JSFiddle - React, Tailwind, and code Playground

HTML

<label for="settings_pass_old"><span>Старый пароль</span></label><br />
                <input type="password" class="settings_input"  id="settings_pass_old"/><br />
                <label for="settings_pass_new"><span>Новый пароль</span></label><br />
                <input type="password" class="settings_input"  id="settings_pass_new"/><br />
                <button type="submit" class="settings_button">Сохранить (активная)</button><br /><br />
                <div class="settings_button settings_button_locked">Сохранить (неактивная)</div>

CSS

.settings_button { background:green}
.settings_button_locked {background:gray; width:250px;}