HTML Form Layout CSS


Published: 2019-01-01
Updated: 2019-01-02
Web: https://fritzthecat-blog.blogspot.com/2019/01/html-form-layout-css.html


The HTML form element does nothing to arrange its subordinates in an appropriate layout. We must do it ourselves.
Such layout expectations could be specified as:

In this article I will introduce CSS implementing this. I won't yet cover the checkbox case, and also I won't think about "newspaper layout" (distributing label/field pairs across several columns when having a restricted height). You can visit the current state of this project on my homepage.

Form Sample

Here is a HTML form example that contains all fields available from HTML-5 browsers, so that we can examine whether the layout works for all types of fields. This is also to try out the field-features your browser provides.

E.g. Firefox doesn't support datetime-local, week, month fields by now.
Chrome supports all, but paints box-shadow for radio-buttons badly, and the default shape of fields is ugly.

Use the button to toggle the layout from desktop ("left-label") to mobile ("top-label").
Use the button to stretch the form to full width.

HTML Form Layout Example
 

Notice that required field labels are also bold for field-sets, in case the set contains at least one required field. Example is the "More Text" group. On the other hand there is no required field in the "Date / Time" group, thus its label is not bold.

Core Form Layout CSS

I will present this in small doses. You can find the entire source code of the example on bottom of the article.

Most important to know is that I used line-height to get rid of vertical alignment problems (still open problems!), and box-sizing: border-box; to stop fields hanging out at right side.

About CSS coding:
I recommend to write comments on any CSS line, at least one per rule-set. Only this keeps CSS code maintainable! Remember that a rule like position: relative; can serve several purposes, so we need to make explicit why we apply it.

Basic Label Styling

      /* Smaller sans-serif font. */
form label
{
font-size: 76%;
font-family: sans-serif;
}

/* Add colon after any label. */
form label::after
{
content: ":";
}
/* But not on label after radio. */
form input[type = 'radio'] + label::after
{
content: "";
}

The label should have a smaller font than the field. This also will uncover vertical alignment problems in the layout.
Further this CSS sets a colon after the label, and avoids it for radio buttons where the label is right of the button.

Labels of Required Fields

The JavaScript I introduced in my recent Blog copies the attribute required from field to label, the CSS below relies on that.

      /* Set asterisk before required fields. */
form label[required]::before
{
content: "* ";
}

/* Make labels for required fields better visible. */
form label[required]
{
font-weight: bold;
}

This is for setting an asterisk (*) before any label of a required field, and displaying it in a bold font.

DIV Table Layout

      form .table
{
display: table;
width: 100%; /* if parent is 100%, go with it */
}

form .table > div
{
display: table-row;
line-height: 2em; /* needed for vertical line-alignment */
}

This defines the table-layout inside the form, not including the "Submit" and "Reset" buttons. It will always fill its parent's width fully, so you should wrap it into either a display: inline-block; (natural width) or a display: block; (full width) DIV container.

The table-row receives its line-height here, important to avoid vertical alignment problems. The table-cell is not yet defined, it will be set specifically later for either mobile or desktop.

Layout of Fields Inside Tables

      /* Stretch fields to full cell width, except checkboxes and radios. */
form .table > div > input:not([type = 'radio']):not([type = 'checkbox']),
form .table > div > textarea,
form .table > div > select
{
width: 100%;
}

/* Avoid text fields hanging out at right due to content-box sizing. */
form .table input,
form .table textarea,
form .table select
{
box-sizing: border-box;
}

/* Let the user resize big fields vertically. */
form .table select[multiple],
form .table textarea
{
resize: vertical;
}

Fields should fill their cell's full width, not keep their "natural" width which is browser-specific.
Force the browser to calculate their border-box, not content-box, else they will hang out at right side.
Optionally we should allow the user to resize choosers that may contain lots of rows, like <textarea> and <select multiple>.

Left Label for Desktop

      form .left-label > div > label,
form .left-label > div > input,
form .left-label > div > select,
form .left-label > div > textarea,
form .left-label > div > div,
form .left-label > div > fieldset
{
display: table-cell; /* display elements horizontally */
vertical-align: middle; /* avoid vertical alignment problems */

margin-top: 0.2em; /* vertical line distance */
margin-bottom: 0.2em;
}

form .table.left-label > div label
{
text-align: right;
padding-right: 0.2em; /* distance to right field */

vertical-align: top; /* necessary for labels of nested fieldsets */
}

So here is a list of element names that can be inside a table-cell. For a desktop-suited table with two columns, all these elements should behave as table-cell. We allow beside input, select and textarea also fieldset and div elements.
Their vertical alignment should be "middle" by default.
To create a little space between layout rows there is margin at bottom.

