*{
    margin:0;
    padding: 0;
    box-sizing: border-box;
    
}
body{
    height:100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background:radial-gradient(circle, #1f1f1f, #0a0a0a);
    font-family: 'Segoe UI', sans-serif;
}

.calculator{
    background: #111;
    padding: 30px;
    border-radius: 20px;
    box-shadow: 0 0 30px rgba(0, 255, 255, 0.2);
    width: 360px;
    border: 1px solid #00ffe0;
    animation: glowBox 2s infinite alternate;
}

@keyframes glowBox {
    from{
        box-shadow: 0 0 30px rgba(0, 255, 255, 0.4);
    }
    to{
      box-shadow: 0 0 60px rgba(0, 255, 255, 0.8);
   
    }
}

#input{
    width: 100%;
    height: 70px;
    background: #000;
    color: #00ff99;
    font-size: 30px;
    text-align: right;
    padding: 15px;
    border: none;
    border-radius: 12px;
    margin-bottom: 25px;
    box-shadow: inset 0 0 10px #00ffcc;
    outline: none;
}

.buttons{
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
}

button{
    padding: 18px;
    font-size: 22px;
    font-weight: bold;
    border: none;
    border-radius: 15px;
    cursor: pointer;
    background: #1a1a1a; 
    color: #00ffe0;
    box-shadow: 0 5px #000, 0 0 10px rgba(0, 255, 255, 0.3);
    transition: all 0.2s ease-in-out;

}

button:hover{
    background: #222;
    color: #fff;
    transform: translateY(-3px);
    box-shadow: inset 0 0 8px #00fff7, inset 0 0 5px #00fff7;
}

button:active{
    transform: translateY(2px);
    box-shadow: inset 0 0 8px #00ffcc;
}

button:nth-child(1) {
    background: #ff4d4d;
    color: white;
    box-shadow: 0 5px #000, 0 0 10px rgba( 255, 77, 77, 0.4);
}

button:nth-child(1):hover{
    background: #e60000;
    box-shadow: 0 0 15px #ff4d4d, inset 0 0 5px #ff4d4d;


}
button:nth-child(16) {
    background: #2ecc71;
    color: white;
    box-shadow: 0 5px #000, 0 0 10px rgba( 46, 204, 113, 0.4);
}

button:nth-child(16):hover{
    background: #27ae60;
    box-shadow: 0 0 15px #2ecc71, inset 0 0 5px #2ecc71;


}