style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background: url(background.svg) center center/cover;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.mainContainar {
  width: 319px;
  height: 499px;
  backdrop-filter: blur(3px);
  background-color: rgba(238, 238, 238, 0.377);
  border: 2px solid rgb(116, 116, 116);
  user-select: none;
}
.mainContainar h1 {
  margin: 7px 0 0 7px;
  color: #d2dbe7;
}
.screen {
  width: 100%;
  height: 141px;
  padding: 8px;
  margin: 14px 0;
  background-color: rgba(238, 238, 238, 0.657);
}
#historyScreen {
  width: 100%;
  height: 60px;
  padding: 15px 0;
  text-align: end;
  font-size: 20px;
  background-color: #bcc0c300;
  border: none;
  overflow: hidden;
  outline: none;
}
#mainScreen {
    width: 100%;
  outline: none;
  text-align: end;
  font-size: 40px;
  height: 50px;
  background-color: #bcc0c300;
  border: none;
  overflow: hidden;
}
.buttns {
  display: grid;

  grid-template-columns: repeat(4, 1fr);
}
.btn {
  width: 76px;
  height: 53px;
  font-size: 30px;
  margin: 1px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(238, 238, 238, 0.657);
}
.btn:hover {
  background-color: rgba(238, 238, 238, 0.863);
  cursor: pointer;
}
.btn:active {
  background-color: #3c87fa;
  color: #eee;
}

#percentage:hover:before{
  content: attr(tooltip);
  font-size: 16px;
  background-color: #000;
  color: #fff;
  padding: 5px;
  width: 190px;
  clip-path: polygon(75% 0%, 100% 50%, 75% 100%, 0% 100%, 0 51%, 0% 0%);
  position: absolute;
  left: -200px;
}