<!DOCTYPE html>
<style>
   .inner-box {
       width: 100px;
       height: 100px;
       background-color: green;
       position: relative;
   }
   .position-left-100 {
       left: 100px;
   }
   .position-top-100 {
       top: 100px;
   }
   .container-box {
       width: 200px;
       height: 200px;
   }
</style>
<div class="container-box">
    <div class="inner-box position-top-100"></div>
</div>
<div class="container-box">
    <div class="inner-box position-left-100"></div>
</div>