Why div containing img does not stretch his parent's div height - html

Question

I wonder why mainCountainerHeadLogo does not stretch parent div mainCountainerHead height?
If I scale the page, both mainCountainerHeadTitle and mainCountainerHeadMenu stretch mainCountainerHead just fine.
Sorry for my english and thanks in advance!
http://jsfiddle.net/gvcs0r6b/
* {
margin: 0;
padding: 0;
}
html, body {
height: 100%;
}
.mainCountainer {
min-height: 100%;
width: 70%;
margin: 0 auto;
}
.mainCountainerHead {
background-color: aqua;
height: auto;
}
.mainCountainerHeadLogo {
height: 100px;
width: 20%;
background-color: blue;
float: left;
position: relative;
overflow: hidden;
}
.mainCountainerHeadLogo img {
position: absolute;
width: 100%;
height: auto;
top: -50%;
right: -50%;
bottom: -50%;
left: -50%;
margin: auto
}
.mainCountainerHeadTitle{
margin-left: 20%;
width: 80%;
height: auto;
text-align: center;
padding-top: 3%;
}
.mainCountainerHeadMenu{
margin-left: 20%;
text-align: center;
background-color: orange;
width: 80%;
height: auto;
padding-top: 2%;
text-align: center;
}
.mainLink {
display: inline-block;
padding: 5px;
}
.mainLinkButton {
width: 90px;
height: 30px;
background-color: green;
font-size: 16px;
border: none;
color: white;
padding: 5px;
}
.mainLinkButton:hover {
background-color: darkgreen;
}
.mainLinkDropdown {
position: relative;
display: inline-block;
padding: 5px;
}
.dropdownContent {
display: none;
position: absolute;
min-height: 30px;
min-width: 130px;
text-align: left;
background-color: #f1f1f1;
z-index: 10;
}
.dropdownContent a {
display: block;
color: black;
padding: 12px 16px;
text-decoration: none;
}
.mainLinkDropdown:hover .dropdownContent{
display: block;
}
.dropdownContent a:hover{
background-color: #ddd;
}
<div class="mainCountainer">
<div class="mainCountainerHead">
<div class="mainCountainerHeadLogo">
<img src="https://i.ibb.co/cYzWJFM/logo-Copy.jpg" title="logo" />
</div>
<div class="mainCountainerHeadTitle">
<h4>Welcome aboard!</h4>
</div>
<div class="mainCountainerHeadMenu">
<div class="mainLink">
<button class="mainLinkButton">Main</button>
</div>
<div class="mainLinkDropdown">
<button class="mainLinkButton">Dropdown</button>
<div class="dropdownContent">
Link 1
Link 2
Link 3
</div>
</div>
<div class="mainLink">
<button class="mainLinkButton">Contacts</button>
</div>
</div>
</div>
</div>

Answer 1

In answer to your question:
That's because the float property puts the HTML elements out of the normal page flow, and this causes what you're experiencing. Its effect is similar to position: absolute which is to move the element to "a different layer".
How to solve it?
Well... there are a lot of ways to achieve what you want, and almost all of them requires to refactorize your code. Actually, you have a lot of code that makes it difficult to achieve your goal. You should get rid of float and start using other technics like Flexbox.
I could show you a solution if you provide a sketch of the layout you want.

Answer 2

change the CSS for img to this
.mainCountainerHeadLogo img {
width: 100%;
height: 100%;
margin: auto
}