nice forms // source http://jsbin.com/yutabo

index.html

<style id="jsbin-css">
.form {
  font-size: 1em;
  color: #4C4C35;
  box-sizing: border-box;
}

.form, .form * {
  box-sizing: border-box;
}

/* clearfix */
.form:before,
.form:after {
  content: ' ';
  display: table;
}
.form:after {
  clear: both;
}

.form fieldset {
  padding: 0;
  border: none;
  background: none;
  margin: 0;
}

.form input:-webkit-autofill {
  -webkit-box-shadow: 0 0 0px 1000px #F7F7F7 inset;
}

.form.submitting input[type="submit"] {
  pointer-events: none;
  color: #C7C7C7;
  background: #ebebeb;
  border: 1px solid #C7C7C7;
}

.form.submitting .focused {
  z-index: 0;
}

.form fieldset + fieldset {
  margin-top: 1em;
}

.form label.form-label {
  display: block;
  border-top: 0.0625em solid #E1E0E3; /* 1/16 */
  border-left: 0.0625em solid #E1E0E3; /* 1/16 */
  background-color: white;
  padding: 2.1em .8em .8em .8em;
  position: relative;
  float: left;
  width: 100%;

  /* border-collapse trick */
  box-shadow:
    1px 0 0 0 #E1E0E3,
    0 1px 0 0 #E1E0E3,
    1px 1px 0 0 #E1E0E3;   /* Just to fix the corner */
}

.form .form-label > i {
  position: absolute;
  right: 10px;
  top: 10px;
  color: #E1E0E3;
}

.form label.form-label[valid]:after,
.form label.form-label.focused:after,
.form label.form-label[invalid]:after {
  content: ' ';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
  pointer-events: none;
}

.form label.form-label[valid]:after {
  outline: 1px solid #6CCC50;
  z-index: 1;
}

.form label.form-label[valid] .label,
.form label.form-label[valid] i {
  color: #6CCC50;
}

.form label.form-label[invalid]:after {
  outline: 1px solid #FF654E;
  z-index: 2;
}

.form label.form-label[invalid] .label,
.form label.form-label[invalid] i {
  color: #FF654E;
}

.form label.form-label.focused:after {
  outline: 1px solid #00A0FF;
  z-index: 3;
}

.form label.form-label.focused .label,
.form label.form-label.focused i {
  color: #00A0FF;
}

.form .label {
  position: absolute;
  top: 1.075em;
  left: 1.3em;
  font-size: 0.7em;
  text-transform: uppercase;
  letter-spacing: 2px;
  font-family: 'efra', 'Helvetica Neue', Helvetica, sans-serif;
}

.form input[type=text],
.form input[type=password],
.form textarea {
  outline: none;
  background: none;
  width: 100%;
  font-size: 1em;
  letter-spacing: 1px;
  position: relative;
  border: 1px solid #EBEBEB;
}

.form label input[type=text],
.form label input[type=password],
.form label textarea {
  height: 1.8em;
  border: none;
  font-family: 'San Francisco', 'Helvetica Neue', Helvetica;
}

.form .form-label[checkbox] {
  padding: .8em;
  padding-left: 2.75em;
  user-select: none;
}

.form input[type='checkbox'] {
  display: none;
}

.form .checkmark-label {
  vertical-align: middle;
  position: relative;
  font-size: .85em;
}

.form .checkmark-visible {
  margin-left: -2.125em;
  float: left;
  position: relative;
  width: 1.5em;
  height: 1.5em;
  border: 2px solid #E1E0E3;
  border-radius: 50%;
}

.checkmark-visible:before {
  content: '';
  display: none;
  position: absolute;
  top: 50%;
  left: 50%;
  margin: -3px 0 0 -5px;
  height: 3px;
  width: 9px;
  border: solid #00A0FF;
  border-width: 0 0 2px 2px;
  transform: rotate(-45deg);
}
.form input[type='checkbox']:checked ~ .checkmark-visible {
  border-color: #00A0FF;
}
.form input[type='checkbox']:checked ~ .checkmark-visible:before {
  display: block;
}


