page.css

* {
    margin: 0;
    padding: 0;
}

.box {
    text-align: center;
    width: 390px;
    height: 470px;
    margin: 100px auto;
    background: rgba(102, 222, 235, 0.5);
    border-radius: 15px;
}

.box img {
    width: 100px;
    height: 100px;
    display: block;
    margin-left: auto;
    margin-right: auto;
}

.box h1 {
    height: 77px;
    margin-top: 35px;
    text-align: center;
    font-size: 30px;
}

.box input {
    width: 356px;
    height: 50px;
    border:none;
    outline: none;
    border-bottom: 2px solid black;
    padding-left: 15px;
    margin-bottom: 14px;
    box-sizing: border-box;
    background-color:rgba(255,255,255,0);
}

.box button {
    width: 356px;
    height: 50px;
    background-color: skyblue;
    color: #fff;
    border: none;
}

input:focus {
    width: 356px;
    height: 50px;
    border:none;
    outline: none;
    border-bottom: 2px solid green;
    padding-left: 15px;
    margin-bottom: 14px;
    box-sizing: border-box;
    background-color:rgba(255,255,255,0);
}