how to fix two column with the same height have different size

Question

I have a row with three columns that have a size of 10% 80% 10% respectively, but when I view the page the player column is larger than the slider column. I don't understand why because the column player and slider have the same size but are rendered different. when I open the inspection I see that the sum of the values ​​of the heights of the single 3 columns exceeds the height of the body of the document.

html {
    height: 100%;
}

body {
    height: 100%;
    overflow-y:hidden;
}

body {
    font-family: 'Muli', sans-serif;
}

.navbar-brand {
    height:10%;
}

.container-fluid {
    height: 100%;
    padding-left: 0px;
    padding-right: 0px;
    overflow: hidden;
}

.row {
    margin-left: 0px;
    margin-right: 0px;
    overflow: hidden;
}

.row-first {
    height:70%;
    overflow: hidden;
}

.row-full-height {
    height:100%;
    overflow: hidden;
}

.full-width
{
    width:100%;
    overflow: hidden;
}

.height20p{
    height:20%;
    overflow: hidden;
}

.row-second {
    height:30%;
    overflow: hidden;
}

<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">

<nav class="navbar navbar-expand-lg navbar-dark bg-primary">
        <a class="navbar-brand" href="#">JS</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>


        <div class="navbar-collapse collapse w-100 justify-content-center" id="navbarSupportedContent">
            <ul class="navbar-nav mx-auto">
                <li class="nav-item">
                    <a class="nav-link" href="#">Home</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Contact</a>
                </li>
            </ul>
        </div>  
    </nav>


    <div class="container-fluid">
        <div class="row no-gutters" style="height:100%" >
            <div class="col-sm-2" style="background-color: rgb(105, 128, 0)"> 1 </div>
            <div class="col-sm-7" style="background-color: rgb(240, 144, 1)">  <!-- contiene player 3d, slider ---> 
                <div class="row no-gutters" style="height:100%" >
                    <div class="col-sm-12" style="background-color: rgb(128, 0, 21); height:10%"> player </div>
                    <div class="col-sm-12" style="background-color: rgb(78, 59, 82); height:80%"> 3d </div>
                    <div class="col-sm-12" style="background-color: rgb(115, 139, 117); height:10%"> slider  </div>
                </div>
            </div>
            <div class="col-sm-3" style="background-color: rgb(230, 64, 14)"> 4 </div>
      </div>
    </div>

Answer 1

That is because your container-fluid has height:100%, making it gets the page's height. To fix that you have to discount the navbar height in the container-fluid's height.

height: calc(100% - 56px);

html {
    height: 100%;
}

body {
    height: 100%;
    overflow-y:hidden;
}

body {
    font-family: 'Muli', sans-serif;
}

.navbar-brand {
    height:10%;
}

.container-fluid {
    height: calc(100% - 56px);
    padding-left: 0px;
    padding-right: 0px;
    overflow: hidden;
}

.row {
    margin-left: 0px;
    margin-right: 0px;
    overflow: hidden;
}

.row-first {
    height:70%;
    overflow: hidden;
}

.row-full-height {
    height:100%;
    overflow: hidden;
}

.full-width
{
    width:100%;
    overflow: hidden;
}

.height20p{
    height:20%;
    overflow: hidden;
}

.row-second {
    height:30%;
    overflow: hidden;
}

<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">

<nav class="navbar navbar-expand-lg navbar-dark bg-primary">
        <a class="navbar-brand" href="#">JS</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>


        <div class="navbar-collapse collapse w-100 justify-content-center" id="navbarSupportedContent">
            <ul class="navbar-nav mx-auto">
                <li class="nav-item">
                    <a class="nav-link" href="#">Home</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Contact</a>
                </li>
            </ul>
        </div>  
    </nav>


    <div class="container-fluid">
        <div class="row no-gutters" style="height:100%" >
            <div class="col-sm-2" style="background-color: rgb(105, 128, 0)"> 1 </div>
            <div class="col-sm-7" style="background-color: rgb(240, 144, 1)">  <!-- contiene player 3d, slider ---> 
                <div class="row no-gutters" style="height:100%" >
                    <div class="col-sm-12" style="background-color: rgb(128, 0, 21); height:10%"> player </div>
                    <div class="col-sm-12" style="background-color: rgb(78, 59, 82); height:80%"> 3d </div>
                    <div class="col-sm-12" style="background-color: rgb(115, 139, 117); height:10%"> slider  </div>
                </div>
            </div>
            <div class="col-sm-3" style="background-color: rgb(230, 64, 14)"> 4 </div>
      </div>
    </div>