I've tried adding an Electron WebView to a basic app and set minwidth and minheight on it as shown below. When it loads though it always ends up as 784px X 150px
<webview id="webpage" src="https://www.duckduckgo.com/" autosize="on" minwidth="800px" minheight="1200px"></webview>
This is an issue other people have reported too, here in atom discussion page under "Webview autosize" title :
https://discuss.atom.io/t/webview-autosize/16915/6
It seems that 'autosize' doesn't say the last word about the resulting window size; css parameters may interfere and change the result.
There are some css workarounds proposed for this issue that may help:
-Set html and body width to 100% :
html, body { width: 100%; height: 100%; margin: 0; padding: 0; }
-set viewport relative units in webview css:
webview { display: block; /* iframes are inline by default */ border: none; /* Reset default border */ height: 80vh; /* Viewport-relative units */ width: 95vw;
}