.form .form-label[checkbox] {
  padding-top: .625em;
  padding-bottom: .625em;
}

.form .form-label[disabled] {
  cursor: not-allowed;
}

.form .form-label[disabled]:after {
  display: none;
}

.form .form-label[disabled] .label,
.form .form-label[disabled] i {
  color: #E1E0E3 !important;
}

.form .form-label[disabled] input,
.form .form-label[disabled] textarea {
  cursor: not-allowed;
  resize: none;
}

.form .form-label[checkbox][disabled] .checkmark-visible,
.form .form-label[checkbox][disabled] .checkmark-label {
  color: #E1E0E3;
  border-color: #FAFAFA;
}

.form textarea {
  min-height: 6.25em;
  resize: vertical;
}

.form .form-label.focused > i {
  color: #00A0FF;
}

.form input::placeholder,
.form textarea::placeholder {
  font-weight: 200;
  color: #c8c8c8;
}

/**
 * App specific
 */

.icon-markdown {
  display: block;
  padding: 10px;
  background: whiteSmoke;
  position: absolute;
  top: 10px;
  right: 10px;
}

/**
 * Positioning (with lemonade)
 */

.form .bit-75 {
  display: inline-block;
  width: 75%;
  float: left;
}

.form .bit-25 {
  display: inline-block;
  width: 25%;
  float: left;
}

/**
 * Validation Errors
 */

.form .validation-error-list {
  list-style-type: none;
}

.form .validation-error {
  border-bottom: 1px white solid;
  margin-right: -1px;
}

.form .validation-error h3 {
  text-align: left;
  color: white;
  background: #FF6447;
  line-height: 1.5;
  padding: 5px 20px;
}

.form .validation-message {
  font-weight: 300;
}

.Task-Create-container {
  max-width: 500px;
  width: 100%;
  margin: 50px auto;
  padding: 0 20px;
}

.Task-Create-create-button {
  margin-top: 40px;
  float: right;
}

.search-results-list li:first-of-type {
  padding-top: 80px;
}

.Task-Create-undecided > label[disabled] {
  display: block;
}

.Task-Create-undecided > label {
  display: block;
}

.Task-Create-undecided-checkbox:checked ~ .Task-Create-undecided-note {
  display: block;
}

.Task-Create-undecided-note {
  display: none;
  padding-top: 5px;
  font-size: .85em;
  /*color: #f7ba00;*/
  color: #00A0FF
}
</style>
<meta name="description" content="nice forms">
<form class="form Task-Create-form" action="/tasks" method="post" id="task-create-form">
  <div class="validation-errors"></div>
  <fieldset>
    <h3>What do you need done?</h3>
    <div class="bit-75">
      <label validate="validate" class="form-label"><span class="label">Task title</span>
        <input name="title" placeholder="I need a jQuery autocomplete plugin" class="Task-Create-title" type="text"/><span class="validation"></span>
      </label>
    </div>
    <div class="bit-25">
      <label validate="validate" class="form-label"><span class="label">Amount</span><i class="gt usd"></i>
        <input name="price" placeholder="150" type="text"/><span class="validation"></span>
      </label>
    </div>
  </fieldset>
  <fieldset>
    <h3>How should it be done?</h3>
    <label validate="validate" class="form-label"><span class="label">Task description</span><i class="gt markdown"></i>
      <textarea name="description" placeholder="description..."></textarea>
    </label>
  </fieldset>
  <fieldset>
    <h3>What library does it use?</h3>
    <div class="Task-Create-repositories">
      <label validate="validate" class="form-label"><span class="label">github repository</span><i class="gt github"></i>
        <input name="repositories" placeholder="jquery/jquery" id="task-create-repo" autocomplete="off" class="Task-Create-repository-input" type="text"/><span class="validation"></span>
      </label>
      <ul id="search-results"></ul>
    </div>
    <div class="Task-Create-undecided">
      <label validate="validate" checkbox="checkbox" class="form-label">
        <input name="undecided" class="Task-Create-undecided-checkbox" type="checkbox"/><span class="checkmark-visible"></span><span class="checkmark-label">I'm not sure, let the applicant suggest a repository for me.</span>
        <div class="Task-Create-undecided-note">Note: this may make your task harder to find</div>
      </label>
    </div>
  </fieldset>
  <button Create Task="Create Task" type="submit" class="Task-Create-create-button success"></button>
</form>
<script id="jsbin-source-html" type="text/html"><meta name="description" content="nice forms">
//- TODO: Classes should be top-level, the rest of the attributes
//- should be passed to the input.

