背景图片填充div

html:
<div class=”contain-title”><div>

css:
(1)这种情况下图片可以填充整个div，但背景色和原背景图片不一致
background: url(../images/mall-bg.png) no-repeat center center fixed;
height: 11.5rem;
width: 100%;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
display: flex;
justify-content: space-around;
align-items: center;

（2）和背景图片基本一致，但背景图片在宽度上没有填充整个div，左右两边有间距
background: url(../images/mall-bg.png);
background-size: 100%;
height: 9rem;

（3）背景图片在宽度上填充整个div，且基本与原背景图片效果一致
width: 100%;
display: flex;
justify-content: space-around;
align-items: center;
background: url(../images/mall-bg.png);
height: 9rem;
background-position: center;
background-size: 110% 100%;