add anchor link to subheading in octoprint

input/projects/3d-printing/ctc-i3.md

 
 ## Heatbed Replacement
 
-
+The original FR-4 heatbed is very flimsy and bends easily.
+For this reason, I replaced it immediately with a very commonly available replacement heatbed made out of 3mm aluminium, with 214mm x 214mm.
+Below it I mounted some self-adhesive foam insulation.
 
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 ## MOSFET for Heatbed
 
-
+It is common knowledge that the heatbed MOSFETS on Anet A8 printers are not sufficient and present a fire hazard.
+Because my CTC-i3 has a different mainboard, I didn't think this problem applied to me.
+But sure enough, after a year or so of regular usage, the heatbed MOSFET, as well as some parts of the PCB of my mainboard stopped working and were visibly burnt.
+Because of this, I added the widely used beefy external MOSFET to power the heatbed.
 
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 So I simply got a properly sized piece of aluminium from ebay, drilled the holes for some small printed bearing holders and mounted the heatbed to it.
 This was easy and has worked very well as a replacement.
 
-TODO photos
+<!--%
+lightgallery([
+    [ "img/ctc_i3_bed.jpg", "Side view of printbed with insulation" ]
+])
+%-->
 
 ## Y-Axis Webcam Mount
 
 
 ## Power Button
 
-
+To use the power button with the Pi, see [my page about setting up OctoPrint](octoprint.html#power_button).
 
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input/projects/3d-printing/octoprint.md

 </pre>
 
 ## Physical Power Button
+<a class="anchor" name="power_button"></a>
 
 Besides controlling eg. an ATX power supply or a relay connecting the printer to the power supply, I also wanted a push-button connected to the Raspberry Pi that can toggle the power supply using the aforementioned connection on the Pi.
 This can be solved using a simple Python script.
 Of course, you may need to adjust the destination path on your webserver.
 Finally, add the script as a cronjob using `crontab -e`:
 
-    */5 * * * * sudo -u pi /home/pi/foto-script/upload.sh >/dev/null 2>/dev/null
+<pre class="sh_sh">
+*/5 * * * * sudo -u pi /home/pi/foto-script/upload.sh >/dev/null 2>/dev/null
+</pre>
 
 And that's it. An updated photo will appear on your webserver every 5 minutes.
 You can take a look at it [on my website](printer.html).

static/css/style.css

     #wrap {
         height: 5em;
     }
+
+    a.anchor {
+        display: block;
+        position: relative;
+        top: -175px;
+        visibility: hidden;
+    }
 }
 
 pre {