style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    background-color: #f8f8f8;
    font-family: 'Montserrat', sans-serif;
}
.mainContainer{
    display: flex;
    height: 100vh;
    align-items: center;
    flex-direction: column;
    justify-content: center;
}
.logo{
    display: flex;
    margin-top: -10px;
    align-items: center;
    flex-direction: column;
    justify-content: center;
}
.logo h1{
    width: 300px;
    color: silver;
    text-align: center;
}
.logo svg , .logo h1{
    margin: 5px;
}
.userName{
    display: none;
    padding: 55px;
    position: fixed;
    border-radius: 5px;
    align-items: center;
    justify-content: center;
    background-color: #fff;
    box-shadow: 0px 0px 10px 0px rgba(0, 0, 0, 0.1);
}
.show{
    display: flex !important;
}

/* input filed code */
:root {
    background: #f5f6fa;
    color: #9c9c9c;
    font: 1rem "PT Sans", sans-serif;
}
.container {
    height: 100%;
}
  
a {
    color: inherit;
}
a:hover {
    color: #7f8ff4;
}
  
.container {
    display: -webkit-box;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
            flex-direction: column;
    -webkit-box-align: center;
            align-items: center;
    -webkit-box-pack: center;
            justify-content: center;
}
  
.uppercase {
    text-transform: uppercase;
}
  
.btn {
    display: inline-block;
    background: transparent;
    color: inherit;
    font: inherit;
    border: 0;
    outline: 0;
    padding: 0;
    -webkit-transition: all 200ms ease-in;
    transition: all 200ms ease-in;
    cursor: pointer;
}
.btn--primary {
    background: #5fcef3;
    color: #fff;
    box-shadow: 0 0 10px 2px rgba(0, 0, 0, 0.1);
    border-radius: 2px;
    padding: 12px 36px;
}
.btn--primary:hover {
    background: #54c9f0;
}
.btn--primary:active {
    background: #5fcef3;
    box-shadow: inset 0 0 10px 2px rgba(0, 0, 0, 0.1);
}
.btn--inside {
    margin-left: -96px;
} 
.form__field {
    width: 360px;
    background: #fff;
    color: #a3a3a3;
    font: inherit;
    box-shadow: 0 6px 10px 0 rgba(0, 0, 0, 0.1);
    border: 0;
    outline: 0;
    padding: 22px 18px;
}

/* Media Query */
@media only screen and (max-width:310px){
    .logo h1{
        width: auto;
        font-size: 1.4rem !important;
    }
}
@media only screen and (max-width:520px){
    .userName{
        height: 170px;
        padding: 20px;
    }
    .form__field{
        max-width: 300px;
    }
    .btn--primary{
        margin-left: -80px;
        padding: 10px 26px;
    }
}
@media only screen and (max-width:375px){
    .userName{
        width: 290px;
        height: 170px;
        margin: 0 !important;
        padding: 0 !important;
    }
    .form__field{
        margin-left: 0 !important;
        width: 250px !important;
    }
    .btn--primary{
        padding: 8px 12px;
    }
}