style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&display=swap');

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
    text-decoration: none;
}

html, body{
    height: 100%;
    width: 100%;
    background: #262a2f;
    font-family: "poppins", sans-serif;
}

.container{
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    max-width: 400px;
    width: 90%;
    background-color: #fff;
    padding: 25px 35px;
    border-radius: 10px;
}

.container p{
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 8px;
}

#input{
    width: 100%;
    border: 1px solid #494eea;
    height: 50px;
    border-radius: 5px;
    padding: 20px 10px;
    font-size: 15px;
    margin: 10px 0 20px;
}

.btn{
    width: 100%;
    height: 50px;
    color: #fff;
    font-size: 16px;
    font-weight: 500;
    background-color: #494eea;
    border: 0;
    border-radius: 7px;
    margin: 20px 0px;
    cursor: pointer;
    box-shadow: 0 10px 10px rgba(0,0,0,0.1);
}

#image-box{
    width: 200px;
    border-radius: 5px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 1s;
}

#image-box img{
    width: 100%;
    padding: 10px;
}

#image-box.show-img{
    max-height: 300px;
    margin: 10px auto;
    border: 1px solid #d1d1d1;
}

#download{
    display: none;
}

.error{
    animation: shake 0.1s linear 10;
}

@keyframes shake{
    0%{
        transform: translateX(0);
    }
    25%{
        transform: translateX(-2px);
    }
    50%{
        transform: translateX(0);
    }
    100%{
        transform: translateX(2px);
    }
}