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Arbitrary color values in Tailwind - Mini Project: Build & Apply

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Using Arbitrary Color Values with Tailwind CSS
📖 Scenario: You are creating a simple webpage section that needs a custom background color and text color not included in Tailwind's default palette.
🎯 Goal: Build a <section> with a background color of #4a90e2 and text color of #f5a623 using Tailwind CSS arbitrary color values.
📋 What You'll Learn
Use Tailwind CSS arbitrary values for background and text colors
Create a <section> element with the specified colors
Include accessible semantic HTML
Make sure the text is readable on the background color
💡 Why This Matters
🌍 Real World
Web designers often need colors outside the default palette. Using arbitrary values lets you match brand colors exactly.
💼 Career
Knowing how to use Tailwind's arbitrary values helps you customize designs quickly and precisely in real projects.
Progress0 / 4 steps
1
Create the HTML skeleton with a <section>
Write the basic HTML structure with a <section> element containing the text Custom Colors Section inside the <body>.
Tailwind
Hint

Use a <section> tag inside the <body> with the exact text Custom Colors Section.

2
Add Tailwind classes for padding and font size
Add Tailwind CSS classes p-6 and text-lg to the <section> element to add padding and increase the font size.
Tailwind
Hint

Add the classes p-6 and text-lg inside the class attribute of the <section>.

3
Apply arbitrary background color using Tailwind
Add the Tailwind class bg-[#4a90e2] to the <section> element to set the background color to #4a90e2.
Tailwind
Hint

Use the class bg-[#4a90e2] exactly inside the class attribute.

4
Add arbitrary text color for contrast
Add the Tailwind class text-[#f5a623] to the <section> element to set the text color to #f5a623 for good contrast.
Tailwind
Hint

Add the class text-[#f5a623] inside the class attribute of the <section>.

Practice

(1/5)
1. What is the purpose of using arbitrary color values in Tailwind CSS?
bg-[#ff5733]
easy
A. To create animations with colors
B. To use any custom color not in Tailwind's default palette
C. To add shadows to elements
D. To change font sizes dynamically

Solution

  1. Step 1: Understand Tailwind's default colors

    Tailwind provides a set of default colors but sometimes you need a specific shade not included.

  2. Step 2: Use arbitrary color values

    By writing colors inside square brackets like bg-[#ff5733], you can use any valid CSS color.

  3. Final Answer:

    To use any custom color not in Tailwind's default palette -> Option B

  4. Quick Check:

    Arbitrary colors = custom colors [OK]
Hint: Square brackets let you add any color code directly [OK]
Common Mistakes:
  • Thinking arbitrary colors create animations
  • Confusing color usage with font size changes
  • Using arbitrary colors for shadows instead of colors
2. Which of the following is the correct syntax to set a background color to a semi-transparent red using arbitrary values in Tailwind CSS?
easy
A. bg-[rgba(255,0,0,0.5)]
B. bg-rgba(255,0,0,0.5)
C. bg-[rgb(255,0,0,0.5)]
D. bg-(rgba(255,0,0,0.5))

Solution

  1. Step 1: Check the correct use of square brackets

    Arbitrary values must be inside square brackets exactly, so bg-[...] is correct.

  2. Step 2: Validate the color function syntax

    The color function rgba(255,0,0,0.5) is valid CSS and correctly placed inside brackets.

  3. Final Answer:

    bg-[rgba(255,0,0,0.5)] -> Option A

  4. Quick Check:

    Correct brackets + valid rgba = bg-[rgba(255,0,0,0.5)] [OK]
Hint: Always wrap color values in square brackets for arbitrary colors [OK]
Common Mistakes:
  • Omitting square brackets
  • Using parentheses instead of brackets
  • Using rgb instead of rgba for transparency
3. What color will the text be if you use this Tailwind class?
text-[hsl(120,100%,50%)]
medium
A. Bright green
B. Bright red
C. Bright blue
D. Bright yellow

Solution

  1. Step 1: Understand HSL color values

    HSL stands for hue, saturation, and lightness. Hue 120° corresponds to green.

  2. Step 2: Analyze saturation and lightness

    100% saturation and 50% lightness means the color is bright and fully saturated green.

  3. Final Answer:

    Bright green -> Option A

  4. Quick Check:

    Hue 120° = green [OK]
Hint: Hue 120° in HSL means green color [OK]
Common Mistakes:
  • Confusing hue degrees with other colors
  • Ignoring saturation and lightness effects
  • Assuming default Tailwind colors instead of arbitrary
4. Identify the error in this Tailwind class:
bg-[#12345G]
medium
A. Missing square brackets
B. Wrong prefix, should be 'background-'
C. Invalid hex color code due to 'G'
D. Hex code too short

Solution

  1. Step 1: Check hex color validity

    Hex colors only allow digits 0-9 and letters A-F (case-insensitive). 'G' is invalid.

  2. Step 2: Confirm brackets and prefix

    Square brackets and prefix bg- are correct here.

  3. Final Answer:

    Invalid hex color code due to 'G' -> Option C

  4. Quick Check:

    Hex digits must be 0-9 or A-F [OK]
Hint: Hex colors only use 0-9 and A-F letters [OK]
Common Mistakes:
  • Ignoring invalid hex characters
  • Thinking brackets are missing
  • Confusing prefix names
5. You want a button with a background color that changes based on light or dark mode using arbitrary colors. Which Tailwind class combination is correct?
hard
A. bg-[rgb(255,255,255)] dark:bg-[rgb(300,300,300)]
B. bg-[rgb(255,255,255)] bg-dark:[rgb(30,30,30)]
C. bg-[rgb(255,255,255)] dark:bg(rgb(30,30,30))
D. bg-[rgb(255,255,255)] dark:bg-[rgb(30,30,30)]

Solution

  1. Step 1: Use correct dark mode prefix

    Tailwind uses dark: prefix to apply styles in dark mode.

  2. Step 2: Use correct arbitrary color syntax

    Colors must be inside square brackets with valid CSS color values.

  3. Step 3: Validate color values

    RGB values must be between 0 and 255; bg-[rgb(255,255,255)] dark:bg-[rgb(300,300,300)] has invalid 300 values.

  4. Final Answer:

    bg-[rgb(255,255,255)] dark:bg-[rgb(30,30,30)] -> Option D

  5. Quick Check:

    Correct dark: prefix + valid colors = bg-[rgb(255,255,255)] dark:bg-[rgb(30,30,30)] [OK]
Hint: Use dark: prefix and brackets for dark mode colors [OK]
Common Mistakes:
  • Using wrong dark mode prefix syntax
  • Omitting square brackets for arbitrary colors
  • Using invalid RGB values above 255