position

position: static;

position: relative;
top: 40px;
left: 40px;

position: absolute;
inset-inline-start: 40px;
inset-block-start: 40px;

position: sticky;
top: 20px;

<section class="default-example" id="default-example">
  <div id="example-element-container">
    <p>
      In this demo you can control the <code>position</code> property for the
      yellow box.
    </p>
    <div class="box"></div>
    <div class="box" id="example-element"></div>
    <div class="box"></div>
    <p class="clear">
      To see the effect of <code>sticky</code> positioning, select the
      <code>position: sticky</code> option and scroll this container.
    </p>
    <p>
      The element will scroll along with its container, until it is at the top
      of the container (or reaches the offset specified in <code>top</code>),
      and will then stop scrolling, so it stays visible.
    </p>
    <p>
      The rest of this text is only supplied to make sure the container
      overflows, so as to enable you to scroll it and see the effect.
    </p>
    <hr />
    <p>
      Far out in the uncharted backwaters of the unfashionable end of the
      western spiral arm of the Galaxy lies a small unregarded yellow sun.
      Orbiting this at a distance of roughly ninety-two million miles is an
      utterly insignificant little blue green planet whose ape-descended life
      forms are so amazingly primitive that they still think digital watches are
      a pretty neat idea.
    </p>
  </div>
</section>

section {
  align-items: flex-start;
  overflow: auto;
}

.box {
  background-color: rgb(0 0 255 / 0.2);
  border: 3px solid blue;
  float: left;
  width: 65px;
  height: 65px;
}

.box + .box {
  margin-left: 10px;
}

.clear {
  clear: both;
  padding-top: 1em;
}

#example-element-container {
  position: relative;
  text-align: left;
}

#example-element {
  background-color: yellow;
  border: 3px solid red;
  z-index: 1;
}

position: static;
position: relative;
position: absolute;
position: fixed;
position: sticky;

/* Giá trị toàn cục */
position: inherit;
position: initial;
position: revert;
position: revert-layer;
position: unset;

<div class="box" id="one">One</div>
<div class="box" id="two">Two</div>
<div class="box" id="three">Three</div>
<div class="box" id="four">Four</div>

* {
  box-sizing: border-box;
}

.box {
  display: inline-block;
  width: 100px;
  height: 100px;
  background: red;
  color: white;
}

#two {
  position: relative;
  top: 20px;
  left: 20px;
  background: blue;
}

<h1>Absolute positioning</h1>

<p>
  I am a basic block level element. My adjacent block level elements sit on new
  lines below me.
</p>

<p class="positioned">
  By default we span 100% of the width of our parent element, and we are as tall
  as our child content. Our total width and height is our content + padding +
  border width/height.
</p>

<p>
  We are separated by our margins. Because of margin collapsing, we are
  separated by the width of one of our margins, not both.
</p>

<p>
  inline elements <span>like this one</span> and <span>this one</span> sit on
  the same line as one another, and adjacent text nodes, if there is space on
  the same line. Overflowing inline elements
  <span>wrap onto a new line if possible — like this one containing text</span>,
  or just go on to a new line if not, much like this image will do:
  <img src="https://mdn.github.io/shared-assets/images/examples/long.jpg" />
</p>

* {
  box-sizing: border-box;
}

body {
  width: 500px;
  margin: 0 auto;
}

p {
  background: aqua;
  border: 3px solid blue;
  padding: 10px;
  margin: 10px;
}

span {
  background: red;
  border: 1px solid black;
}

.positioned {
  position: absolute;
  background: yellow;
  inset-block-start: 30px;
  inset-inline-start: 30px;
}

