<label for="url">Уведіть URL, почавши з "https://":</label>

<input type="url" name="url" id="url" placeholder="https://example.com" pattern="https://.*" size="30" required />

label {
    display: block;
    font: 1rem 'Fira Sans', sans-serif;
}

input,
label {
    margin: 0.4rem 0;
}