html-Programmierung von Tabellen

[HaWe]

hallo,
ich versuche mich gerade in einer html-Programmierung von Tabellen.
es sollte so hübsch aussehen wie hier:

https://wiki.selfhtml.org/wiki/HTML/..._einer_Tabelle

ich habe es mal mit Beispielwerten versucht, aber ich bekomme keine eingerahmten Tabellenfelder, lediglich die Tabs stimmen:

QUELLE 
°C inn 	rF % 	T min 	T max 	°C ext 	- 	T min 	T max
10.1 	88 	-1 	18 	8.8 	- 	-2.2 	10.1
0 	11 	22 	33 	44 	- 	- 	-
espA0 	Erde1 	Erde2 	muxA2 	muxA3 	- 	- 	-

der Test-Sourcecode sieht z.Zt so aus (für ESP8266 nodeMCU):

     script+= "<table> ";

     script+= "   <caption>QUELLE</caption> ";

     script+= "    <thead> ";
     script+= "      <tr> ";
     script+= "        <th>°C inn</th> ";
     script+= "        <th>rF %</th> ";
     script+= "        <th>T min</th> ";
     script+= "        <th>T max</th> ";
     script+= "        <th>°C ext</th> ";
     script+= "        <th> - </th> ";
     script+= "        <th>T min</th> ";
     script+= "        <th>T max</th> ";
     script+= "      </tr> ";
     script+= "    </thead> ";
 
     script+= "    <tbody> ";
     script+= "      <tr> ";
     script+= "        <th>10.1</th> ";
     script+= "        <th>88</th> ";
     script+= "        <th>-1</th> ";
     script+= "        <th>18</th> ";
     script+= "        <th>8.8</th> ";
     script+= "        <th> - </th> ";
     script+= "        <th>-2.2</th> ";
     script+= "        <th>10.1</th>   ";
     script+= "      </tr> ";

     script+= "      <tr> ";
     script+= "        <th>0</th> ";
     script+= "        <th>11</th> ";
     script+= "        <th>22</th> ";
     script+= "        <th>33</th> ";
     script+= "        <th>44</th> ";
     script+= "        <th> - </th> ";
     script+= "        <th> - </th> ";
     script+= "        <th> - </th> ";
     script+= "      </tr> ";
     
     script+= "    </tbody> ";
 
     script+= "    <tfoot> ";
     script+= "      <tr> ";
     script+= "        <th>espA0</th> ";
     script+= "        <th>Erde1</th> ";
     script+= "        <th>Erde2</th> ";
     script+= "        <th>muxA2</th> ";
     script+= "        <th>muxA3</th> ";
     script+= "        <th> - </th> ";
     script+= "        <th> - </th> ";
     script+= "        <th> - </th> ";
     script+= "      </tr> ";
     script+= "    </tfoot> ";
          

     script+= "  </table>  ";

was fehlt noch in meinem Code, um die Tabellen-Felder mit Rahmen und Farben hervor zu heben?