formvalidation.css

@import url('https://fonts.googleapis.com/css2?family=Lato:wght@300;400;700&display=swap');

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

.container{
    width: 100%;
    height: 100vh;
    background: #c7ebc7;
    display: flex;
    align-items: center;
    justify-content: center;
}

.container form{
    width: 90%;
    max-width: 500px;
    padding: 50px 30px 20px;
    background: #fff;
    border-radius: 5px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.5);
    position: relative;
}

.container .fa-envelope{
    position: absolute;
    top: 0;
    left: 50%;
    transform: translate(-50%,-50%);
    background: #fff;
    font-size: 26px;
    border-radius: 50%;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

.container .input-box{
    width: 100%;
    display: flex;
    align-items: center;
    position: relative;
    margin: 10px 0;
}

.container .input-box label{
    flex-basis: 28%;
}

.container .input-box input, .container .input-box textarea{
    flex-basis: 68%;
    background: transparent;
    border: 0;
    outline: 0;
    padding: 10px 0;
    border-bottom: 1px solid #999;
    color: #333;
    font-size: 16px;
}

.container .input-box input::placeholder{
    font-size: 14px;
}

.container .btn{
    background: #2b46c0;
    color: #fff;
    border-radius: 5px;
    border: 1px solid rgba(255, 255, 255, 0.7);
    padding: 10px 20px;
    outline: 0;
    cursor: pointer;
    display: block;
    margin: 30px auto 10px;
    transition: all 0.5s ease;
    text-transform: uppercase;
}

.container .btn:hover{
    background: #0f2fbe;
}

.container .input-box span{
    position: absolute;
    right: 17px;
    bottom: 12px;
    font-size: 14px;
    color: #ff0000;
}

.container  #submit-error{
    color: #ff0000;
}

.container .input-box .fa-check{
    color: #2e8b57;
    background-color: #e2dcdc;
    border-radius: 50%;
    padding: 7%;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

.container .popup{
    width: 400px;
    background: #fff;
    border-radius: 6px;
    position: absolute;
    top: 0;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.1);
    text-align: center;
    padding: 0 30px 30px;
    color: #333;
    visibility: hidden;
    transition: transform 0.4s, top 4s;
}
.container .popup .fa-check{
    background: #fff;
    font-size: 26px;
    border-radius: 50%;
    padding: 20px;
    margin-bottom: 30px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

.container .open-popup{
    visibility: visible;
    top: 50%;
    transform: translate(-50%, -50%) scale(1);
}