I would use white-space: nowrap along with display: inline-block. Live demo (click).

By the way, try to use CSS instead of inline styles in your HTML. Inline styles should be avoided unless absolutely necessary.

<div class="row">
  <div></div>
  <div></div>
  <div></div>
  <div></div>

CSS:

.row {
  white-space: nowrap;
}

.row > div {
  width: 300px;
  display: inline-block;
}