Labels should be aligned right in left-label variant, to be as near as possible to the field, but nevertheless keep a little padding-distance.
For labels we overwrite the default vertical alignment with "top" here, because in case a whole fieldset (high) is on right side, we want the label to stay in a visible range.


Mind that there are no further rules for the top-label layout variant. As any input field has been stretched to 100%, its preceding label will automatically go to top. As a side-effect top-label will be the default, unless you put a CSS class="left-label" onto the DIV table root-element.


Optional Additions

Following introduces useful code to style initial validation, button bars and nested right-side containers (horizontal bars).

Visible Initial Validation

      form :not(output):not(fieldset):invalid /* fieldset would also be red */
{
box-shadow: 1px 1px 1px red;
}

If you want to make the validation markers already visible on document-load, add this rule-set. By default HTML forms would be validated by the browser only on a submit-event, and only then you would see the browser-made validation markers and tips.

Buttons and Toolbar

      form input[type = 'submit'],
form input[type = 'reset']
{
margin-top: 0.4em; /* space to form above */
font-size: 140%; /* using Unicode character as icon */
width: 33%; /* take a third of available space */
}

form input[type = 'submit']
{
color: green;
}
form input[type = 'reset']
{
color: red;
}

/* Variant label-top: put "Ok" to very right, "Cancel" will be at very left. */
form :not(.left-label) + .button-container input[type = 'submit']
{
float: right;
}

/* Variant label-left: align "Cancel" and "Ok" to middle. */
form .left-label + .button-container
{
text-align: center;
}

Try out of you like this appearance of buttons and their bar. It is different for top-label and left-label variants. Such things depend on ergonomics, current fashion, company-rules, and last not least customer wishes. The "Submit" button right now establishes slowly, but still buttons top or bottom is undecided.

Horizontal Layout

      .horizontal-bar  /* flex-direction row */
{
display: flex !important; /* else overwritten by table-cell! */
align-items: center; /* do not stretch vertically */
}

.horizontal-bar-natural /* natural size */
{
flex: initial;
}
.horizontal-bar-stretch /* takes all available space */
{
flex: auto;
}

This is a general purpose layout done through flexbox. Look at the "Date" - "Years Since" fields above for an example. It is a frequent case that you have several fields in a line, and one of them should take the most available space. Put a CSS class="horizontal-bar" onto the container DIV, and one of class="horizontal-bar-natural" (just once!) or class="horizontal-bar-stretch" onto the elements in row.

General Purpose CSS

      /* Enable a fluid responsive display of forms and fieldsets. */
div.responsive
{
display: inline-block; /* take just the space needed */
vertical-align: top; /* align to top if any peer DIV is present */
}

/* Keep label and radio-button always on same layout row. */
.sameline
{
white-space: nowrap;
}

/** Round border for fieldset. */
fieldset
{
border-radius: 0.5em;
}

If you want DIV containers to arrange themselves responsively side-by-side, you can set a CSS class="responsive" into it.

The CSS class="sameline" is necessary to tie radio buttons to their label in a way that never the label is in a different layout row than the button. This could be quite misleading! Look at this example:

The same when <span class="sameline"> was wrapped around label and input:


Entire Source Code

Press the arrow-button to see HTML and CSS source code of this example.

Click to see example source.

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<!DOCTYPE HTML>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1"/>

<title>HTML Form Test</title>

<!-- Core form layout -->

<style> /** Style labels of fields. */

/* Smaller sans-serif font. */
form label
{
font-size: 76%;
font-family: sans-serif;
}

/* Add colon after any label. */
form label::after
{
content: ":";
}
/* But not on label after radio. */
form input[type = 'radio'] + label::after
{
content: "";
}
</style>

<style> /** Style labels of required fields. */

/* Set asterisk before required fields. */
form label[required]::before
{
content: "* ";
}

/* Make labels for required fields better visible. */
form label[required]
{
font-weight: bold;
}
</style>

<style> /** DIV table layout. */

form .table
{
display: table;
width: 100%; /* if parent is 100%, go with it */
}

form .table > div
{
display: table-row;
line-height: 2em; /* needed for vertical line-alignment */
}
</style>

<style> /** Layout fields inside tables. */

/* Stretch fields to full cell width, except checkboxes and radios. */
form .table > div > input:not([type = 'radio']):not([type = 'checkbox']),
form .table > div > textarea,
form .table > div > select
{
width: 100%;
}

/* Avoid text fields hanging out at right due to content-box sizing. */
form .table input,
form .table textarea,
form .table select
{
box-sizing: border-box;
}

/* Let the user resize big fields vertically. */
form .table select[multiple],
form .table textarea
{
resize: vertical;
}
</style>

