other without a z-index specified, the elements render in the order they are defined in the HTML source code. Example Same example as above, but here with no z-index specified: <html><head><style>.container { position: relative;} .black-box { position: relative; border: 2px solid black; height: 100px; margin: 30px;}.gray-box { position: absolute; background: lightgray; height: 60px; width: 70%; left: 50px; top: 50px;}.green-box { position: absolute; background: lightgreen; width: 35%; left: 270px; top: -15px; height: 100px;}</style></head><body> <div class="container"> <div class="black-box">Black box</div> <div class="gray-box">Gray box</div> <div class="green-box">Green box</div></div></body></html> Try it Yourself » CSS Property Property Description z-index Sets the stack order of an element ★ +1 Sign in to track progress
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