# Styling with GeoNode (Basics)
This section introduces the concepts of the **Styled Layer Descriptor** (`SLD`) markup language.
`SLD` is the styling engine used by the GIS backend (i.e. GeoServer). It allows us to create beautiful and informative portrayals out of raw geospatial data.
In this section, you will also use the `CSS` [extension module](http://docs.geoserver.org/latest/en/user/styling/css/index.html) that allows you to build map styles using a compact, expressive styling language already well known to most web developers: **Cascading Style Sheets**.
The standard `CSS` language has been extended to allow for map filtering and managing all the details of producing a map.
The examples will have styles in `SLD` and `CSS` languages.
**WARNING**: `CSS` styling is only supported by GeoServer, which is the default GIS backend provided with GeoNode. In the [official GeoServer Styling documentation](http://docs.geoserver.org/latest/en/user/styling/index.html#styling), you can find useful references, such as the [SLD Cookbook](http://docs.geoserver.org/latest/en/user/styling/sld/cookbook/index.html) and the [CSS Cookbook](http://docs.geoserver.org/latest/en/user/styling/css/cookbook/index.html).
## Uploading and Replacing the Dataset Default Style
This procedure allows us to quickly update and replace the current dataset default style with a new one from the hard disk.
**WARNING**: This procedure currently only works with `SLD` files
- Before using the style, we will need to slightly modify it to match the correct field names of the `Mainrd` dataset.
- Go to the `Mainrd` dataset detail page;
- Click on 1.the system `File Browser`, navigate to 2.`/opt/data/sample_data/user_data`
* `RIGHT-CLICK` with the mouse on the file named `foss4g_mainrd.sld`
* Select and click 3.`Open with Other Application`
- Click on the `View all applications` button and then select `Text Editor` and change the 1.`label_name` to uppercase `LABEL_NAME`, click 2.`Save`, and 3.`close`
- Go to the `Mainrd` dataset detail page; click on 1.`Edit` -> 2.`Upload Style`
- From the `Style Upload` page, click on the `Choose files` button and navigate to 1.`/opt/data/sample_data/user_data`. Select the file 2.`foss4g_mainrd.sld` and then click on 3.`Open`
- Click on `Upload file` and, once finished, on `Return to Dataset`
**WARNING**: If the page does not refresh correctly, click together `CTRL-SHIFT-CANC` and clear the browser image cache from the last hour
- Go back to the dataset detail page and refresh the page. Notice how the `Legend` has changed, as has the styling of the dataset. Try zooming in, you will notice some labels appearing.
- Go ahead and update the `Thumbnail` by clicking on the `Edit` -> `Edit Info`. You can then update it in two ways:
1: click on the upload icon on the current thumbnail and upload an image from your device.
2: click on the map icon and adjust the map to the desired dimensions.
- Once the thumbnail has been saved
- Go back to the datasets list and verify it has been updated
## Adding more Base Datasets and Styles
### Boulder City Limits
- From the location `/opt/data/sample_data/pretty_maps/data/boulder` upload the dataset `BoulderCityLimits`
- From the location `/opt/data/sample_data/pretty_maps/styles` upload the style `foss4g_citylimits.sld`
- The dataset and legend should appear as shown here
- Set the thumbnail as we have done previously
### Buildings
- From the location `/opt/data/sample_data/pretty_maps/data/boulder` upload the dataset `Buildings050714`
- **WARNING**: pay attention to only select the files shown in the figure below, do not include the `.sld` and `.xml` ones
- From the location `/opt/data/sample_data/pretty_maps/styles` upload the style `foss4g_buildings.sld`
- Notice that the Legend presents 3 different symbols, also notice that no feature will be visible unless you zoom very close to the buildings
- By taking a closer look at the style source code, we can see that:
* We have a set of `Rule` elements, each one constrained by some `ScaleDenominator` limits.
* The `Shadow` rule also defines a `Displacement` making the polygons translate on the `X-Y` dataset
```xml
Buildings050714
1
Shadow
5000.0
15000.0
the_geom
6.0
-6.0
Label
10000.0
#FF0000
LABEL_NAME
Arial
12.0
normal
normal
0.5
0.5
0.0
0.0
0.0
2
#FFFFFF
#000000
100
50
fill
25000.0
#B3B3B3
```
- Set the thumbnail as we have done previously
### Parcels
- From the location `/opt/data/sample_data/pretty_maps/data/boulder` upload the dataset `Parcels`
- 
- From the location `/opt/data/sample_data/pretty_maps/styles` upload the style `foss4g_parcels.sld`. The dataset only appears at very high levels of zoom
- 
- Set the thumbnail as we have done previously
### Pointlm
- From the location `/opt/data/sample_data/pretty_maps/data/boulder` upload the dataset `pointlm`
- From the location `/opt/data/sample_data/pretty_maps/styles` upload the style `foss4g_point_landmark_ds_ns.sld`
- At a first glance, the dataset will appear as a set of grey square points. Let's take a closer look at the `SLD` definition
```xml
tl 2010 08013 pointlm
landmarks
IMAGE
0
image/png
true
FULLNAME
Arial
12.0
normal
normal
0.5
1.0
0.0
-14.0
0.0
1.5
#FFFFFF
#000033
200000
100
```
We can see the notation `xlink:href="./img/landmarks/${IMAGE}"`, this is a GeoServer extension allowing us to read some values from the source dataset attributes and then use them to dynamically render the `SLD`.
In that specific case, GeoServer looks for some filenames according to the `${IMAGE}` attribute value in a relative folder named `./img/landmarks/`.
To correctly render this style, we will need to copy this folder, containing the correctly named images, into the GeoServer `styles` folder.
We will also have to give that folder the correct permissions to allow GeoServer to access it.
- The first step is to copy the `img` folder into the correct GeoServer `styles` one
* Open a `system file browser` window and go to 1.`/opt/data/sample_data/pretty_maps/styles`
* `RIGHT-CLICK` on the 2.`img` folder
* Select 3.`Copy` from the side menu
- From the `system file browser` window go to `/opt/data/geoserver_data/workspaces/geonode/`, it will probably ask for `ROOT` permissions. Just insert the password `geonode` every time it asks for one
- Go to the styles folder inside the GeoNode workspace and hit `CTRL+V`, this will copy the `img` folder into the new location
- `RIGHT-CLICK` on the newly created 2.`img` folder and click on the 3.`Properties` link of the context menu
- Assign the permissions to the `others group` as shown in the figure below
- Refresh the dataset page, you should be able to see the icons appearing on the map preview
- Set the thumbnail as we have done previously
### Remaining Boulders datasets
- From the location `/opt/data/sample_data/pretty_maps/data/boulder` upload the datasets:
* `srtm_boulder`
* `Streets`
* `Trails`
* `Wetlands_regulatory_area`
- From the location `/opt/data/sample_data/pretty_maps/styles` upload the styles:
* `foss4g_dem2.sld` to `srtm_boulder`
* `foss4g_streets.sld` to `Streets`
* `foss4g_trails.sld` to `Trails`
* `foss4g_wetlands.sld` to `Wetlands_regulatory_area`
#### [Next Section: Pretty Maps with GeoNode](MAPPING_GEONODE.md)