mixin form()
  - var method = attributes.method && attributes.method.toLowerCase()
  - method = method && method != 'post' && method != 'get' && method
  - attributes.method = method ? 'post' : attributes.method
  form.form&attributes(attributes)
    .validation-errors
    if (csrf && attributes.method != 'get')
      input(type='hidden', name='_csrf', value= csrf)
    if (method)
      input(type='hidden', name='_method', value= method)
    block

mixin form-input(label)
  - attributes.type = attributes.type || 'text';
  label.form-label(disabled=attributes.disabled validate=attributes.validate)
    span.label= label
    block
    - attributes.validate = null;
    input&attributes(attributes)
    span.validation

mixin form-textarea(label)
  label.form-label(disabled=attributes.disabled validate=attributes.validate)
    span.label= label
    i.gt.markdown
    - attributes.validate = null;
    textarea&attributes(attributes)!= attributes.value && attributes.value.trim()

mixin form-checkbox(label)
  - attributes.type = 'checkbox'
  label.form-label(disabled=attributes.disabled validate=attributes.validate checkbox)
    - attributes.validate = null;
    input&attributes(attributes)
    span.checkmark-visible
    span.checkmark-label= label
    block

mixin form-errors(errors)
  ul.validation-error-list
    each error in errors
      li.validation-error
        h3
          span.validation-field= error.field
          span.validation-message= error.message
          
+form.Task-Create-form(action='/tasks', method='post' id='task-create-form')


  //- Task Title & Amount
  fieldset
    h3 What do you need done?
    .bit-75
      +form-input('Task title')(
        name = 'title'
        placeholder = 'I need a jQuery autocomplete plugin'
        validate
      ).Task-Create-title
    .bit-25
      +form-input('Amount')(name = 'price', placeholder ='150' validate)
        i.gt.usd


  //- Task description
  fieldset
    h3 How should it be done?
    +form-textarea('Task description')(
      name = 'description'
      placeholder='description...'
      validate
    ) We need a jQuery plugin for an autocomplete component


  //- Choose a repository
  fieldset
    h3 What library does it use?
    .Task-Create-repositories
      +form-input('github repository')(
        name='repositories'
        placeholder='jquery/jquery'
        id='task-create-repo'
        autocomplete='off'
        validate
      ).Task-Create-repository-input
        i.gt.github
      ul#search-results

    //- Cannot Decide
    .Task-Create-undecided
      +form-checkbox('I\'m not sure, let the applicant suggest a repository for me.')(
        name = 'undecided'
        checked = false
      
        validate
      ).Task-Create-undecided-checkbox
        .Task-Create-undecided-note Note: this may make your task harder to find
  button('Create Task')(type='submit').Task-Create-create-button.success</script>

<script id="jsbin-source-css" type="text/css">.form {
  font-size: 1em;
  color: #4C4C35;
  box-sizing: border-box;
}

.form, .form * {
  box-sizing: border-box;
}

/* clearfix */
.form:before,
.form:after {
  content: ' ';
  display: table;
}
.form:after {
  clear: both;
}

.form fieldset {
  padding: 0;
  border: none;
  background: none;
  margin: 0;
}

.form input:-webkit-autofill {
  -webkit-box-shadow: 0 0 0px 1000px #F7F7F7 inset;
}

.form.submitting input[type="submit"] {
  pointer-events: none;
  color: #C7C7C7;
  background: #ebebeb;
  border: 1px solid #C7C7C7;
}

