way1:
flex layout: main axis vertically centered + side axis vertically centered
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
margin: 100px auto 0;
display: flex;
justify-content: center;
align-items: center;
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
}
</style>
<body>
<div class="bigBox">
<div class="smallBox"></div>
</div>
</body>
way2:
Parent: relative positioning
Child level: Absolute positioning, top, bottom, left, and right 0 + margin:auto
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
margin: 100px auto 0;
position: relative;
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
position: absolute;
margin: auto;
top: 0;
bottom: 0;
right: 0;
left: 0;
}
</style>
way3:
Child level: top and left margin = 50% of (parent box width/height - box width/height) (need to be calculated)
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
margin: 100px auto 0;
overflow: hidden;
/* padding-top: 50px; */
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
margin-top: 50px;
margin-left: 50px;
}
</style>
way4:
Parent: relative positioning
Child level: absolute positioning + 50% from the upper left of the parent box, and then move back 50% of its own width and height (need to calculate)
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
margin: 100px auto 0;
position: relative;
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
position: absolute;
top: 50%;
left: 50%;
margin-top: -100px;
margin-left: -100px;
}
</style>
way5:
Parent: relative positioning
Child level: Absolute positioning + 50% from the upper left of the parent box, and then move 50% of itself on the x and y axes
(No need to calculate, use displacement directly)
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
margin: 100px auto 0;
position: relative;
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
</style>
way6:
Parent: display: table-cell + baseline alignment + text center alignment
Child: Wrapped Inline Block
Note: The display:table-cell attribute is very similar to the td tag, and has no meaning for the margin value
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.bigBox {
width: 300px;
height: 300px;
background-color: plum;
/* margin: 100px auto 0; */
display: table-cell;
vertical-align: middle;
text-align: center;
}
.smallBox {
width: 200px;
height: 200px;
background-color: yellowgreen;
display: inline-block;
}
</style>