设置最小值 最大值函数 | minmax

/* <inflexible-breadth>, <track-breadth> values */
minmax(200px, 1fr)
minmax(400px, 50%)
minmax(30%, 300px)
minmax(100px, max-content)
minmax(min-content, 400px)
minmax(max-content, auto)
minmax(auto, 300px)
minmax(min-content, auto)

/* <fixed-breadth>, <track-breadth> values */
minmax(200px, 1fr)
minmax(30%, 300px)
minmax(400px, 50%)
minmax(50%, min-content)
minmax(300px, max-content)
minmax(200px, auto)

/* <inflexible-breadth>, <fixed-breadth> values */
minmax(400px, 50%)
minmax(30%, 300px)
minmax(min-content, 200px)
minmax(max-content, 200px)
minmax(auto, 300px)

minmax( [ <length> | <percentage> | <flex> | min-content | max-content | auto ] , [ <length> | <percentage> | <flex> | min-content | max-content | auto ] )

#container {
  display: grid;
  grid-template-columns: minmax(max-content, 300px) minmax(200px, 1fr) 150px;
  grid-gap: 5px;
  box-sizing: border-box;
  height: 200px;
  width: 100%;
  background-color: #8cffa0;
  padding: 10px;
}

#container > div {
  background-color: #8ca0ff;
  padding: 5px;
}

<div id="container">
  <div>
    Item as wide as the content,<br/>
    but at most 300 pixels.
  </div>
  <div>
    Item with flexible width but a minimum of 200 pixels.
  </div>
  <div>
    Inflexible item of 150 pixels width.
  </div>
</div>