I have some trouble with absolute position.
<div class="frame" style="position:relative; width:100px;height:100%; box-sizing:border-box; border:10px solid black;">
<div class="problem" style="width:20px; height:100%; position:absolute; right:-20px;"></div>
</div>
The problem is the ".problem" is using the right boundary of ".frame" without considering border width, so basically it is inside the frame a 20px; I wonder how can let the ".problem" use the boundary of border as right?