JSFiddle - React, Tailwind, and code Playground

HTML

<section>
<div class="letter-box clearfix"><span class="huge-letter">A</span><div class="cl-list"><div class="kunde"><span class="kundename"><a href="agentur/kunden/?activeclient=2">AAAAA</a></span></div></div></div>
<div class="letter-box clearfix"><span class="huge-letter">A</span><div class="cl-list"><div class="kunde"><span class="kundename"><a href="agentur/kunden/?activeclient=2">AAAAA</a></span></div></div></div>
<div class="letter-box clearfix"><span class="huge-letter">A</span><div class="cl-list"><div class="kunde"><span class="kundename"><a href="agentur/kunden/?activeclient=2">AAAAA</a></span></div></div></div>
<div class="letter-box clearfix"><span class="huge-letter">A</span><div class="cl-list"><div class="kunde"><span class="kundename"><a href="agentur/kunden/?activeclient=2">AAAAA</a></span></div></div></div>
<div class="letter-box clearfix"><span class="huge-letter">A</span><div class="cl-list"><div class="kunde"><span class="kundename"><a href="agentur/kunden/?activeclient=2">AAAAA</a></span></div></div></div>
</section>

CSS

@import url(http://fonts.googleapis.com/css?family=Open+Sans:400,600,700);

.clearfix:before,.clearfix:after { content: ""; display: table; }
.clearfix:after { clear: both; }
.clearfix { zoom: 1; }

section{
    
    border-top: 1px solid red;
    
    -webkit-column-count: 3;
    -webkit-column-gap: 20px;
    -moz-column-count: 3;
    -moz-column-gap: 20px;
    column-count: 3;
    column-gap: 20px;
    
    font-family: 'Open Sans', Courier;
}
.letter-box {
    -webkit-column-break-inside: avoid;
    -moz-column-break-inside: avoid;
    -o-column-break-inside: avoid;
    -ms-column-break-inside: avoid;
    column-break-inside: avoid;
    margin-bottom: 30px;
}
.huge-letter {
  border-top: 1px solid blue;
  font-family: 'Open Sans', courier;
  font-weight: 600;
  display: block;
  font-size: 2em;
  line-height: 56px;
  float: left;
  width: 70px;
  text-align: center;
}
.cl-list {
  display: block;
  float: right;
  width: 115px;
  font-family: 'Open Sans', courier;
  font-weight: 600;
  font-size: 13px;
  color: #A3A3A3;
  margin-top: 3px;
}
.kundename {
  margin-bottom: 3px;
  display: block;
}