下面是一个示例，通过设置延迟和持续时间来控制文本之间的间距

.marquee {
  background-color: #ddd;
  width: 500px;
  margin: 0 auto;
  overflow: hidden;
  white-space: nowrap;
}
.marquee span {
  display: inline-block;
  font-size: 20px;
  position: relative;
  left: 100%;
  animation: marquee 8s linear infinite;
}
.marquee:hover span {
  animation-play-state: paused;
}

.marquee span:nth-child(1) {
  animation-delay: 0s;
}
.marquee span:nth-child(2) {
  animation-delay: 0.8s;
}
.marquee span:nth-child(3) {
  animation-delay: 1.6s;
}
.marquee span:nth-child(4) {
  animation-delay: 2.4s;
}
.marquee span:nth-child(5) {
  animation-delay: 3.2s;
}

@keyframes marquee {
  0%   { left: 100%; }
  100% { left: -100%; }
}

<p class="marquee">
  <span>this is a</span>
  <span>simple marquee</span>
  <span>using css</span>
  <span>only tech</span>
  <span>with a delay</span>
</p>

如果选取框足够大，则可以在动画中期交换其中一个集合。
我认为这是您单独使用CSS所能达到的最大限度

.marquee {
  width: 100%;
  height: 80px;
  margin: 0 auto;
  overflow: hidden;
  white-space: nowrap;
  border: 1px solid blue;
}
.marquee-content {
  display: inline-block;
  margin-top: 5px;
  animation: marquee 15s linear infinite;
}
.item-collection-1 {
  position: relative;
  left: 0%;
  animation: swap 15s linear infinite;
}
@keyframes swap {
  0%, 50% {
    left: 0%;
  }
  50.01%,
  100% {
    left: 100%;
  }
}
.marquee-content:hover {
  animation-play-state: paused
}
.item1 {
  display: inline-block;
  height: 70px;
  width: 140px;
  background: cyan;
  vertical-align: top;
  margin-left: 15px;
}
.item2 {
  display: inline-block;
  height: 70px;
  width: 100px;
  background: magenta;
  vertical-align: top;
  margin-left: 15px;
  line-height: 14px;
}
/* Transition */

@keyframes marquee {
  0% {
    transform: translateX(0)
  }
  100% {
    transform: translateX(-100%)
  }
}

<div class="marquee">
<div class="marquee-content">
    <span class="item-collection-1">
        <span><img src="https://cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-icon@2.png" height="80"></span>
        <span class="item1"></span>
        <span><img src="https://cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-icon@2.png" height="80"></span>
        <span class="item1"></span>
        <span class="item1"></span>
        <span class="item1"></span>
        <span class="item1"></span>
    </span>
    <span class="item-collection-2">
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
        <span class="item2"></span>
    </span>
</div>
</div>