/* ...existing code... */

#email-input,
#firstname-input,
#surname-input,
#password-input,
#dob-dummy,
#dateofbirth-input {
    border: none;
    border-bottom: 2px solid #007bff; /* You can adjust color and thickness */
    border-radius: 0;
    box-shadow: none;
}

/* ...existing code... */