Can't vertical center h1 inside div

Question

I'm having some troubles when trying to vertical center a header inside a div. CSS is the following:

.container {
  background: #a3f;
  padding-left: 3% !important;
}

.container h4 {
  vertical-align: middle;
  text-align: center;
  background: #f02;
}

I have tried some solutions (also this), but the text continues at the top of the div.

Answer 1

Maybe using flexbox ?

.container {
  background: #a3f;
  padding-left: 3% !important;
  height: 500px;
  
  display:flex;
  justify-content:center;
  align-items:center;
}

.container h4 {
  /*vertical-align: middle;*/
  text-align: center;
  background: #f02;
}

<div class="container">
<h4>Blabla</h4>
</div>

Answer 2

There're several (5) methods from me:

1. grid (2 ways using grid)

.container {
  background: #a3f;
  height: 100px;
  
  display: grid;
  place-items: center;
  /* or */ /* place-content: center; */
}

.container h4 {
  background: #f02;
}

<div class="container">
  <h4> The header </h4>
</div>

2. flex

.container {
  background: #a3f;
  height: 100px;
  
  display: flex;
  justify-content: center;
  align-items: center;
}

.container h4 {
  background: #f02;
}

<div class="container">
  <h4> The header </h4>
</div>

3. translate(-50%, -50%)

.container {
  background: #a3f;
  height: 100px;
  position: relative;
}

.container h4 {
  background: #f02;
  
  position: absolute;
  left: 50%; top: 50%;
  margin: 0; padding: 0;
  -ms-transform: translate(-50%, -50%);
  transform    : translate(-50%, -50%);  
}

<div class="container">
  <h4> The header </h4>
</div>

4. table

.container {
  background: #a3f;
  height: 100px;
  
  width: 100%;
  display: table;
  text-align: center;
}

.container h4 {
  display: table-cell;
  vertical-align: middle;
}

<div class="container">
  <h4> The header </h4>
</div>

5. transform: translateY(-50%); with position: relative;

.container {
  background: #a3f;
  height: 100px;
  
}

.container h4 {
  background: #f02;
  
  text-align: center;
  position: relative;
  top: 50%;
  transform: translateY(-50%);
}

<div class="container">
  <h4> The header </h4>
</div>