CSS中的元素被描述为“在流中”或“脱离流”。流中的元素被赋予空间，并且空间被流中的其他元素所影响。如果通过浮动或定位元素使元素脱离流，则该元素的空间将不再受到其他流元素的影响。

对于绝对定位的元素，是最明显的。如果你设置一个元素 position: absolute ，该元素会从流中脱离，你需要确保这个元素不会与流中的元素重叠，且不影响你布局的其他部分的可读性。

<div class="container">
  <p>Veggies es bonus vobis, proinde vos postulo essum magis kohlrabi welsh onion daikon amaranth tatsoi tomatillo melon azuki bean garlic.</p><p>Gumbo beet greens corn soko endive gumbo gourd. Parsley shallot courgette tatsoi pea sprouts fava bean collard greens dandelion okra wakame tomato. Dandelion cucumber earthnut pea peanut soko zucchini.</p><p>Turnip greens yarrow ricebean rutabaga endive cauliflower sea lettuce kohlrabi amaranth water spinach avocado daikon napa cabbage asparagus winter purslane kale. Celery potato scallion desert raisin horseradish spinach carrot soko. Lotus root water spinach fennel kombu maize bamboo shoot green bean swiss chard seakale pumpkin onion chickpea gram corn pea. Brussels sprout coriander water chestnut gourd swiss chard wakame kohlrabi beetroot carrot watercress. Corn amaranth salsify bunya nuts nori azuki bean chickweed potato bell pepper artichoke.</p><p>Nori grape silver beet broccoli kombu beet greens fava bean potato quandong celery. Bunya nuts black-eyed pea prairie turnip leek lentil turnip greens parsnip. Sea lettuce lettuce water chestnut eggplant winter purslane fennel azuki bean earthnut pea sierra leone bologi leek soko chicory celtuce parsley jícama salsify.</p>
  <div class="item">

body {
  padding: 20px;
  font: 1em Helvetica Neue, Helvetica, Arial, sans-serif;}* {box-sizing: border-box;}
p {
  margin: 0 0 1em 0;}.container {
  border: 5px solid rgb(111,41,97);
  border-radius: .5em;
  padding: 10px;
  column-count: 2;
  max-width: 400px;
  position: relative;}.item {
  border-radius:.5em;
  position: absolute;
  top: 10px;
  left: 20px;
  background-color: rgba(111,41,97,.9);
  color: #fff;
  padding: 20px;
  width: 200px;}

然而，浮动元素也会从流中脱离，但后面的元素的文本将环绕该浮动元素。你可以设置后面元素的背景颜色，你会看到他们会上升并占用了原来浮动元素原来的空间。

<div class="container">
  <div class="item">
    I am floated and out of flow.
  </div>
  <p>Veggies es bonus vobis, proinde vos postulo essum magis kohlrabi welsh onion daikon amaranth tatsoi tomatillo melon azuki bean garlic.</p><p>Gumbo beet greens corn soko endive gumbo gourd. Parsley shallot courgette tatsoi pea sprouts fava bean collard greens dandelion okra wakame tomato. Dandelion cucumber earthnut pea peanut soko zucchini.</p><p>Turnip greens yarrow ricebean rutabaga endive cauliflower sea lettuce kohlrabi amaranth water spinach avocado daikon napa cabbage asparagus winter purslane kale. Celery potato scallion desert raisin horseradish spinach carrot soko. Lotus root water spinach fennel kombu maize bamboo shoot green bean swiss chard seakale pumpkin onion chickpea gram corn pea. Brussels sprout coriander water chestnut gourd swiss chard wakame kohlrabi beetroot carrot watercress. Corn amaranth salsify bunya nuts nori azuki bean chickweed potato bell pepper artichoke.</p><p>Nori grape silver beet broccoli kombu beet greens fava bean potato quandong celery. Bunya nuts black-eyed pea prairie turnip leek lentil turnip greens parsnip. Sea lettuce lettuce water chestnut eggplant winter purslane fennel azuki bean earthnut pea sierra leone bologi leek soko chicory celtuce parsley jícama salsify.</p></div>

body {
  padding: 20px;
  font: 1em Helvetica Neue, Helvetica, Arial, sans-serif;}* {box-sizing: border-box;}
p {
  margin: 0 0 1em 0;}.container {
  border: 5px solid rgb(111,41,97);
  border-radius: .5em;
  padding: 10px;
  max-width: 500px;}.item {
  border-radius:.5em;
  float: left;
  background-color: rgba(111,41,97,.9);
  color: #fff;
  padding: 20px;
  width: 100px;
  margin: 10px;}.container p:nth-of-type(1) {
  background-color: yellow;}

你可以在MDN上阅读更多有关 流中和脱离流 的信息。需要记住的重要一点是，如果从流中取出一个元素，则需要自己管理重叠，因为块流布局的常规规则不再适用。

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