HTML Guide

CSS: “background”: X is not a “background-color” value.

There’s an invalid value for the background property in your CSS. The W3C HTML Validator has attempted to match the value to a background color, without success.

Here’s how to resolve this issue:

Identify the Correct CSS Configuration: The background property in CSS can take various forms, such as a color, an image, or a combination of background components. Ensure you provide a valid value.
Correct the Value: If you meant to set a background color, use a valid color format (e.g., hexadecimal, RGB, RGBA, named color, etc.).

Valid CSS Examples:

Using a named color:
```
.example {
  background: blue;
}
```
Using a hexadecimal color:
```
.example {
  background: #00ff00;
}
```

Using an RGB color:

.example {
  background: rgb(255, 0, 0);
}

Using an RGBA color (with transparency):

.example {
  background: rgba(255, 0, 0, 0.5);
}

Setting an image as background:

.example {
  background: url('image.jpg');
}

Combining multiple background properties:

.example {
  background: url('image.jpg') no-repeat center/cover;
}

Learn more:

Related W3C validator issues

CSS: “background-color”: Lexical error at line L, column C. Encountered: ";" (59), after : "#".

This error typically occurs when there is a syntax issue in the CSS code for the background-color property in your HTML or CSS file. The error message indicates that there is an unexpected semicolon (;) after the # symbol, which is commonly used to define hexadecimal color values.

Here is a step-by-step guide to fix this issue:

Locate the Error:
- Look for the line and column in your code as specified by the validator. This is where the error is occurring.
Identify the Issue:
- Check the background-color property at that location. It’s likely that you have a semicolon directly after the # or an invalid color value.
Correct the Syntax:
- Ensure that the background-color property is followed by a valid hexadecimal color value, an RGB/RGBA value, an HSL/HSLA value, or a predefined color keyword.

Example of Error

Let’s say you have the following erroneous CSS code:

body {
    background-color: #; /* Incorrect */
}

The above code is incorrect because #; is not a valid color value.

Corrected Example

Here’s how to fix it by providing a valid hexadecimal color value:

body {
    background-color: #ffffff; /* Correct: Hexadecimal color for white */
}

Alternatively, you can also use other color formats or color keywords. Examples:

body {
    background-color: rgb(255, 255, 255); /* RGB color */
}

body {
    background-color: rgba(255, 255, 255, 1); /* RGBA color */
}

body {
    background-color: hsl(0, 0%, 100%); /* HSL color */
}

body {
    background-color: hsla(0, 0%, 100%, 1); /* HSLA color */
}

body {
    background-color: white; /* Predefined color keyword */
}

CSS: “background-color”: “X” is not a “background-color” value.

The background-color property in CSS expects a valid color value. Valid color values include keywords (such as red or blue), hexadecimal values (such as #FFFFFF), RGB values (such as rgb(255, 255, 255)), and others.

Example Fix

Invalid CSS

The following snippet is invalid because 0 is not a valid color value:

<style>
  .example {
    background-color: 0;
  }
</style>

Valid CSS

To fix it, use a valid color value. Below are examples using different types of color values:

Color Keyword

<style>
  .example {
    background-color: black;
  }
</style>

Hexadecimal Color

<style>
  .example {
    background-color: #000000;
  }
</style>

RGB Color

<style>
  .example {
    background-color: rgb(0, 0, 0);
  }
</style>

RGBA Color

<style>
  .example {
    background-color: rgba(0, 0, 0, 0.5);
  }
</style>

CSS: “grid-column”: X is not a “grid-column” value.

The issue you’re encountering pertains to the use of the grid-column property in CSS, which is part of the CSS Grid Layout module. The grid-column property is typically used to specify how elements are placed along the grid columns in a grid layout.

The grid-column property is a shorthand for specifying both the starting grid line and the ending grid line for a grid item in order to define its horizontal position in the grid. The correct way to use it generally involves setting either a specific line number or a span value.

Syntax

The basic syntax for the grid-column property is:

grid-column: <start-line> / <end-line>;

<start-line>: The grid line where the item starts. This can be a line number, a named grid line, or a span keyword.
<end-line>: The grid line where the item ends. Similarly, this can also be a line number, a named grid line, or use span to indicate spanning across a number of lines.

Common Usage

Specific Lines: Specify the starting and ending lines explicitly.
```
grid-column: 2 / 4;
```
This would place the item starting from line 2 and ending before line 4.
Spanning Columns: Use the span keyword to define how many columns you want the item to span.
```
grid-column: 1 / span 2;
```
This would start the item at line 1 and span two columns.

Issue with grid-column: 0

The value 0 is invalid for grid-column because grid lines in CSS Grid Layout are indexed starting from 1. Attempting to use 0 implies a non-existent line and therefore results in an invalid value error.

Correcting the Issue

Determine which grid line your item should start from and which line it should end on, using valid line numbers or span values.
Update your CSS to use valid grid lines:
```
/* Correct usage example: */
.grid-item {
  grid-column: 1 / span 2;
}
```
Here, the grid item starts at line 1 and spans across 2 columns.

Ensure that your grid layout is properly set up with the desired number of rows and columns so that you can appropriately set valid grid-column values.

CSS: “grid-template-rows”: X is not a “grid-template-rows” value.

The specified value for the grid-template-rows property is not valid. This CSS property specifies the height of each row in a CSS grid layout.

Correct Usage of grid-template-rows

The grid-template-rows property accepts several types of values:

Length values (e.g., px, em, rem):
```
grid-template-rows: 100px 200px;
```
Percentages:
```
grid-template-rows: 50% 50%;
```
Flexible units (fr):
```
grid-template-rows: 1fr 2fr;
```
Auto keyword:
```
grid-template-rows: auto auto;
```
Repeat function:
```
grid-template-rows: repeat(3, 1fr);
```

Minmax function:

grid-template-rows: minmax(100px, 200px) auto;

Example

Here’s an example where we define two rows, one with a height of 100px and the other one of 200px.

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Example of grid-template-rows</title>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    .grid-container {
      display: grid;
      grid-template-rows: 100px 200px;
    }
  </style>
</head>
<body>
  <div class="grid-container">
    <div>Row 1</div>
    <div>Row 2</div>
  </div>
</body>
</html>