*{
    box-sizing: border-box;

}
body{
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: linear-gradient(180deg, #4f7cc8 0%, #2a4f8f 60%, #1e355f 100%)
}
.calculator{
    width: 400px;
    background: #ffffff;
    padding: 20px;
    border-radius: 18px;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.25);
}

.display{
    width: 100%;
    height: 70px;
    padding: 15px;
    margin-bottom: 20px;
    background: #f4f7fc;
    font-size: 32px;
    text-align: right;
    color: #2c3e50;
    overflow: hidden;
}

.button{
    display: grid;
    grid-template-columns: repeat(4,1fr);
    gap: 10px;
}

button{
    height: 56px;
    border: none;
    border-radius: 14px;
    background: #eef2f7;
    font-size: 18px;
    font-weight: 500;
    color: #2c3e50;
    cursor: pointer;
    transition: transform 0.05s ease, box-shadow 0.05s ease;
}
button:active {
  transform: scale(0.97);
  box-shadow: inset 0 3px 6px rgba(0, 0, 0, 0.15);
}
.equal {
  background: linear-gradient(180deg, #3b82f6, #2563eb);
  color: #ffffff;
}
.zero{
    grid-column: span 3;
}

button .operator{
  background: #dbe7ff;
  color: #1f4fd8;
}