Сохранение элементов списка в одной «строке»

.mainMenu {
  width: 100%;
  position: absolute;
  top: 90px;
  z-index: 100;
  display: flex
}

.mainMenu .tripleDot {
  float: left;
  width: 90px;
  font-family: Georgia, serif;
  font-size: 40px;
  font-style: italic;
  font-weight: bold;
  margin: 5px;
  line-height: 40px;
  text-align: center;
}

.mainMenu .tripleDot::after {
  position: relative;
  content: "";
  display: inline-block;
  width: 0.3em;
  height: 0.3em;
  border-right: 0.15em solid black;
  border-top: 0.15em solid black;
  transform: rotate(45deg);
  top: 5.3px;
}

.mainMenu .step {
  float: left;
  min-width: 100px;
  max-width: 200px;
  width: 25%;
}

.mainMenu .step-text {
  font-family: Georgia, serif;
  font-size: 18px;
  font-style: italic;
  font-weight: bold;
  text-align: center;
}

.mainMenu .step-number {
  font-family: Georgia, serif;
  font-size: 40px;
  font-style: italic;
  font-weight: bold;
  border-radius: 50%;
  width: 70px;
  height: 70px;
  line-height: 60px;
  text-align: center;
  margin: auto;
}

<ul class = "mainMenu">
  <li class = "step" id = "step1">
    <a href = "#">
      <div class = "step-number">A</div>
      <div class = "step-text">Select</div>
    </a>
  </li>
  <li class = "tripleDot xs-hidden">.....</li>
  <li class = "step" id = "step2">
    <a href = "#">
      <div class = "step-number">B</div>
      <div class = "step-text">Select</div>
    </a>
  </li>
  <li class = "tripleDot xs-hidden">.....</li>
  <li class = "step">

    <a href = "#">
      <div class = "step-number">C</div>
      <div class = "step-text">Upload</div>
    </a>
  </li>
</ul>