# Skinning the Fossil Web Interface
The Fossil web interface comes with a pre-configured look and feel. The default
look and feel works fine in many situations. However, you may want to change
the look and feel (the "skin") of Fossil to better suite your own individual tastes.
This document provides background information to aid you in that task.
## <a name="builtin"></a>Built-in Skins
Fossil comes with multiple built-in skins. If the default skin does not
suite your tastes, perhaps one of the other built-in skins will work better.
If nothing else, the built-in skins can serve as examples or baselines that
you can use to develop your own custom skin.
The sources to these built-ins can
be found in the Fossil source tree under the skins/ folder. The
[skins/](/dir?ci=trunk&name=skins)
folder contains a separate subfolder for each built-in skin, with each
subfolders holding at least these five files:
* css.txt
* details.txt
* footer.txt
* header.txt
* js.txt
Try out the built-in skins by using the --skin option on the
[fossil ui](/help?cmd=ui) or [fossil server](/help?cmd=server) commands.
## <a name="sharing"></a>Sharing Skins
The skin of a repository is not part of the versioned state and does not
"push" or "pull" like checked-in files. The skin is local to the
repository. However, skins can be shared between repositories using
the [fossil config](/help?cmd=configuration) command.
The "fossil config push skin" command will send the local skin to a remote
repository and the "fossil config pull skin" command will import a skin
from a remote repository. The "fossil config export skin FILENAME"
will export the skin for a repository into a file FILENAME. This file
can then be imported into a different repository using the
"fossil config import FILENAME" command. Unlike "push" and "pull",
the "export" and "import" commands are able to move skins between
repositories for different projects. So, for example, if you have a
group of related repositories, you can develop a skin for one of them,
then get a consistent look across all the repositories by exporting
the skin from the first repository and importing into all the others.
The file generated by "fossil config export" could be checked into
one of your repositories and versioned, if desired. This will not
automatically change the skin when looking backwards in time, but it
will provide an historical record of what the skin used to be and
allow the historical look of the repositories to be recreated if
necessary.
When cloning a repository, the skin of the new repository is initialized to
the skin of the repository from which it was cloned.
# Structure Of A Fossil Web Page
Every HTML page generated by Fossil has the same basic structure:
<blockquote><table border=1 cellpadding=10><tbody>
<tr><td style='background-color:lightgreen;text-align:center;'>
Fossil-Generated HTML Header</td></tr>
<tr><td style='background-color:lightblue;text-align:center;'>Content Header</td></tr>
<tr><td style='background-color:lightgreen;text-align:center;'>
Fossil-Generated Content</td></tr>
<tr><td style='background-color:lightblue;text-align:center;'>Content Footer</td></tr>
<tr><td style='background-color:lightgreen;text-align:center;'>
Fossil-Generated HTML Footer</td></tr>
</tbody></table></blockquote>
The green parts are *usually* generated by Fossil. The blue parts
are things that you, the administrator, get to modify in order to
customize the skin.
Fossil *usually* (but not always - [see below](#override))
generates the initial HTML Header section of a page. The
generated HTML Header will look something like this:
<html>
<head>
<base href="..." />
<meta http-equiv="Content-Security-Policy" content="...." />
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>....</title>
<link rel="stylesheet" href="..." type="text/css" />
</head>
<body>
In most cases, it is best to leave the Fossil-generated HTML Header
alone. (One exception is when the administrator needs to include links
to additional CSS files.) The configurable part of the skin begins
with the Content Header section which should follow this template:
<div class="header">
... top banner and menu bar ...
</div>
Note that `<div class="header">` and `</div>` tags must be included in
the Content Header text of the skin. In other words, you, the
administrator, need to supply that text as part of your skin
customization.
The Fossil-generated Content section immediately follows the Content Header.
The Content section will looks like this:
<div class="content">
... Fossil-generated content here ...
