Body that don't take the entire avaible space in an Electron app

I have an Electron app with personalized title bar (close and minimize button). When I show the border of all HTML elements in my window, I noticed that my body and my HTML tag don't take the entire window and I need that because I need to put border to my window. I don't know what is the problem, Thanks for your help.

I tried to put height: 100%; in CSS for HTML and body tag but that doesn't work. I also tried with margin: auto; but that doesn't work either.

Here is the screenshot of the app, first with height:100% (with a scrollbar and I don't want it) and second without.

The CSS:

*/*, *::after, *::before*/ {
  /* ~~~~~~ Disable elements dragging ~~~~~~ */
  -webkit-user-select: none;
  -webkit-user-drag: none;
  -webkit-app-region: no-drag;

  /* ~~~~~~~~~~~~~ Reset script ~~~~~~~~~~~~ */
  cursor: default;
  margin: 0;
  padding: 0;
  border: 2px solid blue;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}

html,
body {
  /*height: 100%;*/
  border: 4px solid red;
  background-color: #212121;
}

#TitleBar {
  -webkit-app-region: drag;
  background-color: #1a1a1a;
}

/* ##################################################################### */
/* ############################### Images ############################## */
/* ##################################################################### */
#Icon {
  width: 4%;
  height: 4%;
}

#ControlButtons {
  float: right;
}

#Close-Btn {
  width: 30px;
  height: 30px;
}

#Min-Btn {
  width: 30px;
  height: 30px;
}

The html:

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8" />
  <title>MyClipboard</title>
  <link rel="stylesheet" href="Styles/HomeStyle.css" />
</head>

<body>
  <div id="TitleBar">
    <img src="Images/clipboard_96px.png" id="Icon"></img>
    <div id="ControlButtons">
      <input type="image" id="Min-Btn" src="Images/minimize_window_96px.png">
      <input type="image" id="Close-Btn" src="Images/close_window_96px.png">

    </div>
  </div>
  <div id="Menu"></div>
  <div id="Content"></div>
  <script>
    require('./Control.js')
  </script>

</body>

</html>

Thanks for your response!