style.css

* {
    padding: 0;
    margin: 0;
}

body {
    height: 100vh;
    background: #2CA9DC;
    background: -webkit-radial-gradient(top left, #2CA9DC, #A4FCEC);
    background: -moz-radial-gradient(top left, #2CA9DC, #A4FCEC);
    background: radial-gradient(to bottom right, #2CA9DC, #A4FCEC);
}

ul,
li,
a {
    text-decoration: none;
    list-style: none;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: #fff;
    margin-bottom: 3rem;
}
ul {
    display: flex;
    gap: 1rem;
}

main {
    margin: 0 auto;
    color: black;
    width: 31.25rem;
    height: 70vh;
}

header {
    background: white;
    margin: 0.5rem 0;
    text-align: center;
    padding: 1rem;
}

form {
    display: flex;
    flex-direction: column;
    margin: 0 auto;
    background: white;
    padding: 1rem;
}
input {
    height: 30px;
    padding: 0 8px;
    border: 1px solid black;
    border-radius: 0.5rem;
    margin: 12px 0;
    font-size: 14px;
}
input[type=submit] {
    background: #2CA9DC;
    height: 3rem;
    cursor: pointer;
}
input[type=submit]:hover {
    background: rgb(44, 169, 220,0.6);
}
.erro {
    color: #ff0000;
}