ตำแหน่งของฉัน: Sticky Element ไม่เหนียวเมื่อใช้ flexbox

.flexbox-wrapper {
  display: flex;
  height: 600px;
}
.regular {
  background-color: blue;
}
.sticky {
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  background-color: red;
}

<div class="flexbox-wrapper">
  <div class="regular">
    This is the regular box
  </div>
  <div class="sticky">
    This is the sticky box
  </div>
</div>

.flexbox-wrapper {
  display: flex;
  overflow: auto;
  height: 200px;          /* Not necessary -- for example only */
}
.regular {
  background-color: blue; /* Not necessary -- for example only */
  height: 600px;          /* Not necessary -- for example only */
}
.sticky {
  position: -webkit-sticky; /* for Safari */
  position: sticky;
  top: 0;
  align-self: flex-start; /* <-- this is the fix */
  background-color: red;  /* Not necessary -- for example only */
}

<div class="flexbox-wrapper">
  <div class="regular">
    This is the regular box
  </div>
  <div class="sticky">
    This is the sticky box
  </div>
</div>

body {
  height: 100vh;
  width: 100vw;
  display: flex;
  flex-direction: column;
}

body>header {
  background-color: red;
  color: white;
  padding: 1em;
}

.content {
  overflow-x: hidden;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

article {
  position: relative;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.horizontal_slide {
  display: flex;
  overflow-x: auto;
  background-color: lightblue;
  padding: .5em;
}

.horizontal_slide>* {
  width: 1000px;
}

.toolbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background-color: lightgray;
  padding: .5em;
  display: flex;
}

<header>Fancy header with height adjusting to variable content</header>
<div class="content">
  <article class="card">
    <h1>One of several cards that flips visibility</h1>
    <div class="overflow_x_wrapper">
      <div class="horizontal_slide">
        <div>Reason why `overflow-x: hidden` on the parent is required
        </div>
        <div>Reason why `overflow-x: hidden` on the parent is required
        </div>
        <div>Reason why `overflow-x: hidden` on the parent is required
        </div>
      </div>
      <div class="toolbar">Sticky toolbar part-way down the content</div>
      <p>Rest of vertically scrollable container with variable number of child containers and other elements</p>
      <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
        dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
  </article>
  </div>