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December 17

Making buttons to change the colors on a page.

I had buttons on a site that changed the bgcolor and text color back and forth between "day time" and "night time." The code just changed the default colors. But now I want to use to as declaring variables, i.e., color1, color2, which can change, upon button click. Here's what I have

<style type="text/css">
		body.theme-day { color1: green; color2: red; color3: lightgray; }
		body.theme-night { color1: darkgreen; color2: darkred; color3: gray; }

		/* hide elements for the opposite theme 
		body.theme-day .theme-night { display: none; }
		body.theme-night .theme-day { display: none; }
         */
	</style>
	<script type="text/javascript">
		function change_theme(theme) {
			document.body.className = document.body.className.replace(/\s*theme-\S+/, "") + " theme-" + theme;
		}
	</script>
//And then the buttons.
<P align="center"><button class="theme-night" type="button" onclick="change_theme('day');">Day version</button>
<button class="theme-day" type="button" onclick="change_theme('night');">Night version</button></P>

And so my issue is, using color1 and color2 are not recognized, say, when I use font color="color1" for example. Thanks. 67.165.185.178 (talk) 16:29, 17 December 2022 (UTC).[reply]

I'm not used to CSS, but I had a look at the relevant page on W3Schools.

Variables: it seems that their names have to start with --, so you would have to say --color1: green; --color2: red;, and so on. Then, it seems that you have refer to them using the var() function. So rather than saying style="color: color2;" it would be style="color: var(--color2);". Card Zero (talk) 22:07, 17 December 2022 (UTC)[reply]

Okay, I got half of it to work. The part that works is

th, td {
  border: 2px solid var(--color2);
}

(Above is all within <style> tags. But the part that doesn't work is <body style="bgcolor: var(--color3);">,

<table style="bgcolor: var(--color3);">

, and

<td style="bgcolor: var(--color1); width:83%">

67.165.185.178 (talk) 00:08, 18 December 2022 (UTC).[reply]

Is it possibly background-color rather than bgcolor?

Here's a complete functioning page.

<!DOCTYPE html>
<html>
<head>
<style>
#customers {
  font-family: Arial, Helvetica, sans-serif;
  border-collapse: collapse;
  width: 100%;
}

#customers td, #customers th {
  border: 2px solid var(--color2);
  padding: 8px;
}

#customers tr:nth-child(even){background-color: #f2f2f2;}

#customers tr:hover {background-color: #ddd;}

#customers th {
  padding-top: 12px;
  padding-bottom: 12px;
  text-align: left;
  background-color: #04AA6D;
  color: white;
}

		body.theme-day { --color1: green; --color2: red; --color3: lightgray; }
		body.theme-night { --color1: darkgreen; --color2: darkred; --color3: gray; }
</style>
<script type="text/javascript">
	function change_theme(theme) {
		document.body.className = document.body.className.replace(/\s*theme-\S+/, "") + " theme-" + theme;
	}
</script>
</head>

<body class="theme-day" style="background-color: var(--color3);">

<h1>A Fancy Table</h1>

<table id="customers" style="background-color: var(--color3);">
  <tr>
    <th>Company</th>
    <th>Contact</th>
    <th>Country</th>
  </tr>
  <tr>
    <td>Alfreds Futterkiste</td>
    <td>Maria Anders</td>
    <td style="background-color: var(--color1); width:83%">Germany</td>
  </tr>
  <tr>
    <td>Berglunds snabbköp</td>
    <td>Christina Berglund</td>
    <td>Sweden</td>
  </tr>
  <tr>
    <td>Centro comercial Moctezuma</td>
    <td>Francisco Chang</td>
    <td>Mexico</td>
  </tr>
</table>

<P align="center"><button class="theme-night" type="button" onclick="change_theme('day');">Day version</button>
<button class="theme-day" type="button" onclick="change_theme('night');">Night version</button></P>

</body>
</html>

Card Zero (talk) 00:49, 18 December 2022 (UTC)[reply]

Okay, got it to work, it was indeed background-color. 67.165.185.178 (talk) 01:07, 18 December 2022 (UTC).[reply]

Wikipedia:Reference desk/Archives/Computing/2022 December 17

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December 17

Making buttons to change the colors on a page.