How to center an element horizontally and vertically

Do you still think centering in CSS is hard? Find below 100 different methods to center a single element inside a container.

<div class="container">
  <div class="item">Content</div>
</div>

Many of the methods are hacky and not recommended, but it's funny to illustrate all the possible ways to center an element.
Have fun and avoid using the red codes!

.container {
  display: grid;
  place-content: center;
}

.container {
  display: grid;
  place-content: space-around;
}

.container {
  display: grid;
  place-content: space-evenly;
}

.container {
  display: grid;
  place-items: center;
}

.container {
  display: grid;
}
.item {
  place-self: center;
}

.container {
  display: grid;
}
.item {
  margin: auto;
}

.container {
  display: grid;
  grid: 1fr auto 1fr/1fr auto 1fr;
}
.item {
  grid-area: 2/2;
}

.container {
  display: grid;
  grid: 
    1fr [x] auto [x] 1fr/
    1fr [x] auto [x] 1fr;
}
.item {
  grid-area: x;
}

.container {
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  display: flex;
  align-items: center;
  justify-content: space-around;
}

.container {
  display: flex;
  align-items: center;
  justify-content: space-evenly;
}

.container {
  display: flex;
  flex-wrap: wrap;
  place-content: center;
}

.container {
  display: flex;
  flex-wrap: wrap;
  place-content: space-around;
}

.container {
  display: flex;
  flex-wrap: wrap;
  place-content: space-evenly;
}

.container {
  display: flex;
}
.item {
  margin: auto;
}

.container {
  display: flex;
  justify-content: center;
}
.item {
  align-self: center;
}

.container {
  display: flex;
  justify-content: space-around;
}
.item {
  align-self: center;
}

.container {
  display: flex;
  justify-content: space-evenly;
}
.item {
  align-self: center;
}

.container {
  display: flex;
  align-items: center;
}
.container:before,
.container:after {
  content: "";
  flex: 1;
}

.container {
  display: flex;
}
.container:before,
.container:after {
  content: "";
  flex: 1;
}
.item {
  align-self: center;
}

.container {
  display: block;
  align-content: center;
  justify-items: center;
}

.container {
  display: block;
  align-content: space-around;
  justify-items: center;
}

.container {
  display: block;
  align-content: space-evenly;
  justify-items: center;
}

.container {
  display: block;
  align-content: center;
}
.item {
  justify-self: center;
}

.container {
  display: block;
  align-content: space-around;
}
.item {
  justify-self: center;
}

.container {
  display: block;
  align-content: space-evenly;
}
.item {
  justify-self: center;
}

.container {
  display: block;
  align-content: center;
}
.item {
  width: fit-content;
  margin: auto;
}

.container {
  display: block;
  align-content: center;
}
.item {
  max-width: max-content;
  margin: auto;
}

.container {
  display: block;
  align-content: center;
  text-align: center;
}
.item {
  display: inline-block;
}

.container {
  display: block;
  align-content: center;
}
.item {
  display: table;
  margin: auto;
}

.container {
  display: block;
  text-align: center;
}
.item {
  position: relative;
  top: 50%;
  translate: 0 -50%;
  display: inline-block;
}

.container {
  display: block;
}
.item {
  position: relative;
  top: 50%;
  translate: 0 -50%;
  width: fit-content;
  margin: auto;
}

.container {
  display: block;
}
.item {
  position: relative;
  top: 50%;
  translate: 0 -50%;
  max-width: max-content;
  margin: auto;
}

.container {
  display: block;
}
.item {
  position: relative;
  top: 50%;
  translate: 0 -50%;
  display: table;
  margin: auto;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  left: 50%;
  translate: -50%;
  display: inline-block;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  left: 50%;
  translate: -50%;
  display: table;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  left: 50%;
  translate: -50%;
  width: fit-content;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  left: 50%;
  translate: -50%;
  max-width: max-content;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  left: 50%;
  translate: -50%;
  float: left;
}

.container {
  display: block;
  align-content: center;
}
.item {
  position: relative;
  right: 50%;
  translate: 50%;
  float: right;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 0 0 50%;
  translate: -50% -50%;
  display: inline-block;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 0 0 50%;
  translate: -50% -50%;
  display: table;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 0 0 50%;
  translate: -50% -50%;
  width: fit-content;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 0 0 50%;
  translate: -50% -50%;
  max-width: max-content;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 0 0 50%;
  translate: -50% -50%;
  float: left;
}

.container {
  display: block;
}
.item {
  position: relative;
  inset: 50% 50% 0 auto;
  translate: 50% -50%;
  float: right;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 0;
  place-self: center;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 0;
  width: fit-content;
  height: fit-content;
  margin: auto;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 0;
  max-width: max-content;
  max-height: max-content;
  margin: auto;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 50% auto auto 50%;
  translate: -50% -50%;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: auto auto 50% 50%;
  translate: -50% 50%;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 50% 50% auto auto;
  translate: 50% -50%;
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: auto 50% 50% auto;
  translate: 50% 50%;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 0;
  place-self: center;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 0;
  width: fit-content;
  height: fit-content;
  margin: auto;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 0;
  max-width: max-content;
  max-height: max-content;
  margin: auto;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 50% auto auto 50%;
  translate: -50% -50%;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: auto auto 50% 50%;
  translate: -50% 50%;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 50% 50% auto auto;
  translate: 50% -50%;
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: auto 50% 50% auto;
  translate: 50% 50%;
}

.container {
  display: block;
  container-type: size;
  text-align: center;
}
.container:before {
  content: "";
  line-height: 100cqb;
}
.item {
  display: inline-block;
}