</div>
After the Content is the custom Content Footer section which should
follow this template:
<div class="footer">
... skin-specific stuff here ...
</div>
<script nonce="$nonce">
<th1>styleScript</th1>
</script>
As with the Content Header, the template elements of the Content Footer
should appear exactly as they are shown.
Finally, Fossil always adds its own footer (unless overridden)
to close out the generated HTML:
</body>
</html>
## <a name="override"></a>Overriding the HTML Header and Footer
Notice that the `<html>`, `<head>`, and opening `<body>`
elements at the beginning of the document,
and the closing `</body>` and `</html>` elements at the end are automatically
generated by Fossil. This is recommended.
However, for maximum design flexibility, Fossil allows those elements to be
supplied as part of the configurable Content Header and Content Footer.
If the Content Header contains the text "`<body`", then Fossil assumes that
the Content Header and Content Footer will handle all of the `<html>`,
`<head>`, and `<body>` text itself, and the Fossil-generated header and
footer will be blank.
When overriding the HTML Header in this way, you will probably want to use some
of the [TH1 variables documented below](#vars) such as `$stylesheet_url`
to avoid hand-writing code that Fossil can generate for you.
# Designing, Debugging, and Installing A Custom Skin
It is possible to develop a new skin from scratch. But a better and easier
approach is to use one of the existing built-in skins as a baseline and
make incremental modifications, testing after each step, to obtain the
desired result.
The skin is controlled by five files:
<blockquote><dl>
<dt><b>css.txt</b></dt><dd>
<p>The css.txt file is the text of the CSS for Fossil.
Fossil might add additional CSS elements after the
the css.txt file, if it sees that the css.txt omits some
CSS components that Fossil needs. But for the most part,
the content of the css.txt is the CSS for the page.</dd>
<dt><b>details.txt</b><dt><dd>
<p>The details.txt file is short list of settings that control
the look and feel, mostly of the timeline. The default
details.txt file looks like this:
<blockquote><pre>
timeline-arrowheads: 1
timeline-circle-nodes: 1
timeline-color-graph-lines: 1
white-foreground: 0
</pre></blockquote>
The first three setings in details.txt control the appearance
of certain aspects of the timeline graph. The number on the
right is a boolean - "1" to activate the feature and "0" to
disable it. The "white-foreground:" setting should be set to
"1" if the page color has light-color text on a darker background,
and "0" if the page has dark text on a light-colored background.</dd>
<dt><b>footer.txt</b> and <b>header.txt</b></dt><dd>
<p>The footer.txt and header.txt files contain the Content Footer
and Content Header respectively. Of these, the Content Header is
the most important, as it contains the markup used to generate
the banner and menu bar for each page.
<p>Both the footer.txt and header.txt file are
[processed using TH1](#headfoot) prior to being output as
part of the overall web page.</dd>
<dt><b>js.txt</b></dt><dd>
<p>The js.txt file is intended to be javascript. The complete
text of this javascript is typically inserted into the Content Footer
by this part of the "footer.txt" file:
<blockquote><pre>
<script nonce="$nonce">
<th1>styleScript</th1>
</script>
</pre></blockquote>
<p>The js.txt file was originally intended to insert javascript
that controls the hamburger menu.
The footer.txt file probably should contain lines like the
above, even if js.txt is empty.</dd>
</dl></blockquote>
Developing a new skin is simply a matter of creating appropriate
versions of these five control files.
### Skin Development Using The Web Interface
Users with admin privileges can use the Admin/Skin configuration page
on the web interface to develop a new skin. The development of a new
skin occurs without disrupting the existing skin. So you can work on
a new skin for a Fossil instance while the existing skin is still in
active use.
The new skin is a "draft" skin. You initialize one of 9 draft skins
to either the current skin or to one of the built-in skins. Then
use forms to edit the 5 control files described above. The new
skin can be tested after each edit. Finally, once the new skin is
working as desired, the draft skin is "published" and becomes the
new live skin that most users see.
