cant find the reason why when i cant use the button when i make my web browser smaller?

i tried looking in the internet but u cant find a solution

```
<nav class="navbar navbar-inverse navbar-fixed-top">
            <div class="container-fluid">
                <div class="navbar-header">
                    <button class="navbar-toggler  navbar-toggler-right" type="button" aria-controls="#ex1" aria-expanded="false" aria-label="Toggle navigation" data-toggle="collapse" data-target="ex1">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="#">לוגו</a>
                </div>

                <div class="collapse navbar-collapse" id="ex1">
                    <ul class="nav navbar-nav navbar-right">
                        <li class="active"><a class="nav-link" href="#">דף הבית</a></li>
                        <li class="nav-item"><a class="nav-link" href="#">Link</a></li>
                        <li class="nav-item"><a class="nav-link" href="#">Link</a></li>
                        <li class="nav-item"><a class="nav-link" href="#">Link</a></li>
                        <li class="nav-item"><a class="nav-link" href="#">Link</a></li>
                    </ul>
                </div>
            </div>
        </nav>

```