Form

/* ------------------------------------ */
/* Estilos para elementos de formulario */
/* ------------------------------------ */

.form {


  /* Estilos para el fieldset */
  & fieldset {
    border: 1px solid #ced4da;
    border-radius: 0.25rem;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    background: linear-gradient(to right, #f5f5f5, #fff);

    & legend {
      font-weight: 600;
      color: #495057;
      padding: .5rem 1rem;
      margin-bottom: 1rem;
      border: 1px solid #ced4da;
      border-radius: 0.25rem;
      background: linear-gradient(to right, #f5f5f5, #fff)
    }
  }


  /* Etiquetas de los formularios */
  & label,
  & .group-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #495057;
  }

  & .group-label {
    margin-bottom: 1.5rem;
  }

  /* Campos de entrada de texto */
  & input:not([type="radio"]):not([type="checkbox"]),
  & select,
  & textarea {
    display: block;
    width: 100%;
    padding: 0.375rem 0.75rem;
    font-size: 1rem;
    line-height: 1.5;
    color: #495057;
    background-color: #fff;
    background-clip: padding-box;
    border: 1px solid #ced4da;
    border-radius: 0.25rem;
    transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
  }

  /* Estilos para el campo de texto en foco */
  & input:not([type="radio"]):not([type="checkbox"]):focus,
  & select:focus,
  & textarea:focus {
    border-color: #80bdff;
    outline: none;
    box-shadow: 0 0 0 0.1rem rgba(0, 123, 255, 0.25);
  }

  /* Select */
  & select:not([multiple]) {
    height: auto;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 10 10'%3E%3Cpath fill='%23495057' d='M5 7L2 3h6L5 7z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    background-size: 1rem;
  }

  & select[multiple] {
    height: auto;
    padding: 0.375rem;

    & option {
      padding: 0.375rem;

      &:checked {
        color: #000;
        background: #f5f5f5;
        border-radius: 0.25rem;
      }
    }
  }

  /* textarea */
  & textarea {
    resize: vertical;
  }


  /* agrupa los elementos de un campo */
  & .form-group {
    margin-bottom: 1.5rem;

    &:last-child {
      padding-bottom: 0;
      margin-bottom: 0;
    }
  }

  /* Fila flexible para organizar elementos en la misma línea */
  & .form-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-bottom: 1.5rem;

    &:last-child {
      padding-bottom: 0;
      margin-bottom: 0;
    }
  }

  /* Columna flexible para organizar elementos en la misma columna */
  & .form-col {
    flex: 1;
    min-width: 15rem;
  }

  /* Estilo para el contenedor input-group */
  & .input-group {
    display: flex;
    flex-direction: row;
    align-items: stretch;
    width: 100%;

    & .input-group-text {
      flex-shrink: 0;
      padding: 0.375rem 0.75rem;
      font-size: 1rem;
      font-weight: 400;
      line-height: 1.5;
      color: #495057;
      white-space: nowrap;
      background-color: #e9ecef;
      border: 1px solid #ced4da;
      border-radius: 0.25rem;
    }

    & input,
    & select {
      flex: 1;
      /* Ocupa todo el espacio disponible */
      z-index: 1;
    }

    & .input-group-prepend {
      margin-right: -1px;
      border-top-right-radius: 0;
      border-bottom-right-radius: 0;
      z-index: 0;
    }

    &>input:not(:first-child),
    &>select:not(:first-child) {
      border-top-left-radius: 0;
      border-bottom-left-radius: 0;
    }

    & .input-group-append {
      margin-left: -1px;
      border-top-left-radius: 0;
      border-bottom-left-radius: 0;
      z-index: 0;
    }

    &>input:not(:last-child),
    &>select:not(:last-child) {
      border-top-right-radius: 0;
      border-bottom-right-radius: 0;
    }

  }


  /* Estilos generales para campos de formulario válidos e inválidos */
  & input:not([type="radio"]):not([type="checkbox"]),
  &.was-validated input:not([type="radio"]):not([type="checkbox"]),
  & select,
  &.was-validated select,
  & textarea,
  &.was-validated textarea {

    background-repeat: no-repeat;
    background-position: right calc(.375em + .1875rem) center;
    background-size: calc(.75em + .375rem) calc(.75em + .375rem);

    &.is-valid {
      padding-right: calc(1.5em + .75rem);
      border-color: #28a745;
      background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 8 8'%3e%3cpath fill='%2328a745' d='M2.3 6.73L.6 4.53c-.4-1.04.46-1.4 1.1-.8l1.1 1.4 3.4-3.8c.6-.63 1.6-.27 1.2.7l-4 4.6c-.43.5-.8.4-1.1.1z'/%3e%3c/svg%3e");

      &:focus {
        border-color: #28a745;
        box-shadow: 0 0 0 0.1rem rgba(40, 167, 69, 0.25);
      }
    }

    &.is-invalid {
      padding-right: calc(1.5em + .75rem);
      border-color: #dc3545;
      background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 12' width='12' height='12' fill='none' stroke='%23dc3545'%3e%3ccircle cx='6' cy='6' r='4.5'/%3e%3cpath stroke-linejoin='round' d='M5.8 3.6h.4L6 6.5z'/%3e%3ccircle cx='6' cy='8.2' r='.6' fill='%23dc3545' stroke='none'/%3e%3c/svg%3e");

      &:focus {
        border-color: #dc3545;
        box-shadow: 0 0 0 0.1rem rgba(220, 53, 69, 0.25);
      }
    }