### Skin Development Using A Local Text Editor
An alternative approach is to copy the five control files for your
baseline skin into a temporary working directory (here called
"./newskin") and then launch the [fossil ui](/help?cmd=ui) command
with the "--skin ./newskin" option. If the argument to the --skin
option contains a "/" character, then the five control files are
read out of the directory named. You can then edit the control
files in the ./newskin folder using you favorite text editor, and
press "Reload" on your browser to see the effects.
## <a name="headfoot"></a>Header and Footer Processing
The `header.txt` and `footer.txt` control files of a skin are the HTML text
of the Contnet Header and Content Footer, except that before being inserted
into the output stream, the text is run through a
[TH1 interpreter](./th1.md) that might adjust the text as follows:
* All text within <th1>...</th1> is omitted from the
output and is instead run as a TH1 script. That TH1
script has the opportunity to insert new text in place of itself,
or to inhibit or enable the output of subsequent text.
* Text of the form "$NAME" or "$<NAME>" is replaced with
the value of the TH1 variable NAME.
For example, first few lines of a typical Content Header will look
like this:
<div class="header">
<div class="title"><h1>$<project_name></h1>$<title>/div>
After variables are substituted by TH1, that will look more like this:
<div class="header">
<div class="title"><h1>Project Name</h1>Page Title</div>
As you can see, two TH1 variable substitutions were done.
The same TH1 interpreter is used for both the header and the footer
and for all scripts contained within them both. Hence, any global
TH1 variables that are set by the header are available to the footer.
## <a name="menu"></a>Customizing the ≡ Hamburger Menu
The menu bar of the default skin has an entry to open a drop-down menu with
additional navigation links, represented by the ≡ button (hence the name
"hamburger menu"). The Javascript logic to open and close the hamburger menu
when the button is clicked is contained in the optional Javascript part (js.txt)
of the default skin. Out of the box, the drop-down menu shows the [Site
Map](../../../sitemap), loaded by an AJAX request prior to the first display.
The ≡ button for the hamburger menu is added to the menu bar by the following
TH1 command in the default skin header.txt, right before the menu bar links:
html "<a id='hbbtn' href='#'>☰</a>"
The hamburger button can be repositioned between the other menu links (but the
drop-down menu is always left-aligned with the menu bar), or it can be removed
by deleting the above statement (the Javascript logic detects this case and
remains idle, so it's not necessary to modify the default skin js.txt).
The following empty element at the bottom of the default skin header.txt serves
as the panel to hold the drop-down menu elements:
<div id='hbdrop'></div>
Out of the box, the contents of the panel is populated with the [Site
Map](../../../sitemap), but only if the panel does not already contain any HTML
elements (that is, not just comments, plain text or non-presentational white
space). So the hamburger menu can be customized by replacing the empty `<div
id='hbdrop'></div>` element with a menu structure knitted according to the
following template:
<div id="hbdrop" data-anim-ms="400">
<ul class="columns" style="column-width: 20em; column-count: auto">
<!-- NEW GROUP WITH HEADING LINK -->
<li>
<a href="$home$index_page">Link: Home</a>
<ul>
<li><a href="$home/timeline">Link: Timeline</a></li>
<li><a href="$home/dir?ci=tip">Link: File List</a></li>
</ul>
</li>
<!-- NEW GROUP WITH HEADING TEXT -->
<li>
Heading Text
<ul>
<li><a href="$home/doc/trunk/www/customskin.md">Link: Theming</a></li>
<li><a href="$home/doc/trunk/www/th1.md">Link: TH1 Scripts</a></li>
</ul>
</li>
<!-- NEXT GROUP GOES HERE -->
</ul>
</div>
The custom `data-anim-ms` attribute can be added to the panel element to direct
the Javascript logic to override the default menu animation duration of 400 ms.
