初めてNode-REDを使ってみよう、というかたのためのガイドです。
Node-REDを使ってシンプルなウェブサイトを作ってみます。

3.1. 画面を複数のdivに分割して使ってみます

Node-RED - フローをコピーする方法を参照し、下記のフローをコピペします。

[{"id":"88123141.6c60e","type":"template","z":"75eef29b.360a7c","name":"test14.html","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"<html>\n    <head>\n        <style type=\"text/css\">\n            {{{payload.css}}}\n        </style>\n    </head>\n    <body style=\"background-color: #EAE5E3\">\n        <div id='basic'>\n            <div id='a1'>\n                <h1>\n                    こんにちは。これはa1です。\n                </h1>\n            </div>\n            <div id='b1'>\n                これはb1です。\n            </div>\n            <div id='c1'>\n                これはc1です。\n            </div>\n        </div>\n    </body>\n</html>","x":470,"y":380,"wires":[["37d5c968.f7c61e"]]},{"id":"59cb5e42.620ad","type":"template","z":"75eef29b.360a7c","name":"css","field":"payload.css","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"#basic {\n  font-family: meiryo;\n}\n#a1 {\n  background-color:  #98d98e;\n  padding: 20px;\n  height: 100px;\n}\n#b1 {\n  background-color:  #e4de8a;\n  padding: 20px;\n  height: 100px;\n  text-align: center;\n  font-size: 18pt\n}\n#c1 {\n  background-color:  lightskyblue;\n  padding: 20px;\n  height: 100px;\n  text-align: left;\n  font-size: 18pt\n}\n","x":310,"y":380,"wires":[["88123141.6c60e"]]},{"id":"6edaaee3.af5ed","type":"http in","z":"75eef29b.360a7c","name":"","url":"/test14","method":"get","swaggerDoc":"","x":130,"y":380,"wires":[["59cb5e42.620ad"]]},{"id":"37d5c968.f7c61e","type":"http response","z":"75eef29b.360a7c","name":"","x":630,"y":380,"wires":[]},{"id":"b7f03bb4.58aeb8","type":"comment","z":"75eef29b.360a7c","name":"複数divを設定してみました","info":"","x":180,"y":340,"wires":[]}]

ブラウザでアプリ名/test14へアクセスし画面を確認します。
Node-REDでcssと書かれたテンプレートノード（オレンジ色）を開き、スタイルシートの内容を確認します。

test14.css

#basic {
  font-family: meiryo;
}
#a1 {
  background-color:  #98d98e;
  padding: 20px;
  height: 100px;
}
#b1 {
  background-color:  #e4de8a;
  padding: 20px;
  height: 100px;
  text-align: center;
  font-size: 18pt
}
#c1 {
  background-color:  lightskyblue;
  padding: 20px;
  height: 100px;
  text-align: left;
  font-size: 18pt
}

Node-REDでtest14.htmlと書かれたテンプレートノード（オレンジ色）を開き、htmlの内容を確認します。

test14.html

<html>
    <head>
        <style type="text/css">
            {{{payload.css}}}
        </style>
    </head>
    <body style="background-color: #EAE5E3">
        <div id='basic'>
            <div id='a1'>
                <h1>
                    こんにちは。これはa1です。
                </h1>
            </div>
            <div id='b1'>
                これはb1です。
            </div>
            <div id='c1'>
                これはc1です。
            </div>
        </div>
    </body>
</html>

div毎に色やフォント、文字の配置などを設定可能なことを確認します。

3.2.画面を横方向に分割する

下記はこのあとの写真を貼ってみるで使っているフローです。

画面を横方向に分割

[{"id":"4b8318b1.5544b8","type":"http in","z":"2302eb53.652cc4","name":"","url":"/test24","method":"get","swaggerDoc":"","x":90,"y":100,"wires":[["2d4b4493.1fe804"]]},{"id":"d9360f6e.c3bd2","type":"http response","z":"2302eb53.652cc4","name":"","x":710,"y":100,"wires":[]},{"id":"a5558d53.b42448","type":"comment","z":"2302eb53.652cc4","name":"写真を掲出します","info":"","x":110,"y":60,"wires":[]},{"id":"72030a24.31f77c","type":"template","z":"2302eb53.652cc4","name":"image","field":"payload.image","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"","x":390,"y":100,"wires":[["581c5a16.d8a26c"]]},{"id":"581c5a16.d8a26c","type":"template","z":"2302eb53.652cc4","name":"test24.html","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"<html>\n  <head>\n    <style type=\"text/css\">\n      {{{payload.css}}}\n    </style>\n  </head>\n  <body style=\"background-color: #EAE5E3; \">\n    <div id='basic'>\n        <div id='a1'><h1>写真を表示するサンプル</h1></div>\n        <div id='b1'>これは写真を表示するサンプルです</div>\n        <div id='c1'>これはc1です</div>\n        <div id='c2'>\n      <img src=\"{{{payload.image}}}\" style=\"width:100%;height:auto;\" />\n        </div>\n        <div id='c3'>これはc3ですよ</div>\n        <div id='d1'>これはd1です</div>\n    </div>\n  </body>\n</html>\n","x":550,"y":100,"wires":[["d9360f6e.c3bd2"]]},{"id":"2d4b4493.1fe804","type":"template","z":"2302eb53.652cc4","name":"css","field":"payload.css","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"#basic {\n    font-family: meiryo;\n    width: 1200px;\n    position: absolute;\n    top: 0;\n    left: 0;\n    right: 0;\n    bottom: 0;\n    margin: auto;\n}\n#a1 {\n    background-color:  #98d98e;\n    height: 100px;\n    padding: 20px;\n}\n#b1 {\n    background-color:  #e4de8a;\n    height: 100px;\n    text-align: center;\n    font-size: 18pt;\n}\n#c1 {\n    float: left;\n    background-color:  burlywood;\n    height: 533px;\n    width: 200px;\n    text-align: left;\n    font-size: 18pt;\n}\n#c2 {\n    float: left;\n    background-color:  wheat;\n    height: 533px;\n    width: 800px;\n}\n#c3 {\n    float: right;\n    background-color:  burlywood;\n    height: 533px;\n    width: 200px;\n    font-size: 18pt;\n}\n#d1 {\n    clear: both;\n    background-color:  rosybrown;\n    height: 100px;\n    text-align: left;\n    font-size: 18pt;\n}\n","x":250,"y":100,"wires":[["72030a24.31f77c"]]}]

画面を横方向に分割しています。

test24.css

#basic {
    font-family: meiryo;
    width: 1200px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
}
#a1 {
    background-color:  #98d98e;
    height: 100px;
    padding: 20px;
}
#b1 {
    background-color:  #e4de8a;
    height: 100px;
    text-align: center;
    font-size: 18pt;
}
#c1 {
    float: left;
    background-color:  burlywood;
    height: 533px;
    width: 200px;
    text-align: left;
    font-size: 18pt;
}
#c2 {
    float: left;
    background-color:  wheat;
    height: 533px;
    width: 800px;
}
#c3 {
    float: right;
    background-color:  burlywood;
    height: 533px;
    width: 200px;
    font-size: 18pt;
}
#d1 {
    clear: both;
    background-color:  rosybrown;
    height: 100px;
    text-align: left;
    font-size: 18pt;
}

float: leftで画面左側に寄せます
clear: bothでfloat設定を解除します