.tab {
  overflow: hidden;
  border: 1px solid #ccc;
  background-color: #f1f1f1;
  display: flex;
  flex-wrap: nowrap;
  width: fit-content;
  margin: auto;
}

.tab button {
  background-color: inherit;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  transition: 0.3s;
  flex-shrink: 0;
}

body {
  background-color: black;
  color: white;
}

.tabcontent {
  /* This is crucial for initial hiding */
  display: none;
  margin: auto;
  width: 50%;
  padding: 10px;
  border: 2px solid green;
}