body{
    height: 100vh;
    align-items: center;
    display: flex;
    flex-direction: column; 
    background: linear-gradient(135deg, #483d40, #a24b6e); 
    font-family: 'Poppins', sans-serif;
}

.calculator{
   border: 2px solid rgb(44, 44, 44);
   width: 100%;
   max-width: 350px;  
   margin: 0 auto;
   border-radius: 10px;
   box-shadow: 0px 4px 10px rgba(0,0,0,0.3);
   background: rgba(255, 255, 255, 0.1); 
}

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

.btn {
  border-radius: 25px !important;
  
  border: 1px solid rgb(43, 43, 43);
  box-shadow: 0px 4px 10px rgba(0,0,0,0.3);
}