body {
    font-family: tahoma;
    background: #f3f6fb;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.card {
    background: #fff;
    padding: 28px 30px 24px;
    border-radius: 14px;
    width: 360px;
    box-shadow: 0 12px 30px rgba(0, 0, 0, .12);
    text-align: center;
}

h3 {
    margin: 0 0 16px
}

input {
    width: 100%;
    padding: 11px 12px;
    margin: 8px 0;
    border-radius: 8px;
    border: 1px solid #ddd;
    outline: none;
    font-size: 14px;
}

input:focus {
    border-color: #28a745;
    box-shadow: 0 0 0 2px rgba(40, 167, 69, .15)
}

.rules {
    text-align: left;
    font-size: 13px;
    margin: 10px 0 12px;
}

.rules li {
    color: #c0392b;
    margin: 4px 0
}

.rules li.ok {
    color: #27ae60;
    font-weight: bold
}

button {
    width: 100%;
    padding: 11px;
    border: none;
    border-radius: 8px;
    background: #bdbdbd;
    color: #fff;
    cursor: not-allowed;
    font-size: 15px;
}

button.enabled {
    background: #28a745;
    cursor: pointer;
}

.error {
    color: #c0392b;
    margin-top: 8px
}