根據不同的內容以不同的方式處理溢出

html {
  box-sizing: border-box;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

body {
  margin: 64px auto;
  text-align: center;
  max-width: 640px;
  width: 94%;
  background-repeat: no-repeat;
  height: 100vh;
  background-color: #8bc6ec;
  background-image: linear-gradient(135deg, #8bc6ec 0%, #9599e2 100%);
}

.demo {
  background-color: white;
  padding: 2rem;
  border-radius: 0.5rem;
  max-height: 400px;
  overflow-y: scroll;
}

.demo,
.demo p {
  margin: 4em 0;
  text-align: center;
}

.button {
  background-color: #ea4c89;
  border-radius: 8px;
  border-style: none;
  box-sizing: border-box;
  color: #ffffff;
  cursor: pointer;
  display: inline-block;
  font-family: "Haas Grot Text R Web", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 14px;
  font-weight: 500;
  height: 40px;
  line-height: 20px;
  list-style: none;
  margin: 0;
  outline: none;
  padding: 10px 16px;
  position: relative;
  text-align: center;
  text-decoration: none;
  transition: color 100ms;
  vertical-align: baseline;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}

.button:hover,
.button:focus {
  background-color: #f082ac;
}


/**
 * Tooltip Styles
 */


/* Add this attribute to the element that needs a tooltip */

[data-tooltip] {
  position: relative;
  z-index: 2;
  cursor: pointer;
}


/* Hide the tooltip content by default */

[data-tooltip]:before,
[data-tooltip]:after {
  visibility: hidden;
  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=0)";
  filter: progid: DXImageTransform.Microsoft.Alpha(Opacity=0);
  display: none;
  pointer-events: none;
}


/* Position tooltip above the element */

[data-tooltip]:before {
  content: attr(data-tooltip);
  background-color: white;
  color: black;
  position: absolute;
  width: max-content;
  border: solid black 1.5px;
  padding: 5px 10px;
  border-radius: 10px;
  left: 102%;
  top: 115%;
}


/* Show tooltip content on hover */

[data-tooltip]:hover:before,
[data-tooltip]:hover:after {
  visibility: visible;
  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=100)";
  filter: progid: DXImageTransform.Microsoft.Alpha(Opacity=100);
  display: block;
}

<div class="demo">

  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It
    has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum. Why do we use it? It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum
    is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model
    text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like). Where does it come from? Contrary to
    popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the
    more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum"
    (The Extrem<button class="button" data-tooltip="I’m the tooltip text on the right of the button that extends out pretty far">I’m a button with a tooltip</button></p>
</div>