.form.submitting .focused {
  z-index: 0;
}

.form fieldset + fieldset {
  margin-top: 1em;
}

.form label.form-label {
  display: block;
  border-top: 0.0625em solid #E1E0E3; /* 1/16 */
  border-left: 0.0625em solid #E1E0E3; /* 1/16 */
  background-color: white;
  padding: 2.1em .8em .8em .8em;
  position: relative;
  float: left;
  width: 100%;

  /* border-collapse trick */
  box-shadow:
    1px 0 0 0 #E1E0E3,
    0 1px 0 0 #E1E0E3,
    1px 1px 0 0 #E1E0E3;   /* Just to fix the corner */
}

.form .form-label > i {
  position: absolute;
  right: 10px;
  top: 10px;
  color: #E1E0E3;
}

.form label.form-label[valid]:after,
.form label.form-label.focused:after,
.form label.form-label[invalid]:after {
  content: ' ';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
  pointer-events: none;
}

.form label.form-label[valid]:after {
  outline: 1px solid #6CCC50;
  z-index: 1;
}

.form label.form-label[valid] .label,
.form label.form-label[valid] i {
  color: #6CCC50;
}

.form label.form-label[invalid]:after {
  outline: 1px solid #FF654E;
  z-index: 2;
}

.form label.form-label[invalid] .label,
.form label.form-label[invalid] i {
  color: #FF654E;
}

.form label.form-label.focused:after {
  outline: 1px solid #00A0FF;
  z-index: 3;
}

.form label.form-label.focused .label,
.form label.form-label.focused i {
  color: #00A0FF;
}

.form .label {
  position: absolute;
  top: 1.075em;
  left: 1.3em;
  font-size: 0.7em;
  text-transform: uppercase;
  letter-spacing: 2px;
  font-family: 'efra', 'Helvetica Neue', Helvetica, sans-serif;
}

.form input[type=text],
.form input[type=password],
.form textarea {
  outline: none;
  background: none;
  width: 100%;
  font-size: 1em;
  letter-spacing: 1px;
  position: relative;
  border: 1px solid #EBEBEB;
}

.form label input[type=text],
.form label input[type=password],
.form label textarea {
  height: 1.8em;
  border: none;
  font-family: 'San Francisco', 'Helvetica Neue', Helvetica;
}

.form .form-label[checkbox] {
  padding: .8em;
  padding-left: 2.75em;
  user-select: none;
}

.form input[type='checkbox'] {
  display: none;
}

.form .checkmark-label {
  vertical-align: middle;
  position: relative;
  font-size: .85em;
}

.form .checkmark-visible {
  margin-left: -2.125em;
  float: left;
  position: relative;
  width: 1.5em;
  height: 1.5em;
  border: 2px solid #E1E0E3;
  border-radius: 50%;
}

.checkmark-visible:before {
  content: '';
  display: none;
  position: absolute;
  top: 50%;
  left: 50%;
  margin: -3px 0 0 -5px;
  height: 3px;
  width: 9px;
  border: solid #00A0FF;
  border-width: 0 0 2px 2px;
  transform: rotate(-45deg);
}
.form input[type='checkbox']:checked ~ .checkmark-visible {
  border-color: #00A0FF;
}
.form input[type='checkbox']:checked ~ .checkmark-visible:before {
  display: block;
}


.form .form-label[checkbox] {
  padding-top: .625em;
  padding-bottom: .625em;
}

.form .form-label[disabled] {
  cursor: not-allowed;
}

.form .form-label[disabled]:after {
  display: none;
}

.form .form-label[disabled] .label,
.form .form-label[disabled] i {
  color: #E1E0E3 !important;
}

.form .form-label[disabled] input,
.form .form-label[disabled] textarea {
  cursor: not-allowed;
  resize: none;
}

.form .form-label[checkbox][disabled] .checkmark-visible,
.form .form-label[checkbox][disabled] .checkmark-label {
  color: #E1E0E3;
  border-color: #FAFAFA;
}

