@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@500&display=swap');

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

body{
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, #1f1c2c, #928dab);
    padding: 10px; /* for spacing on small screens */
}


.calculator{
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 20px;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(12px);
    box-shadow: 0px 8px 25px rgba(0, 0, 0, 0.3);
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 360px; /* fits mobile screens */
}


.calc-title{
    text-align: center;
    color: #fff;
    margin-bottom: 15px;
    font-size: 26px;
    letter-spacing: 1px;
}


input{
    width: 100%;
    border: none;
    padding: 20px;
    margin: 10px 0 20px 0;
    background: rgba(255, 255, 255, 0.05);
    box-shadow: inset 0px 4px 10px rgba(0, 0, 0, 0.3);
    border-radius: 12px;
    font-size: 32px;
    text-align: right;
    color: #fff;
    outline: none;
    word-wrap: break-word;
}

.calculator > div{
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin-bottom: 10px;
    width: 100%;
}


button{
    border: none;
    height: 60px;
    border-radius: 12px;
    background: linear-gradient(145deg, #2e2e2e, #202020);
    color: #ffffff;
    font-size: 18px;
    font-weight: 500;
    box-shadow: 3px 3px 8px rgba(0,0,0,0.5), -3px -3px 8px rgba(255,255,255,0.1);
    transition: all 0.2s ease-in-out;
    cursor: pointer;
    width: 100%;
}

button:hover{
    transform: scale(1.05);
    background: linear-gradient(145deg, #3a3a3a, #1c1c1c);
}


.operator{
    background: linear-gradient(145deg, #0f9b0f, #0a690a);
    color: #fff;
}

.equalBtn{
    background: linear-gradient(145deg, #ff512f, #dd2476);
    color: #fff;
    font-weight: bold;
    box-shadow: 0px 5px 15px rgba(255, 81, 47, 0.6);
}

.equalBtn:hover{
    transform: scale(1.1);
    background: linear-gradient(145deg, #ff6a3d, #e94057);
}

.signature{
    text-align: center;
    margin-top: 12px;
    font-size: 13px;
    font-style: italic;
    font-weight: bold;
    color: rgba(255, 255, 255, 0.7);
    text-shadow: 0 0 4px rgba(255,255,255,0.2);
}

@media (max-width: 480px){
    input{
        font-size: 24px;
        padding: 15px;
    }

    button{
        height: 55px;
        font-size: 16px;
    }

    .calc-title{
        font-size: 22px;
    }
}