<div class="outer">
  <p>
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam congue tortor
    eget pulvinar lobortis. Vestibulum ante ipsum primis in faucibus orci luctus
    et ultrices posuere cubilia Curae; Nam ac dolor augue. Pellentesque mi mi,
    laoreet et dolor sit amet, ultrices varius risus. Nam vitae iaculis elit.
    Aliquam mollis interdum libero. Sed sodales placerat egestas. Vestibulum ut
    arcu aliquam purus viverra dictum vel sit amet mi. Duis nisl mauris, aliquam
    sit amet luctus eget, dapibus in enim. Sed velit augue, pretium a sem
    aliquam, congue porttitor tortor. Sed tempor nisl a lorem consequat, id
    maximus erat aliquet. Sed sagittis porta libero sed condimentum. Aliquam
    finibus lectus nec ante congue rutrum. Curabitur quam quam, accumsan id
    ultrices ultrices, tempor et tellus.
  </p>
  <p>
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam congue tortor
    eget pulvinar lobortis. Vestibulum ante ipsum primis in faucibus orci luctus
    et ultrices posuere cubilia Curae; Nam ac dolor augue. Pellentesque mi mi,
    laoreet et dolor sit amet, ultrices varius risus. Nam vitae iaculis elit.
    Aliquam mollis interdum libero. Sed sodales placerat egestas. Vestibulum ut
    arcu aliquam purus viverra dictum vel sit amet mi. Duis nisl mauris, aliquam
    sit amet luctus eget, dapibus in enim. Sed velit augue, pretium a sem
    aliquam, congue porttitor tortor. Sed tempor nisl a lorem consequat, id
    maximus erat aliquet. Sed sagittis porta libero sed condimentum. Aliquam
    finibus lectus nec ante congue rutrum. Curabitur quam quam, accumsan id
    ultrices ultrices, tempor et tellus.
  </p>
  <div class="box" id="one">One</div>
</div>

* {
  box-sizing: border-box;
}

.box {
  width: 100px;
  height: 100px;
  background: red;
  color: white;
}

#one {
  position: fixed;
  top: 80px;
  left: 10px;
  background: blue;
}

.outer {
  width: 500px;
  height: 300px;
  overflow: scroll;
  padding-left: 150px;
}

#one {
  position: sticky;
  top: 10px;
}

<dl>
  <div>
    <dt>A</dt>
    <dd>Andrew W.K.</dd>
    <dd>Apparat</dd>
    <dd>Arcade Fire</dd>
    <dd>At The Drive-In</dd>
    <dd>Aziz Ansari</dd>
  </div>
  <div>
    <dt>C</dt>
    <dd>Chromeo</dd>
    <dd>Common</dd>
    <dd>Converge</dd>
    <dd>Crystal Castles</dd>
    <dd>Cursive</dd>
  </div>
  <div>
    <dt>E</dt>
    <dd>Explosions In The Sky</dd>
  </div>
  <div>
    <dt>T</dt>
    <dd>Ted Leo &amp; The Pharmacists</dd>
    <dd>T-Pain</dd>
    <dd>Thrice</dd>
    <dd>TV On The Radio</dd>
    <dd>Two Gallants</dd>
  </div>
</dl>

* {
  box-sizing: border-box;
}

dl > div {
  background: white;
  padding-top: 24px;
}

dt {
  background: #b8c1c8;
  border-bottom: 1px solid #989ea4;
  border-top: 1px solid #717d85;
  color: white;
  font:
    bold 18px/21px "Helvetica",
    "Arial",
    sans-serif;
  margin: 0;
  padding: 2px 0 0 12px;
  position: -webkit-sticky;
  position: sticky;
  top: -1px;
}

dd {
  font:
    bold 20px/45px "Helvetica",
    "Arial",
    sans-serif;
  margin: 0;
  padding-left: 12px;
  white-space: nowrap;
}

dd + dd {
  border-top: 1px solid #cccccc;
}

Use scrollbars to put the light bulbs(💡) in the right place in the following
text:
<div>
  <p>
    The representation of an idea by a light bulb(<span class="bulb">💡</span>)
    is a commonly used metaphor that symbolizes the moment of inspiration or the
    birth of a new idea. The association between a light bulb and an idea can be
    traced back to the invention of the incandescent light bulb(<span
      class="bulb"
      >💡</span
    >) by Thomas Edison in the late 19th century. The light bulb is a powerful
    symbol because it represents illumination, clarity, and the sudden
    brightening of one's thoughts or understanding. When someone has an idea, it
    is often described as a light bulb turning on in their mind, signifying a
    moment of insight or creativity. The image of a light bulb also suggests the
    idea of energy, power, and the potential for growth and development.
  </p>
</div>

div {
  width: 400px;
  height: 200px;
  overflow: scroll;
  scrollbar-width: thin;
  font-size: 16px;
  font-family: "Verdana";
  border: 1px solid;
}

p {
  width: 600px;
  user-select: none;
  margin: 0;
  border: 110px solid transparent;
}

.bulb {
  position: sticky;
  inset: 50px 100px;
}

div {
  /* mark area defined by the inset boundaries using gray color */
  background: linear-gradient(#99999999, #99999999) 100px 50px / 192px 100px
    no-repeat;
}