<div class="room">
  <div class="target">
    <div class="target-title">Text here is very very long that it might get truncate if this box get resized too small</div>
    <div class="target-button">Button</div>
  </div>
</div>

body {
  width: 100vw;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.room {
  background: #eee;
  overflow: hidden;
  padding: 10px;
  border: 2px dashed #9e9e9e;
  resize: horizontal;
  cursor: pointer;
  height: 68px;
  width: 855px;
  display: flex;
  justify-content: space-between;
}

.target {
    display: flex;
    width: 100%;
    justify-content: space-between;
    align-items: center;
}

.target-title {
    overflow: hidden;
    padding: 5px;
    min-width: 0;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.target-button {
    padding: 5px 10px;
    background: #2196F3;
    color: white;
}