correct 508 issues on site docs (#194)

## Description
Making small CSS changes to account for 508 issues
[axe](https://www.deque.com/axe/) flagged on the site docs. Note: this
does not account for any issues on the API docs.

## Notes
The syntax highlighting in the code blocks can cause readability issues
due to poor contrast. One way to correct for this is to remove the
syntax highlighting (just mark every code block as plaintext).

docs/mkdocs.yml

@@ -3,9 +3,10 @@ theme:
   name: "material"
   icon:
     repo: fontawesome/brands/github
+extra_css:
+  - stylesheets/custom.css
 plugins:
   - mermaid2
-  - offline
 markdown_extensions:
   - def_list
   - pymdownx.highlight:

docs/site/installation.md

@@ -19,14 +19,14 @@ This guide provides two installation paths:
 
     Pull the pre-built image from the GitHub Container Registry
 
-    ```bash
+    ```
     docker pull ghcr.io/cdcgov/recordlinker:latest
     ```
     
 1. **Run the Docker Container**
     Launch the container with any necessary environment variables.  Only the `DB_URI` environment variable is required.
 
-    ```bash
+    ```
     docker run -d -e DB_URI=postgresql+psycopg2://postgres:pw@localhost:5432/postgres -p 8000:8000 ghcr.io/cdcgov/recordlinker:latest
     ```
 
@@ -48,30 +48,30 @@ This guide provides two installation paths:
 1. **Clone the Repository**
     Clone the repository to your local machine:
 
-    ```bash
+    ```
     git clone https://github.com/CDCgov/RecordLinker.git
     cd RecordLinker
     ```
 
 1. **Set up a Virtual Environment**
     Create and activate a virtual environment (recommended for isolating dependencies):
 
-    ```bash
+    ```
     python -m venv venv
     source venv/bin/activate  # On Windows, use `venv\Scripts\activate`
     ```
 
 1. **Install Dependencies**
     Install the necessary dependencies from requirements.txt:
 
-    ```bash
+    ```
     pip install '.[dev]' # For production dependencies, use `pip install .[prod]`
     ```
 
 1. **Optional: Set Environment Variables**
     Configure environment variables by editing the default .env file in the project root or exporting them directly in your terminal:
 
-    ```bash
+    ```
     export DB_URI=sqlite:///db.sqlite3
     export CONNECTION_POOL_SIZE=20
     ```
@@ -81,7 +81,7 @@ This guide provides two installation paths:
 1. **Run the Application**
 Start the application with the following command:
 
-    ```bash
+    ```
     uvicorn recordlinker.main:app
     ```
 

docs/site/stylesheets/custom.css

@@ -0,0 +1,8 @@
+/* 508: Underline all hyperlinks */
+a {
+    text-decoration: underline;
+}
+/* 508: Change the color of footer text for contrast */
+.md-copyright {
+    color:var(--md-footer-fg-color);
+}