সিএসএস flex

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.container {
  display: flex;
  width: 300px;
  gap: 5px;
}

.item {
  background-color: coral;
  padding: 20px;
}

.grow {
  flex: 1;
}

.fixed {
  flex: 0 0 80px;
}
</style>
</head>
<body>

<div class="container">
  <div class="item grow"></div>
  <div class="item fixed"></div>
  <div class="item grow"></div>
</div>

</body>
</html>