A faster animation duration of 80-200 ms may be preferred for smaller menus. The
animation is disabled by setting the attribute to `"0"`.
## <a name="vars"></a>TH1 Variables
Before expanding the TH1 within the header and footer, Fossil first
initializes a number of TH1 variables to values that depend on
repository settings and the specific page being generated.
* **project_name** - The project_name variable is filled with the
name of the project as configured under the Admin/Configuration
menu.
* **project_description** - The project_description variable is
filled with the description of the project as configured under
the Admin/Configuration menu.
* **title** - The title variable holds the title of the page being
generated.
The title variable is special in that it is deleted after
the header script runs and before the footer script. This is
necessary to avoid a conflict with a variable by the same name used
in my ticket-screen scripts.
* **baseurl** - The root of the URL namespace for this server.
* **secureurl** - The same as $baseurl except that if the scheme is
"http:" it is changed to "https:"
* **home** - The $baseurl without the scheme and hostname. For example,
if the $baseurl is "http://projectX.com/cgi-bin/fossil" then the
$home will be just "/cgi-bin/fossil".
* **index_page** - The landing page URI as
specified by the Admin/Configuration setup page.
* **current_page** - The name of the page currently being processed,
without the leading "/" and without query parameters.
Examples: "timeline", "doc/trunk/README.txt", "wiki".
* **csrf_token** - A token used to prevent cross-site request forgery.
* **default_csp** - [Fossil’s default CSP](./defcsp.md) unless
[overridden by custom TH1 code](./defcsp.md#th1). Useful within
the skin for inserting the CSP into a `<meta>` tag within [a
custom `<head>` element](#headfoot).
* **nonce** - The value of the cryptographic nonce for the request
being processed.
* **release_version** - The release version of Fossil. Ex: "1.31"
* **manifest_version** - A prefix on the check-in hash of the
specific version of fossil that is running. Ex: "\[47bb6432a1\]"
* **manifest_date** - The date of the source-code check-in for the
version of fossil that is running.
* **compiler_name** - The name and version of the compiler used to
build the fossil executable.
* **login** - This variable only exists if the user has logged in.
The value is the username of the user.
* **stylesheet_url** - A URL for the internal style-sheet maintained
by Fossil.
* **log\_image\_url** - A URL for the logo image for this project, as
configured on the Admin/Logo page.
* **background\_image\_url** - A URL for a background image for this
project, as configured on the Admin/Logo page.
All of the above are variables in the sense that either the header or the
footer is free to change or erase them. But they should probably be treated
as constants. New predefined values are likely to be added in future
releases of Fossil.
## <a name="procedure"></a>Suggested Skin Customization Procedure
Developers are free, of course, to develop new skins using any method they
want, but the following is a technique that has worked well in the past and
can serve as a starting point for future work:
1. Select a built-in skin that is closest to the desired look. Make
copies of the css, footer, and header into files name "css.txt",
"details.txt",
"footer.txt", and "header.txt" in some temporary directory.
If the Fossil source code is available, then these three files can
be copied directly out of one of the subdirectories under skins. If
sources are not easily at hand, then a copy/paste out of the
CSS, footer, and header editing screens under the Admin menu will
work just as well. The important point is that the three files
be named exactly "css.txt", "footer.txt", and "header.txt" and that
they all be in the same directory.
2. Run the [fossil ui](../../../help?cmd=ui) command with an extra
option "--skin SKINDIR" where SKINDIR is the name of the directory
in which the three txt files were stored in step 1. This will bring
up the Fossil website using the tree files in SKINDIR.
3. Edit the four txt files in SKINDIR. After making each small change,
press Reload on the web browser to see the effect of that change.
Iterate until the desired look is achieved.
4. Copy/paste the resulting css.txt, details.txt,
header.txt, and footer.txt files
into the CSS, details, header, and footer configuration screens
under the Admin/Skins menu.
## See Also
* [Customizing the Timeline Graph](customgraph.md)