.form textarea {
  min-height: 6.25em;
  resize: vertical;
}

.form .form-label.focused > i {
  color: #00A0FF;
}

.form input::placeholder,
.form textarea::placeholder {
  font-weight: 200;
  color: #c8c8c8;
}

/**
 * App specific
 */

.icon-markdown {
  display: block;
  padding: 10px;
  background: whiteSmoke;
  position: absolute;
  top: 10px;
  right: 10px;
}

/**
 * Positioning (with lemonade)
 */

.form .bit-75 {
  display: inline-block;
  width: 75%;
  float: left;
}

.form .bit-25 {
  display: inline-block;
  width: 25%;
  float: left;
}

/**
 * Validation Errors
 */

.form .validation-error-list {
  list-style-type: none;
}

.form .validation-error {
  border-bottom: 1px white solid;
  margin-right: -1px;
}

.form .validation-error h3 {
  text-align: left;
  color: white;
  background: #FF6447;
  line-height: 1.5;
  padding: 5px 20px;
}

.form .validation-message {
  font-weight: 300;
}

.Task-Create-container {
  max-width: 500px;
  width: 100%;
  margin: 50px auto;
  padding: 0 20px;
}

.Task-Create-create-button {
  margin-top: 40px;
  float: right;
}

.search-results-list li:first-of-type {
  padding-top: 80px;
}

.Task-Create-undecided > label[disabled] {
  display: block;
}

.Task-Create-undecided > label {
  display: block;
}

.Task-Create-undecided-checkbox:checked ~ .Task-Create-undecided-note {
  display: block;
}

.Task-Create-undecided-note {
  display: none;
  padding-top: 5px;
  font-size: .85em;
  /*color: #f7ba00;*/
  color: #00A0FF
}</script>

jsbin.yutabo.css

.form {
  font-size: 1em;
  color: #4C4C35;
  box-sizing: border-box;
}

.form, .form * {
  box-sizing: border-box;
}

/* clearfix */
.form:before,
.form:after {
  content: ' ';
  display: table;
}
.form:after {
  clear: both;
}

.form fieldset {
  padding: 0;
  border: none;
  background: none;
  margin: 0;
}

.form input:-webkit-autofill {
  -webkit-box-shadow: 0 0 0px 1000px #F7F7F7 inset;
}

.form.submitting input[type="submit"] {
  pointer-events: none;
  color: #C7C7C7;
  background: #ebebeb;
  border: 1px solid #C7C7C7;
}

.form.submitting .focused {
  z-index: 0;
}

.form fieldset + fieldset {
  margin-top: 1em;
}

.form label.form-label {
  display: block;
  border-top: 0.0625em solid #E1E0E3; /* 1/16 */
  border-left: 0.0625em solid #E1E0E3; /* 1/16 */
  background-color: white;
  padding: 2.1em .8em .8em .8em;
  position: relative;
  float: left;
  width: 100%;

  /* border-collapse trick */
  box-shadow:
    1px 0 0 0 #E1E0E3,
    0 1px 0 0 #E1E0E3,
    1px 1px 0 0 #E1E0E3;   /* Just to fix the corner */
}

.form .form-label > i {
  position: absolute;
  right: 10px;
  top: 10px;
  color: #E1E0E3;
}

.form label.form-label[valid]:after,
.form label.form-label.focused:after,
.form label.form-label[invalid]:after {
  content: ' ';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
  pointer-events: none;
}

.form label.form-label[valid]:after {
  outline: 1px solid #6CCC50;
  z-index: 1;
}

.form label.form-label[valid] .label,
.form label.form-label[valid] i {
  color: #6CCC50;
}

.form label.form-label[invalid]:after {
  outline: 1px solid #FF654E;
  z-index: 2;
}

.form label.form-label[invalid] .label,
.form label.form-label[invalid] i {
  color: #FF654E;
}

.form label.form-label.focused:after {
  outline: 1px solid #00A0FF;
  z-index: 3;
}

.form label.form-label.focused .label,
.form label.form-label.focused i {
  color: #00A0FF;
}

