<div class="splitter-left ">
    <div class="close-left-btn">
        <button class="btn btn-primary" id="toggle-menu">Click me</button>
    </div>
    <div class="container-fluid content-close">
        <div class="row">
            <div class="col-4">
                <p>Home</p>
            </div>
            <div class="col-4">
                <p>About</p>
            </div>
            <div class="col-4">
                <p>Contact</p>
            </div>
        </div>
</div>
</div>


<div class="splitter-right">
    <div class="container-fluid">
        <div class="row">
            <div class="col-12">
                <strong>Header options</strong>
              </div>
        </div>
</div>
</div>

.splitter-left {
            display: inline-block;
            width: 25%;
            max-width: 300px;
            min-width: 250px;
            background-color: #fff;
            margin-top: 10px;
            margin-left: -35px;
            vertical-align: top;
        }

  .splitter-right {
                display: inline-block;
                width: 85%;
                margin-top: 10px;
                position: relative;
                left: 50px;
                min-height: 400px;
            }

$("#toggle-menu").click(function () {
   if ($(".content-close").toggle()) {
   $(".splitter-left").toggleClass('sidemenu-close')
   $(".splitter-right").css({ width: '100%' });
    else {
   $(".splitter-right").css({ width: '75%' });
         }
   });

.sidemenu-close {
            width: 0% !important;
            min-width: 0% !important;
        }