Rectangle 27 0

First issue
height:43px

And for second you have to set border-bottom:none like,

li{
    position:absolute;
    margin-left:0px;
    height:43px;
}
li.active{
    border-bottom:none;
}
<div class="tabbable" >
    <ul class="nav nav-tabs" ><!--tabs-->
          <li style="" id="logintab">
               <a href="#pane_login" data-toggle="tab" id="logintab_a">Login</a></li>
          <li class="active" id="reg_tab" >
              <a href="#pane_reg" data-toggle="tab" id="regtab_a">Registration</a></li>
    </ul>
    <div class="tab-content"><!--login tab content-->
        <div id="pane_login" class="tab-pane active">
        </div>
     </div>

     <div class="tab-content"><!--login tab content-->
        <div id="pane_register" class="tab-pane active">
        </div>
     </div>
</div><!--/Tabbable-->

jquery - How to set height and border of bootstrap tabs? - Stack Overf...

jquery html css twitter-bootstrap
Rectangle 27 0

I'm taking a demo of @Rohan Kumar.

Just changes of css: you need to do as the following

First Issue: you need to set border-bottom as the below contents background as if you are using full border

li.active {
    border-bottom:1px solid white;
}

Second Issue: you can do as @Rohan Kumar by defining the height or you can set margin and padding to 0 if needed increase the padding value for top and bottom.

jquery - How to set height and border of bootstrap tabs? - Stack Overf...

jquery html css twitter-bootstrap
Rectangle 27 0

Sharing my solution just in case someone else has to adjust the height:

.nav-tabs > li > a
{
    /* adjust padding for height*/
    padding-top: 4px; 
    padding-bottom: 4px;
}

The second issue could be resolved by adjusting margin of active anchor

.nav-tabs > li.active > a:focus, .nav-tabs > li.active > a
{
    margin-top: 1px;
}
.nav-tabs > li {
    margin-bottom: 0px; 
}
.nav-tabs > li.active {
    margin-bottom: -1px;    
}

jquery - How to set height and border of bootstrap tabs? - Stack Overf...

jquery html css twitter-bootstrap