Darkness

$(document).ready(function() {
  $('.class-email').blur(function() {
    if($(this).val() != '') {
      var pattern = /^([a-z0-9_\.-])+@[a-z0-9-]+\.([a-z]{2,4}\.)?[a-z]{2,4}$/i;
      if(pattern.test($(this).val())){
        $(this).removeClass('error');
        $('#valid').text(''); 
      } else {
        $(this).addClass('error');  
        $('#valid').text('The field is required.');
      }
    }
  });
});

button, 
button:active, 
button:focus {
    outline: none;
}

const inputSelector = '#icons_care';
const checkboxSelector = '.check_care';
const checkboxCheckedSelector = `${checkboxSelector}:checked`;
const dataAttr = 'icon';
const separator = ', ';

$(document).on('change', checkboxSelector, () => {
  $(inputSelector).val($(checkboxCheckedSelector)
    .get()
    .map(n => $(n).data(dataAttr))
    .join(separator)
  );
});

// или

document.addEventListener('change', e => {
  if (e.target.matches(checkboxSelector)) {
    const input = document.querySelector(inputSelector);
    const cb = document.querySelectorAll(checkboxCheckedSelector);
    input.value = Array.from(cb, n => n.dataset[dataAttr]).join(separator);
  }
});