.form .label {
  position: absolute;
  top: 1.075em;
  left: 1.3em;
  font-size: 0.7em;
  text-transform: uppercase;
  letter-spacing: 2px;
  font-family: 'efra', 'Helvetica Neue', Helvetica, sans-serif;
}

.form input[type=text],
.form input[type=password],
.form textarea {
  outline: none;
  background: none;
  width: 100%;
  font-size: 1em;
  letter-spacing: 1px;
  position: relative;
  border: 1px solid #EBEBEB;
}

.form label input[type=text],
.form label input[type=password],
.form label textarea {
  height: 1.8em;
  border: none;
  font-family: 'San Francisco', 'Helvetica Neue', Helvetica;
}

.form .form-label[checkbox] {
  padding: .8em;
  padding-left: 2.75em;
  user-select: none;
}

.form input[type='checkbox'] {
  display: none;
}

.form .checkmark-label {
  vertical-align: middle;
  position: relative;
  font-size: .85em;
}

.form .checkmark-visible {
  margin-left: -2.125em;
  float: left;
  position: relative;
  width: 1.5em;
  height: 1.5em;
  border: 2px solid #E1E0E3;
  border-radius: 50%;
}

.checkmark-visible:before {
  content: '';
  display: none;
  position: absolute;
  top: 50%;
  left: 50%;
  margin: -3px 0 0 -5px;
  height: 3px;
  width: 9px;
  border: solid #00A0FF;
  border-width: 0 0 2px 2px;
  transform: rotate(-45deg);
}
.form input[type='checkbox']:checked ~ .checkmark-visible {
  border-color: #00A0FF;
}
.form input[type='checkbox']:checked ~ .checkmark-visible:before {
  display: block;
}


.form .form-label[checkbox] {
  padding-top: .625em;
  padding-bottom: .625em;
}

.form .form-label[disabled] {
  cursor: not-allowed;
}

.form .form-label[disabled]:after {
  display: none;
}

.form .form-label[disabled] .label,
.form .form-label[disabled] i {
  color: #E1E0E3 !important;
}

.form .form-label[disabled] input,
.form .form-label[disabled] textarea {
  cursor: not-allowed;
  resize: none;
}

.form .form-label[checkbox][disabled] .checkmark-visible,
.form .form-label[checkbox][disabled] .checkmark-label {
  color: #E1E0E3;
  border-color: #FAFAFA;
}

.form textarea {
  min-height: 6.25em;
  resize: vertical;
}

.form .form-label.focused > i {
  color: #00A0FF;
}

.form input::placeholder,
.form textarea::placeholder {
  font-weight: 200;
  color: #c8c8c8;
}

/**
 * App specific
 */

.icon-markdown {
  display: block;
  padding: 10px;
  background: whiteSmoke;
  position: absolute;
  top: 10px;
  right: 10px;
}

/**
 * Positioning (with lemonade)
 */

.form .bit-75 {
  display: inline-block;
  width: 75%;
  float: left;
}

.form .bit-25 {
  display: inline-block;
  width: 25%;
  float: left;
}

/**
 * Validation Errors
 */

.form .validation-error-list {
  list-style-type: none;
}

.form .validation-error {
  border-bottom: 1px white solid;
  margin-right: -1px;
}

.form .validation-error h3 {
  text-align: left;
  color: white;
  background: #FF6447;
  line-height: 1.5;
  padding: 5px 20px;
}

.form .validation-message {
  font-weight: 300;
}

.Task-Create-container {
  max-width: 500px;
  width: 100%;
  margin: 50px auto;
  padding: 0 20px;
}

.Task-Create-create-button {
  margin-top: 40px;
  float: right;
}

.search-results-list li:first-of-type {
  padding-top: 80px;
}

.Task-Create-undecided > label[disabled] {
  display: block;
}

.Task-Create-undecided > label {
  display: block;
}

.Task-Create-undecided-checkbox:checked ~ .Task-Create-undecided-note {
  display: block;
}

.Task-Create-undecided-note {
  display: none;
  padding-top: 5px;
  font-size: .85em;
  /*color: #f7ba00;*/
  color: #00A0FF
}