<li class="list__item">
    <div class="param">
      <span class="param__prop">Вязкость:</span><span class="param__value">30 ч</span>
      
    </div>
  </li>
.item_info ul > li {
    margin: 0px 0px 5px;
    list-style-type: none;
    position: relative;
    width: 100%;
    display: inline-flex;
}
.param {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    flex-wrap: nowrap;
    line-height: 1.4;
    width: 100%;
}
.param__prop {
   flex-grow: 1;
    position: relative;
    display: flex;
    overflow: hidden;
    align-items: baseline;
}
.param__prop:after {
     content: '';
    margin-left: 0.3em;
    bottom: 0.35em;
    width: 100%;
    border-bottom: 0.1em dotted;
}
.param__value {
    float: right;
    padding-left: 0.2em;
    display: block;
    text-align: right;
}
 li {
 
    list-style-type: none;
    position: relative;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.1/jquery.min.js