背景图无法缩小问题求助：容器尺寸改变但背景图大小不变

初始效果：

HTML代码 #

<div class="lb-controlContainer">
<div class="lb-closeContainer">
<a class="lb-close"></a>
</div>
<div class="lb-downloadContainer" hidden="">
<a class="lb-download"></a></div><div class="lb-turnContainer" hidden="">
<a class="lb-turnLeft"></a><a class="lb-turnRight"></a>
</div>
<div class="lb-zoomContainer">
<a class="lb-zoomOut"></a>
<a class="lb-zoomIn"></a>
</div></div>

CSS代码 #

.lb-data .lb-zoomOut {
    display: block;
    float: left;
    width: 30px;
    height: 30px;
    background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAB4AAAAeCAYAAAA7MK6iAAAABmJLR0QA/wD/AP+gvaeTAAAB7UlEQVRIieXWvWsUURTG4XPjJpgmlSFKRAtTWGjAj0ajiSKKFopg/AtELbQTAiI2IaazEhsLK0XEVisbISD4gY2FlQQixiAYxESiBn0sdoKTQHZ3dte18FR3uO97fufcmbmciH8UqVYhUkT0RER3RMxGxMeU0uJfqQoJJ/EAc5bHDzzGWXQ0E9qPZ/iMGziCXnRgPfZgDFN4i2PNgJ7IOryFdVW0a3EZ3zHSCHQfvuFCQd8hzONcPdAuzGC0sLnsP5UVvb2o8RpeY0094CzHXTwqYmjHLIbrhWZ5tuAX+mo1LL2jzkbAWa4XuFRJ05Zb74iIlymlhUbBETERETsrCUq59YaImM5vYlNEXKkBdCelNJF7fh/lRlaNtkqbDUbF6zjf8YeI2LXMmdJURJyvA9obETOVBPmOX0XE7mZ8XBExGBHPa1KihE843QgRffiJrUVMo3iDUnX1qjnu4WFRUxemMVYndBgLha/MzLw3M18s6DucXUDXC0NzSY7jC26ju4q2E1exmA0I8xhqBL4NT7MCbuIoNuYGgQGM4x0mMZJBmwJP2VBwPysgHwt4gjNLvyCGVsAH64avKKRHeSTabJU5awV8rmnwGgscyJ3QVxz8b+EHWgnf789MPon2VsIHlGfv/pZBc/DWdVopfgMdyEl3/DM14wAAAABJRU5ErkJggg==) top right no-repeat;
    text-align: right;
    outline: none;
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=70);
    opacity: 0.7;
    transition: opacity 0.2s;
}

.lb-data .lb-close {
    display: block;
    float: right;
    width: 20px;
    height: 20px;
    background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAMAAAC6CgRnAAAAPFBMVEX///8AAAD9/f2CgoKAgIAAAAAAAAAAAABLS0sAAAAAAACqqqqqqqq6urpKSkpISEgAAAC7u7u5ubn////zbsMcAAAAE3RSTlMASv6rqwAWS5YMC7/AyZWVFcrJCYaKfAAAAHhJREFUeF590kkOgCAQRFEaFVGc+/53FYmbz6JqBbyQMFSYuoQuV+iTflnstI7ssLXRvMWRaEMs84e2uVckuZe6knL0hiSPObXhj6ChzoEkIolIIpKIO4joICAIeDd7QGIfCCjOKe9HEk8mnxpIAup/F31RPZP9fAG3IAyBSJe0igAAAABJRU5ErkJggg==) top right no-repeat;
    text-align: right;
    outline: none;
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=70);
    opacity: 0.7;
    transition: opacity 0.2s;
}

修改按钮尺寸为width:10px;height:15px后：

实际显示效果：

容器尺寸已改变，但背景图大小仍保持不变，该如何解决？

问题核心是默认情况下背景图会保持原始尺寸，不会自动适配容器。只需在CSS中添加background-size属性，让背景图跟随容器缩放即可。

调整后的CSS示例 #

针对目标类修改背景配置：

.lb-data .lb-zoomOut {
    display: block;
    float: left;
    width: 10px;
    height: 15px;
    background: url(data:image/png;base64,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) top right no-repeat;
    /* 添加background-size属性适配容器 */
    background-size: 100% 100%;
    text-align: right;
    outline: none;
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=70);
    opacity: 0.7;
    transition: opacity 0.2s;
}

.lb-data .lb-close {
    display: block;
    float: right;
    width: 10px;
    height: 15px;
    background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAMAAAC6CgRnAAAAPFBMVEX///8AAAD9/f2CgoKAgIAAAAAAAAAAAABLS0sAAAAAAACqqqqqqqq6urpKSkpISEgAAAC7u7u5ubn////zbsMcAAAAE3RSTlMASv6rqwAWS5YMC7/AyZWVFcrJCYaKfAAAAHhJREFUeF590kkOgCAQRFEaFVGc+/53FYmbz6JqBbyQMFSYuoQuV+iTflnstI7ssLXRvMWRaEMs84e2uVckuZe6knL0hiSPObXhj6ChzoEkIolIIpKIO4joICAIeDd7QGIfCCjOKe9HEk8mnxpIAup/F31RPZP9fAG3IAyBSJe0igAAAABJRU5ErkJggg==) top right no-repeat;
    background-size: 100% 100%;
    text-align: right;
    outline: none;
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=70);
    opacity: 0.7;
    transition: opacity 0.2s;
}

可选的background-size取值 #

• 100% 100%：背景图拉伸填满容器，可能会变形
• cover：背景图等比缩放覆盖容器，超出部分被裁剪
• contain：背景图等比缩放完整显示，容器可能留空白
• 具体数值（如8px 12px）：直接指定背景图宽高

根据视觉需求选择合适取值即可。

内容的提问来源于stack exchange，提问作者user3653474