style.css

*,
::before,
::after {
  margin: 0;
  padding: 0;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}
main {
  display: grid;
  align-items: center;
  justify-content: center;
  text-align: center;
  background-color: beige;
  width: 400px;
  padding: 140px 0;
  border-radius: 16px;
}
main p {
  font-size: 25px;
  background-color: #ffffff;
  border-radius: 10px;
  padding: 5px 0;
  margin-bottom: 30px;
  margin-top: -50px;
  z-index: 1;
  visibility: hidden;
}
.show {
  visibility: visible;
}
main h1 {
  font-size: 75px;
  margin: 15px 0;
}
main button {
  padding: 5px 8px;
  font-size: 20px;
  border-radius: 7px;
  margin: 15px 2px;
  box-shadow: none;
  outline: none;
  border: 1px solid #f1f1f1;
  color: #ffffff;
  transition: 0.3s;
}
main button:hover {
  opacity: 0.7;
}
.increase {
  background-color: green;
}
.reset {
  background-color: red;
}
.decrease {
  background-color: blue;
}