Foro en construcción (HTML/mod_login)

<!-- BEGIN switch_login_small -->
<div class="formlogin" style="display:none;">
<form action="{S_LOGIN_ACTION}" method="post">
  <label for="username">{L_USERNAME}:</label>
  <input type="text" name="username" id="username" size="15" maxlength="40" value="{USERNAME}" class="inputbox autowidth" />
  <label for="password">{L_PASSWORD}:</label>
  <input type="password" id="password" name="password" size="15" maxlength="25" class="inputbox autowidth" />
  <div class="formbotones">
  <input type="checkbox" name="autologin" id="autologin" tabindex="4" class="checkbox" {AUTOLOGIN_CHECKED} /><label for="autologin">ENTRAR AUTOMÁTICAMENTE</label>
  <a href="{U_SEND_PASSWORD}" rel="nofollow" class="formsendpass">RECUPERAR CONTRASEÑA</a>
  </div>
  <input type="submit" name="login" tabindex="6" value="{L_LOGIN}" class="button1" />
</form>
<style>body#phpbb.invibody {--bckg0: #00049a;--bckg1: #fafafa;--bckg2: #fff;--bradius: 20px;--title: #00049a;--text: #777;}

body#phpbb.invibody {
    background: var(--bckg0);
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

.construcción {
    border-radius: var(--bradius);
    background: var(--dbckg1);
    padding: 20px;
    width: 300px;
}

.cnheader {
    color: var(--title);
    font: 14px 'Poppins';
    text-transform: uppercase;
    font-weight: 700;
    text-align: justify;
    text-align-last: center;
}

.cntexto {
    width: 100%;
    max-height: 200px;
    overflow: auto;
    font-size: 12px;
    margin-top: 5px;
    margin-bottom: 20px;
    color: var(--text);
    text-align: justify;
}

.cnform {
    background: var(--bckg2);
    border-radius: var(--bradius);
    padding: 20px;
}

.cnheader2 {
    background: var(--bckg0);
    color: #fff;
    margin: -20px -20px 20px;
    border-radius: var(--bradius) var(--bradius) 0 0;
    padding: 10px 10px 10px 20px;
    font: 12px 'Poppins';
}

form label {
    font: 10px 'Poppins';
    text-transform: uppercase;
    font-weight: 700;
    color: var(--bckg0);
    display: block;
}

input#username.inputbox, input#password.inputbox {
    margin-bottom: 10px;
    width: 100%!important;
    border: 0;
    border-radius: var(--bradius);
    font-size: 12px;
    color: var(--text);
    background: rgba(0,0,0,0.07);
}

.formbotones {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 10px;
}

input#autologin {
    display: none;
}

.formbotones label, .formbotones a {
    text-align: center;
    font: 10px 'Poppins';
    text-transform: uppercase;
    font-weight: 700;
    color: var(--bckg0);
    display: flex;
    width: 100%;
    background: rgba(0,0,0,0.07);
    align-self: stretch;
    padding: 5px;
    justify-content: center;
    align-items: center;
    border-radius: var(--bradius);
}

.formbotones label {
    margin-right: 5px;
  cursor:pointer;
}

input.checkbox:checked + label[for="autologin"] { font-style:italic; }

.construcción input.button1 {
    text-align: center;
    font: 10px 'Poppins';
    text-transform: uppercase;
    font-weight: 700;
    background: var(--bckg0);
    display: block;
    width: 100%!important;
    color: #fff;
    align-self: stretch;
    padding: 5px;
    border-radius: var(--bradius);
    border: 0;
    text-shadow: 0 0 transparent;
}
.construcción input.button1:hover {
    color: white;
    font-style: italic;
    border: 0;
}</style>
<link href="https://fonts.googleapis.com/css2?family=Poppins:ital,wght@0,700;1,700&display=swap" rel="stylesheet"/>
</div>
<!-- END switch_login_small -->