*{
    box-sizing:border-box;
}

body{
    margin:0;
    font-family:Arial, sans-serif;
    background:linear-gradient(135deg,#1e3c72,#2a5298);
    display:flex;
    justify-content:center;
    align-items:center;
    height:100vh;
    overflow:hidden; /* Remove scroll */
}

.wrapper{
    width:100%;
    max-width:420px;
    padding:15px;
}

.calculator{
    background:#0f0f0f;
    padding:25px;
    border-radius:25px;
    box-shadow:0 20px 60px rgba(0,0,0,0.5);
}

h2{
    color:#fff;
    text-align:center;
    margin-bottom:20px;
}

.display{
    width:100%;
    height:50px;
    margin-bottom:12px;
    font-size:16px;
    padding:12px;
    border:none;
    border-radius:12px;
    background:#eaeaea;
    outline:none;
}

.display:focus{
    background:#fff;
}

.buttons{
    display:flex;
    justify-content:space-between;
    margin-top:10px;
}

.buttons button{
    width:48%;
    height:48px;
    font-size:15px;
    border:none;
    border-radius:12px;
    cursor:pointer;
}

.btn-clear{
    background:#e53935;
    color:#fff;
}

.btn-submit{
    background:#4caf50;
    color:#fff;
}

.result{
    background:#1c1c1c;
    color:#fff;
    padding:18px;
    border-radius:15px;
    margin-top:20px;
    font-size:14px;
    line-height:1.7;
}

@media(max-width:480px){
    body{
        padding:10px;
    }
}