Stop page jump to an anchor tag (without javascript?)

HTML

<div id="fixed-area">
    <ul id="tab">
        <li><a href="#tab1">Tab 1</a></li>
        <li><a href="#tab2">Tab 2</a></li>
        <li><a href="#tab3">Tab 3</a></li>
        <li><a href="#tab4">Tab 4</a></li>
    </ul>
    <div id="body-tab">
        <div class="box" id="tab1">
            <h2>Tab 1</h2>
        </div>
        <div class="box" id="tab2">
            <h2>Tab 2</h2>
        </div>
        <div class="box" id="tab3">
            <h2>Tab 3</h2>
        </div>
        <div class="box" id="tab4">
            <h2>Tab 4</h2>
        </div>
    </div>
    <button  class="btn" onclick="window.location.href=https://www.google.co.in">Tab 11
</div>

CSS

body {height:1000px;}

#fixed-area {
 position:fixed;
 top:30px;
 left:5%;   
}

ul#tab {
 width:350px;
 overflow:hidden;   
}

ul#tab li {
 display:inline;
 float:left;
 margin:0px 2px 2px 0px;   
}

ul#tab li a {
 background-color:black;
 color:white;
 padding:5px 10px;
 font:bold 11px Verdana,Arial,Sans-Serif;
 text-decoration:none;
 display:block; 
}

#body-tab {position:relative;width:350px;}

#body-tab .box {
 position:absolute;
 top:0px;
 left:0px;
 width:90%;
 height:200px;
 padding:5%;
 background-color:skyblue;
 font:bold 14px Georgia,Serif;
 color:black;
 opacity:0;
 height:0px;
 visibility:hidden;
 -webkit-transition:all 0.26s ease-out;   
 -moz-transition:all 0.26s ease-out;   
 -ms-transition:all 0.26s ease-out;   
 -o-transition:all 0.26s ease-out;   
 transition:all 0.26s ease-out;   
}

#body-tab .box:target {
 visibility:visible;
 height:200px;
 opacity:1;   
}

JavaScript

// Stop the page jump to an anchor tag (without javascript?)