<style> /** Layout for left-label variant */

form .left-label > div > label,
form .left-label > div > input,
form .left-label > div > select,
form .left-label > div > textarea,
form .left-label > div > div,
form .left-label > div > fieldset
{
display: table-cell; /* display elements horizontally */
vertical-align: middle; /* avoid vertical alignment problems */

margin-top: 0.2em; margin-bottom: 0.2em; /* vertical line distance */
}

form .table.left-label > div label
{
text-align: right;
padding-right: 0.2em; /* distance to right field */

vertical-align: top; /* necessary for labels of nested fieldsets */
}
</style>

<style> /* Layout for label-above variant. */
/*
* Because any input field has been stretched to 100%, the
* preceding label will automatically go to top. Nothing to do!
*/
</style>


<!-- Optional additions -->

<style> /** Make validation visible initially. */

form :not(output):not(fieldset):invalid /* fieldset would also be red */
{
box-shadow: 1px 1px 1px red;
}
</style>

<style> /* Button and toolbar styles. */

form input[type = 'submit'],
form input[type = 'reset']
{
margin-top: 0.4em; /* space to form above */
font-size: 140%; /* using Unicode character as icon */
width: 33%; /* take a third of available space */
}

form input[type = 'submit']
{
color: green;
}
form input[type = 'reset']
{
color: red;
}

/* Variant label-top: put "Ok" to very right, "Cancel" will be at very left. */
form :not(.left-label) + .button-container input[type = 'submit']
{
float: right;
}

/* Variant label-left: align "Cancel" and "Ok" to middle. */
form .left-label + .button-container
{
text-align: center;
}
</style>

<style> /** General purpose horizontal bar. */

.horizontal-bar /* flex-direction row */
{
display: flex !important; /* else overwritten by table-cell! */
align-items: center; /* do not stretch vertically */
}

.horizontal-bar-natural /* natural size */
{
flex: initial;
}
.horizontal-bar-stretch /* takes all available space */
{
flex: auto;
}
</style>

<style> /** General purpose layout styles. */

/* Enable a fluid responsive display of forms and fieldsets. */
div.responsive
{
display: inline-block; /* take just the space needed */
vertical-align: top; /* align to top if any peer DIV is present */
}

/* Keep label and radio-button always on same layout row. */
.sameline
{
white-space: nowrap;
}

/** Round border for fieldset. */
fieldset
{
border-radius: 0.5em;
}
</style>


<!-- Script to copy required and ids -->

<script>
/**
* Avoid duplication of "required" and "id" attributes in HTML forms.
* Any LABEL before an INPUT must get the INPUT's "id" value into its "for" attribute.
* Any LABEL before an INPUT must copy the INPUT's "required" if it exists.
* Sometimes the "required" attribute is not in the next element but in its sub-DOM.
*/
function manageIdAndRequired()
{
var count = 1; /* sequence number for unique ids */

/** Searches for "required" in given element and all sub-elements. */
function containsRequired(element) {
if (element.getAttribute("required") !== null)
return true;

var children = element.children;
for (var i = 0; i < children.length; i++)
if (containsRequired(children[i]))
return true;

return false;
}
/* end containsRequired() */

/** Copies the optional "required" attribute to LABEL, chains it with INPUT's id. */
function chainLabelToIdAndCopyRequired(label) {
var nextSibling = label.nextElementSibling;
var nextTagName = nextSibling ? nextSibling.tagName : undefined;

/* previous is just for radio-buttons */
var previousSibling = label.previousElementSibling;
var previousTagName = previousSibling ? previousSibling.tagName : undefined;
var isRadioLabel = (previousTagName === "INPUT");

if (isRadioLabel ||
nextTagName === "INPUT" ||
nextTagName === "SELECT" ||
nextTagName === "TEXTAREA" ||
nextTagName === "DIV" ||
nextTagName === "FIELDSET")
{
if ( ! isRadioLabel && containsRequired(nextSibling))
label.setAttribute("required", ""); /* copy attribute to non-radios */

if (label.getAttribute("for") === null) { /* chain id */
var sibling = isRadioLabel ? previousSibling : nextSibling;
var id = sibling.getAttribute("id");

if ( ! id && sibling.getAttribute("name")) { /* generate id from name */
var identity = "_"+count;
count++;
id = sibling.getAttribute("name")+identity;
sibling.setAttribute("id", id);
}

if (id)
label.setAttribute("for", id);
}
}
}
/* end chainLabelToIdAndCopyRequired() */

/* Iterate all forms on page */
var forms = document.getElementsByTagName("form");
for (var f = 0; f < forms.length; f++) {
var elementsInForm = forms[f].getElementsByTagName("*");
for (var i = 0; i < elementsInForm.length; i++) {
var element = elementsInForm[i];
if (element.tagName === "LABEL")
chainLabelToIdAndCopyRequired(element);
}
}
}

/* Execute function on page-load */
window.addEventListener("load", manageIdAndRequired);

</script>

</head>


<body>

<form>
<div class="responsive">
<fieldset>
<legend>HTML Form Layout Example</legend>