    &:focus {
      outline: none;
    }

  }



  /* Estilos para agrupar campos de tipo radio y checkbox */
  & .radio-group,
  & .checkbox-group {
    display: flex;
    flex-direction: column;
    gap: .2rem;
    flex-wrap: wrap;

    &.radio-group-inline,
    &.checkbox-group-inline {
      flex-direction: row;
      gap: 1.5rem;
    }

    & label {
      display: flex;
      flex-direction: row;
      align-items: center;
      gap: .75rem;

      & span {
        font-weight: normal;
        color: #6c757d;
      }
    }
  }

  /* Estilos para campos de tipo radio */
  & input[type="radio"] {

    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    width: 1rem;
    height: 1rem;
    border: 1px solid #6c757d;
    border-radius: 50%;
    outline: none;
    cursor: pointer;
    position: relative;

    &:checked::before {
      content: '';
      width: .5em;
      height: .5em;
      border-radius: 50%;
      background-color: #6c757d;
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
    }
  }

  /* Estilos para campos de tipo checkbox */
  & input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    width: 1rem;
    height: 1rem;
    border: 1px solid #6c757d;
    border-radius: .25rem;
    outline: none;
    cursor: pointer;
    position: relative;
    background-color: #fff;
    transition: background-color 0.3s, border-color 0.3s;

    &:checked {
      background-color: #fff;
      border-color: #6c757d;

      &::before {
        content: '';
        width: .65em;
        height: .65em;
        background-color: #6c757d;
        border-radius: .2em;
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
      }
    }
  }

  /*
  & input[type="radio"],
  & input[type="checkbox"] {

    &.is-valid:checked {
       border-color: #28a745;
        &+span {
          color: #28a745;
        }
        &:checked::before {
          background-color: #28a745;
        } 
    }

    &.is-invalid {
       border-color: #dc3545;
        &+span {
          color: #dc3545;
        } 
    }
  }*/



  /* Ayuda de texto */
  & .form-text {
    display: block;
    margin-top: 0.25rem;
    color: #6c757d;
    font-size: 0.875rem;
  }

  /* Estilos para mensajes de validación */
  & .invalid-feedback {
    width: 100%;
    margin-top: .25rem;
    font-size: .875rem;
    color: #dc3545;
  }

  /* Estilos para campos de formulario deshabilitados */
  & input:disabled {
    background-color: #ffffff !important;
    cursor: not-allowed !important;
    opacity: 0.65 !important;
  }



}

<form class="form">
    <fieldset>

        <legend>Legend</legend>

        <div class="form-group">
            <label for="input-field">Input</label>
            <input type="text" id="input-field" name="inputField" maxlength="10" required>
        </div>

        <div class="form-row">

            <div class="form-col">
                <label for="input-number-field">Input Número</label>
                <input type="number" id="input-number-field" name="inputNumberField" min="0" max="100" step="0.01"
                    required>
            </div>

            <div class="form-col">
                <label for="input-telephone-field">Input Teléfono</label>
                <input type="tel" id="input-telephone-field" name="inputTelephoneField" maxlength="15" required>
            </div>

        </div>

        <div class="form-row">

            <div class="form-col">
                <label for="input-date-field">Input Fecha</label>
                <input type="date" id="input-date-field" name="inputDateField" min="1990-01-01" max="9999-12-31"
                    required>
            </div>

            <div class="form-col">
                <label for="input-time-field">Input Hora</label>
                <input type="time" id="input-time-field" name="inputTimeField" required>
            </div>

        </div>

        <div class="form-group">
            <label for="textarea-field">Textarea</label>
            <textarea id="textarea-field" name="textareaField" rows="4" required></textarea>
        </div>

        <div class="form-group">
            <label for="select-field">Select</label>
            <select id="select-field" name="selectField" required>
                <option value="option1">Option 1</option>
                <option value="option2" selected>Option 2</option>
                <option value="option3">Option 3</option>
                <option value="option4">Option 4</option>
            </select>
        </div>

        <div class="form-group">
            <label for="select-field">Select Múltiple</label>
            <select id="select-field" name="selectField" multiple required>
                <option value="option1">Option 1</option>
                <option value="option2" selected>Option 2</option>
                <option value="option3">Option 3</option>
                <option value="option4">Option 4</option>
            </select>
        </div>

        <div class="form-row">

            <div class="form-col">
                <div class="group-label">Radio buttons verticales</div>
                <div class="radio-group" role="radiogroup" aria-labelledby="labelVertical">
                    <label>
                        <input type="radio" name="option-vertical" value="1">
                        <span>Opción 1</span>
                    </label>
                    <label>
                        <input type="radio" name="option-vertical" value="2">
                        <span>Opción 2</span>
                    </label>
                    <label>
                        <input type="radio" name="option-vertical" value="3">
                        <span>Opción 3</span>
                    </label>
                </div>
            </div>

            <div class="form-col">
                <div class="group-label">Radio buttons en linea</div>
                <div class="radio-group radio-group-inline" role="radiogroup" aria-labelledby="labelInline">
                    <label>
                        <input type="radio" name="option-inline" value="1">
                        <span>Opción 1</span>
                    </label>
                    <label>
                        <input type="radio" name="option-inline" value="2">
                        <span>Opción 2</span>
                    </label>
                    <label>
                        <input type="radio" name="option-inline" value="3">
                        <span>Opción 3</span>
                    </label>
                </div>
            </div>

        </div>

    </fieldset>


</form>