Answer 2

HTML

<div class="container-1">

  <div class="grid">
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
    <div class="grid-unit"></div>
  </div>
  <div class="container-2">
    <div class="box box-1"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
  </div>
</div>

CSS

html {
  font-size: 36px;
}

body {
  margin: 0;
}

.container-1 {
  position: absolute;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -ms-flex-pack: center;
  justify-content: center;
  width: 100%;
  height: 100%;
}

.grid {
  position: absolute;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
  width: 100%;
  height: 100%;
}

.grid-unit {
  width: 8rem;
  height: 1rem;
  border-right: 1px solid #000;
  border-bottom: 1px solid #000;
  border-left: 1px solid #000;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.container-2 {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
}

.box {
  height: 1rem;
  width: 1rem;
  margin-bottom: 1rem;
  background-color: blue;
}

JavaScript

function snapFunction() {
  var box = document.querySelector('.box-1');
  var rect = box.getBoundingClientRect();
  var bottomOrig = rect.bottom;

  var htmlRoot = document.querySelector('html');
  var style = getComputedStyle(htmlRoot);
  var remValue = parseInt(style.getPropertyValue('font-size'), 10);

  var bottomNew = Math.floor(bottomOrig / remValue) * remValue;
  var fix = bottomOrig - bottomNew;
  
  

        console.log("bottomOrig: " + bottomOrig )
        console.log("remValue: " + remValue)
        console.log("bottomNew: " + bottomNew )

  $('.container-2').css("margin-bottom", fix + "px");
  console.log( $('.container-2'))
  console.log( "fix + 'px'")
  console.log( $('.container-2').css("margin-bottom"))
}

(function() {

  snapFunction();

})();

$( window ).resize(function() {
  snapFunction();
});