* {
  box-sizing: border-box;
  color:#fff;
}
body {
  margin: 0;
  background: linear-gradient(#1d1f27,#282c34);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
.calculator {
  background: #112240;
  padding: 20px;
  border-radius: 20px;
  box-shadow: 0 0 18px #00ffff33
  
}
.screen {
  width: 100%;
  height: 60px;
  border-radius: 10px;
  background: #3a3f4b;
  color: #0ff;
  font-size: 2em;
  text-align: right;
  padding: 10px;
  margin-bottom: 20px;
  overflow-x: auto;
}
.buttons {
  display: grid;
  grid-template-columns: repeat(4, 70px);
  gap: 15px;
  justify-content: center;
}
button {
  width: 70px;
  height: 70px;
  font-size: 1.5em;
  background: #1E2B45;
  border: none;
  border-radius: 15px;
  cursor: pointer;
  box-shadow: 0 0 10px #00ffff66;
  transition: all 0.2s;
}
button:hover {
  background: #00f5d4;
  color: #000;
  box-shadow: 0 0 10px #0ff;
}
.operator {
  color: #ff9f1c;
}
.equal {
  background:  green;
  color: #000;box-shadow: 0 0 7px #0ff;
  
}
.delete{
  background: #e63946;
box-shadow: 0 0 7px #0ff;
}
@media (max-width: 400px) {
  .buttons {
    grid-template-columns: repeat(4, 60px);
    gap: 10px;
  }
  button {
    width: 60px;
    height: 60px;
    font-size: 1.3em;
  }
}