style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "sans";
  background-color: #19172e;
  color: white;
  user-select: none;
}

@font-face {
  font-family: "sans";
  src: url(font/sans.ttf);
}

h2 {
  top: 0;
  padding-top: 20px;
  color: white;
  font-size: 2rem;
  text-align: center;
}

.container {
  max-width: 290px;
  margin: 50px auto 0;

}

#display {
  text-align: right;
  height: 60px;
  padding-right: 10px;
  line-height: 80px;
  font-size: 1.5rem;
  border-radius: 20px 20px 0 0;
  background-color: white;
  color: black;
  display: flex;
  flex-direction: column;
  justify-content: space-evenly;
  align-items: flex-end;
  overflow: hidden;
}

.buttons {
  display: grid;
  grid-template-columns: 0.8fr 0.8fr 0.8fr 0.8fr 0.8fr;
}

.button {
  border: 0.5px solid white;
  line-height: 60px;
  text-align: center;
  font-size: 1.7rem;
  cursor: pointer;
}

.button.left {
  border-radius: 0 0 0 15px;
}

.button.right {
  border-radius: 0 0 15px 0;
  size: 40px;
}

#equal {
  background-color: rgb(85, 85, 255);
}

#equal:active {
  background-color: #1e8e3e !important;
}

.button:active {
  background-color: #1e8e3e;
}

.footer {
  color: white;
  font-size: 1rem;
  left: 0;
  right: 0;
  bottom: 0;
  position: fixed;
  text-align: center;
}