radio_buttons.haml

.square-radio
  = radio_button_tag :promotion_length, 7, id: 'promotion_length_7'
  = label_tag 'promotion_length_7', 'Promuj przez 7 dni cena: 450 złotych'
.square-radio
  = radio_button_tag :promotion_length, 14, id: 'promotion_length_14'
  = label_tag 'promotion_length_14', 'Promuj przez 14'
.square-radio
  = radio_button_tag :promotion_length, 28, id: 'promotion_length_28'
  = label_tag 'promotion_length_28', 'Promuj przez 28'

radio_buttons.scss

.square-radio {
  margin-bottom: 15px;

  label {
    cursor: pointer;
    display: inline-block;
    font-size: 13px;
    margin-right: 15px;
    padding-left: 35px;
    position: relative;
    width: 260px;

    &:before {
      border: 2px solid #c2c1c1;
      content: '';
      display: inline-block;
      height: 20px;
      left: 0;
      position: absolute;
      width: 20px;
    }
  }

  input[type=radio] {
    display: none;
  }

  input[type=radio]:checked + label:before {
    color: #d5b45e;
    content: '\2713';
    font-size: 15px;
    line-height: 20px;
    text-align: center;
  }
}