<div class="table">
<!-- <div class="table left-label"> -->

<div>
<label>Single Line</label>
<input name="single-line-text" type="text" required value="Default value in text-field">
</div>

<div>
<label>Password</label>
<input name="hidden-password" type="password" required>
</div>

<div>
<label>Number</label>
<input name="numeric" type="number" required>
</div>

<div>
<label>More Text</label>

<fieldset>
<div class="table left-label">

<div>
<label>E-Mail</label>
<input name="e-mail" type="email" required value="a@b.c">
</div>

<div>
<label>Telephone</label>
<input name="phone-number" type="tel" />
</div>

<div>
<label>URL</label>
<input name="url-address" type="url" value="protocol://host">
</div>

<div>
<label>Auto-Suggest</label>
<input list="browsers" name="auto-suggest"/>
<datalist id="browsers">
<option value="Firefox">
<option value="Chrome">
<option value="Opera">
<option value="Safari">
<option value="Edge">
</datalist>
</div>

<div>
<label>Search</label>
<input name="search-pattern" type="search">
</div>

<div>
<label>Multiple Lines</label>
<textarea name="multiline-text" required>Default
value
in
text
area</textarea>
</div>

</div> <!-- end table -->
</fieldset> <!-- end cell -->
</div> <!-- end row -->

<div>
<label>Date</label>
<div class="horizontal-bar">
<script>
function calculateYearsSince(date) {
var millis = Date.now() - new Date(date).getTime();
var years = millis / 1000 / 60 / 60 / 24 / 365;
var age = (years > 0) ? Math.floor(years) : Math.ceil(years);
document.getElementById("yearsSince").value = age;
}
</script>
<input class="horizontal-bar-stretch" name="day-only" type="date" required oninput="calculateYearsSince(this.value);">
&nbsp;
<label class="horizontal-bar-natural" for="yearsSince">Years Since</label>
<output name="yearsSince" id="yearsSince"></output>
</div>
</div>

<div>
<label>Date / Time</label>

<fieldset>
<div class="table left-label">

<div>
<label>Time</label>
<input name="time-only" type="time">
</div>

<div>
<label>Date / Time Local</label>
<input name="date-and-time-local" type="datetime-local">
</div>

<div>
<label>Month</label>
<input name="month-only" type="month">
</div>

<div>
<label>Week</label>
<input name="week-only" type="week">
</div>

</div> <!-- end table -->
</fieldset> <!-- end cell -->
</div> <!-- end row -->

<div>
<label>Other Inputs</label>

<fieldset>
<div class="table left-label">

<div>
<label>Radiobuttons</label>
<div>
<!-- span.sameline: don't let the label and the button separate to different layout rows -->
<span class="sameline"><input name="gender" type="radio" value="male" required><label>Male</label></span>
<span class="sameline"><input name="gender" type="radio" value="female" required><label>Female</label></span>
<span class="sameline"><input name="gender" type="radio" value="other" required><label>Other</label></span>
</div>
</div>

<div>
<label>More Radiobuttons</label>
<div>
<!-- div: display each radio-button on a new layout row -->
<div><input name="RGB" type="radio" value="red" ><label>Red</label></div>
<div><input name="RGB" type="radio" value="green"><label>Green</label></div>
<div><input name="RGB" type="radio" value="blue" ><label>Blue</label></div>
</div>
</div>

<div>
<label>Single Select</label>
<select name="single-select" required>
<optgroup label="Compiled">
<option value="java">Java</option>
<option value="c++">C++</option>
</optgroup>
<optgroup label="Interpreted">
<option value="es6">EcmaScript</option>
<option value="python">Python</option>
</optgroup>
</select>
</div>

<div>
<label>Multiple Select</label>
<select name="multi-select" multiple required>
<option value="one">Use</option>
<option value="two">Shift</option>
<option value="three">and</option>
<option value="four">Control</option>
<option value="five">Keys</option>
<option value="six">with</option>
<option value="seven">Mouse</option>
</select>
</div>

<div>
<label>Range</label>
<input name="slider" type="range">
</div>

<div>
<label>Color</label>
<input name="colour" type="color">
</div>

<div>
<label>File</label>
<input name="file-upload" type="file">
</div>

</div> <!-- end table -->
</fieldset> <!-- end cell -->
</div> <!-- end row -->

<div>
<label>License Read</label>
<input name="boolean" type="checkbox" required>
</div>

</div> <!-- end table -->


<div class="button-container">
<input title="Reset" type="reset" value="&#x2718;">
<input title="Submit" type="submit" value="&#x2714;">
</div>


</fieldset> <!-- end top fieldset -->
</div> <!-- end div.responsive -->

</form>

</body>
</html>




ɔ⃝ Fritz Ritzberger, 2019-01-01