Bootstrap/less/forms.less

//
// Forms
// --------------------------------------------------


// Normalize non-controls
//
// Restyle and baseline non-control form elements.

fieldset {
  padding: 0;
  margin: 0;
  border: 0;
}

legend {
  display: block;
  width: 100%;
  padding: 0;
  margin-bottom: @line-height-computed;
  font-size: (@font-size-base * 1.5);
  line-height: inherit;
  color: @gray-dark;
  border: 0;
  border-bottom: 1px solid @legend-border-color;
}

label {
  display: inline-block;
  margin-bottom: 5px;
  font-weight: bold;
}


// Normalize form controls

// Override content-box in Normalize (* isn't specific enough)
input[type="search"] {
  .box-sizing(border-box);
}

// Position radios and checkboxes better
input[type="radio"],
input[type="checkbox"] {
  margin: 4px 0 0;
  margin-top: 1px \9; /* IE8-9 */
  line-height: normal;
}

// Set the height of select and file controls to match text inputs
input[type="file"] {
  display: block;
}

// Make multiple select elements height not fixed
select[multiple],
select[size] {
  height: auto;
}

// Fix optgroup Firefox bug per https://github.com/twbs/bootstrap/issues/7611
select optgroup {
  font-size: inherit;
  font-style: inherit;
  font-family: inherit;
}

// Focus for select, file, radio, and checkbox
input[type="file"]:focus,
input[type="radio"]:focus,
input[type="checkbox"]:focus {
  .tab-focus();
}

// Fix for Chrome number input
// Setting certain font-sizes causes the `I` bar to appear on hover of the bottom increment button.
// See https://github.com/twbs/bootstrap/issues/8350 for more.
input[type="number"] {
  &::-webkit-outer-spin-button,
  &::-webkit-inner-spin-button {
    height: auto;
  }
}


// Placeholder
//
// Placeholder text gets special styles because when browsers invalidate entire
// lines if it doesn't understand a selector/
.form-control {
  .placeholder();
}


// Common form controls
//
// Shared size and type resets for form controls. Apply `.form-control` to any
// of the following form controls:
//
// select
// textarea
// input[type="text"]
// input[type="password"]
// input[type="datetime"]
// input[type="datetime-local"]
// input[type="date"]
// input[type="month"]
// input[type="time"]
// input[type="week"]
// input[type="number"]
// input[type="email"]
// input[type="url"]
// input[type="search"]
// input[type="tel"]
// input[type="color"]

.form-control {
  display: block;
  width: 100%;
  height: @input-height-base; // Make inputs at least the height of their button counterpart (base line-height + padding + border)
  padding: @padding-base-vertical @padding-base-horizontal;
  font-size: @font-size-base;
  line-height: @line-height-base;
  color: @gray;
  vertical-align: middle;
  background-color: @input-bg;
  border: 1px solid @input-border;
  border-radius: @input-border-radius;
  .box-shadow(inset 0 1px 1px rgba(0,0,0,.075));
  .transition(~"border-color ease-in-out .15s, box-shadow ease-in-out .15s");

  // Customize the `:focus` state to imitate native WebKit styles.
  .form-control-focus();

  // Disabled and read-only inputs
  // Note: HTML5 says that inputs under a fieldset > legend:first-child won't be
  //   disabled if the fieldset is disabled. Due to implementation difficulty,
  //   we don't honor that edge case; we style them as disabled anyway.
  &[disabled],
  &[readonly],
  fieldset[disabled] & {
    cursor: not-allowed;
    background-color: @input-bg-disabled;
  }

  // Reset height for `textarea`s
  textarea& {
    height: auto;
  }
}


// Form groups
//
// Designed to help with the organization and spacing of vertical forms. For
// horizontal forms, use the predefined grid classes.

.form-group {
  margin-bottom: 15px;
}


// Checkboxes and radios
//
// Indent the labels to position radios/checkboxes as hanging controls.

.radio,
.checkbox {
  display: block;
  min-height: @line-height-computed; // clear the floating input if there is no label text
  margin-top: 10px;
  margin-bottom: 10px;
  padding-left: 20px;
  vertical-align: middle;
  label {
    display: inline;
    margin-bottom: 0;
    font-weight: normal;
    cursor: pointer;
  }
}
.radio input[type="radio"],
.radio-inline input[type="radio"],
.checkbox input[type="checkbox"],
.checkbox-inline input[type="checkbox"] {
  float: left;
  margin-left: -20px;
}
.radio + .radio,
.checkbox + .checkbox {
  margin-top: -5px; // Move up sibling radios or checkboxes for tighter spacing
}

// Radios and checkboxes on same line
.radio-inline,
.checkbox-inline {
  display: inline-block;
  padding-left: 20px;
  margin-bottom: 0;
  vertical-align: middle;
  font-weight: normal;
  cursor: pointer;
}
.radio-inline + .radio-inline,
.checkbox-inline + .checkbox-inline {
  margin-top: 0;
  margin-left: 10px; // space out consecutive inline controls
}



// Form control sizing
//
// Relative text size, padding, and border-radii changes for form controls. For
// horizontal sizing, wrap controls in the predefined grid classes. `<select>`
// element gets special love because it's special, and that's a fact!

.input-lg {
  height: @input-height-large;
  padding: @padding-large-vertical @padding-large-horizontal;
  font-size: @font-size-large;
  line-height: @line-height-large;
  border-radius: @border-radius-large;
}
.input-sm {
  height: @input-height-small;
  padding: @padding-small-vertical @padding-small-horizontal;
  font-size: @font-size-small;
  line-height: @line-height-small;
  border-radius: @border-radius-small;
}

select {
  &.input-lg {
    height: @input-height-large;
    line-height: @input-height-large;
  }
  &.input-sm {
    height: @input-height-small;
    line-height: @input-height-small;
  }
}
textarea {
  &.input-lg,
  &.input-sm {
    height: auto;
  }
}


// Form control feedback states
//
// Apply contextual and semantic states to individual form controls.

// Warning
.has-warning {
  .form-control-validation(@state-warning-text; @state-warning-text; @state-warning-bg);
}
// Error
.has-error {
  .form-control-validation(@state-danger-text; @state-danger-text; @state-danger-bg);
}
// Success
.has-success {
  .form-control-validation(@state-success-text; @state-success-text; @state-success-bg);
}


// Help text
//
// Apply to any element you wish to create light text for placement immediately
// below a form control. Use for general help, formatting, or instructional text.

.help-block {
  display: block; // account for any element using help-block
  margin-top: 5px;
  margin-bottom: 10px;
  color: lighten(@text-color, 25%); // lighten the text some for contrast
}



// Inline forms
//
// Make forms appear inline(-block).

.form-inline {
  .form-control,
  .radio,
  .checkbox {
    display: inline-block;
  }
  .radio,
  .checkbox {
    margin-top: 0;
    margin-bottom: 0;
  }
}


// Horizontal forms
//
// Horizontal forms are built on grid classes and allow you to create forms with
// labels on the left and inputs on the right.

.form-horizontal .control-label,
.form-horizontal .radio-inline,
.form-horizontal .checkbox-inline {
  padding-top: 9px;
}

.form-horizontal {
  .form-group {
    .make-row();
  }
}

// Only right align form labels here when the columns stop stacking
@media (min-width: @screen-tablet) {
  .form-horizontal .control-label {
    text-align: right;
  }
}