tweak docs

docs/book.toml

 src = "src"
 
 [output.html]
+default-theme = "rust"
+preferred-dark-theme = "ayu"
 git-repository-url = "https://github.com/drinkrobotics/dispensy"
 edit-url-template = "https://github.com/drinkrobotics/dispensy/edit/main/docs/{path}"
+site-url = "/dispensy/"

docs/generate_docs.sh

     name=`echo $f | sed 's:src/plot/dispensy_sch.svg/::g' | sed 's:.svg::g'`
     echo $name
     echo "<h2>$name</h2>" >> src/inc_dispensy_sch.md
-    echo "<div style=\"background-color: white;\">" >> src/inc_dispensy_sch.md
+    echo "<div style=\"background-color: white; border: 1px solid black;\">" >> src/inc_dispensy_sch.md
     echo "<embed type=\"image/svg+xml\" src=\"$file\" id=\"pz_$name\" style=\"width:100%;\"/>" >> src/inc_dispensy_sch.md
     echo "<script>" >> src/inc_dispensy_sch.md
     echo "document.getElementById('pz_$name').addEventListener('load', function(){" >> src/inc_dispensy_sch.md

docs/src/main_board_pcb.md

 ## 2D PCB Layout
 
 <script src="js/svg-pan-zoom.js" charset="UTF-8"></script>
-<div style="background-color: white;">
+<div style="background-color: white; border: 1px solid black;">
     <embed type="image/svg+xml" src="./plot/dispensy_pcb.svg" id="pz_dispensy" style="width: 100%;"/>
     <script>
         document.getElementById('pz_dispensy').addEventListener('load', function(){
 ## 3D PCB Model
 
 <p>Status: "<span id="3d_info">Preparing 3D model...</span>"</p>
-<div id="3d_viewer" style="width: 100%; height: 100%;"></div>
+<div id="3d_viewer" style="width: 100%; height: 100%; background-color: white; border: 1px solid black;"></div>
 <script type="module">
     var view = document.getElementById('3d_viewer');
     view.style.height = (view.clientWidth * 0.707) + "px";