.container {
  display: block;
  container-type: size;
  text-align: center;
}
.container:before {
  content: "";
  display: inline-block;
  height: 100cqb;
  vertical-align: middle;
}
.item {
  display: inline-block;
}

.container {
  display: block;
  container-type: size;
}
.item {
  margin: 50cqb 0 0 50%;
  translate: -50% -50%;
  display: inline-block;
}

.container {
  display: block;
  container-type: size;
}
.item {
  margin: 50cqb 0 0 50%;
  translate: -50% -50%;
  width: fit-content;
}

.container {
  display: block;
  container-type: size;
}
.item {
  margin: 50cqb 0 0 50%;
  translate: -50% -50%;
  float: left;
}

.container {
  display: block;
  container-type: size;
}
.item {
  margin: 50cqb 50% 0 0;
  translate: 50% -50%;
  float: right;
}

.container {
  display: block;
  container-type: size;
}
.item {
  display: inline-block;
  translate: 
    calc(50cqi - 50%) 
    calc(50cqb - 50%);
}

.container {
  display: block;
  container-type: size;
}
.item {
  width: fit-content;
  translate: 
    calc(50cqi - 50%) 
    calc(50cqb - 50%);
}

.container {
  display: block;
  container-type: size;
}
.item {
  float: left;
  translate: 
    calc(50cqi - 50%) 
    calc(50cqb - 50%);
}

.container {
  display: block;
  container-type: size;
}
.item {
  float: right;
  translate: 
    calc(50% - 50cqi) 
    calc(50cqb - 50%);
}

.container {
  position: relative;
  container-type: size;
}
.item {
  position: absolute;
  translate: 
    calc(50cqi - 50%) 
    calc(50cqb - 50%);
}

.container {
  contain: layout;
  container-type: size;
}
.item {
  position: fixed;
  translate: 
    calc(50cqi - 50%) 
    calc(50cqb - 50%);
}

Starting from here, I may consider fixed values for the width/height of the item (200px x 100px).

.container {
  display: block;
  align-content: center;
}
.item {
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
  align-content: space-around;
}
.item {
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
  align-content: space-evenly;
}
.item {
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
}
.item {
  position: relative;
  height: 100px;
  top: calc(50% - 100px/2);
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
}
.item {
  position: relative;
  height: 100px;
  width:  200px;
  inset: 
    calc(50% - 100px/2) 0
    0 calc(50% - 200px/2);
}

.container {
  display: block;
  container-type: size;
}
.item {
  height: 100px;
  margin: 
    max(0px,50cqb - 100px/2) 
    max(0px,50%   - 200px/2);
}

.container {
  display: block;
  container-type: size;
}
.item {
  height: stretch;
  margin: 
    max(0px,50cqb - 100px/2) 
    max(0px,50%   - 200px/2);
}

.container {
  position: relative;
}
.item {
  position: absolute;
  inset: 
    calc(50% - 100px/2) 
    calc(50% - 200px/2);
}

.container {
  contain: layout;
}
.item {
  position: fixed;
  inset: 
    calc(50% - 100px/2) 
    calc(50% - 200px/2);
}

Starting from here, I will consider the height of the container to be a known and fixed value (300px).

.container {
  display: block;
  line-height: 300px;
  text-align: center;
}
.item {
  display: inline-block;
  line-height: initial;
}

.container {
  display: block;
  text-align: center;
}
.container:before {
  content: "";
  line-height: 300px;
}
.item {
  display: inline-block;
}

.container {
  display: block;
  text-align: center;
}
.container:before {
  content: "";
  height: 300px;
  display: inline-block;
  vertical-align: middle;
}
.item {
  display: inline-block;
}

.container {
  display: block;
  height: 300px;
}
.container:before {
  content: "";
  display: block;
  height: calc(50% - 100px/2);
}
.item {
  height: 100px;
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
}
.container:before,
.container:after {
  content: "";
  display: block;
  height: calc((300px - 100px)/2);
}
.item {
  height: 100px;
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
  box-sizing: border-box;
  padding-block: calc((300px - 100px)/2);
}
.item {
  height: 100px;
  margin: 0 max(0px,50% - 200px/2);
}

.container {
  display: block;
}
.item {
  height: 100px;
  margin: 
    calc((300px - 100px)/2) 
    max(0px,50% - 200px/2);
}

.container {
  display: block;
  height: 300px;
}
.item {
  position: relative;
  height: 100px;
  width:  200px;
  inset: 
    calc((300px - 100px)/2) 0
    0 calc(50% - 200px/2);
}

Starting from here, I will consider the width of the container to be a known and fixed value (400px).

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  width: fit-content;
  margin: auto;
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  display: table;
  margin: auto;
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
  text-align: center;
}
.item {
  display: inline-block;
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  width: fit-content;
  translate: calc(400px/2 - 50%);
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  display: inline-block;
  translate: calc(400px/2 - 50%);
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  display: table;
  translate: calc(400px/2 - 50%);
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  float: left;
  translate: calc(400px/2 - 50%);
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
}
.item {
  float: right;
  translate: calc(50% - 400px/2);
}

.container {
  display: table-cell;
  width: 400px;
  vertical-align: middle;
  box-sizing: border-box;
  padding: 0 calc((400px - 200px)/2);
}

.container {
  display: inline-block;
  align-content: center;
  padding: 0 calc((400px - 200px)/2);
}
.item {
  width: 200px;
}

.container {
  display: inline-block;
  padding: 
    calc((300px - 100px)/2) 
    calc((400px - 200px)/2);
}
.item {
  height: 100px;
  width:  200px;
}

I didn't consider all the possible combinations, yet I was still able to reach 100 different codes.
Let's stop here, and don't use the red codes!