🐛 [Bug]: Fibonacci Input Field Text Invisible in Dark Mode + Input Validation Issues

[snehanair-486]

Description
Two related bugs found in the Fibonacci Series project:

Bug 1 — Dark Mode Text Visibility
In dark mode, the input field is completely invisible — both the default value (10) and any text the user types cannot be seen. The field appears empty even when it contains values.

Steps to reproduce:

1. Switch to dark mode
2. Click the Fibonacci Series project card
3. Notice the input field looks empty — the default value 10 is there but invisible
4. Try typing a number like 6 — nothing appears visually
5. Click the spinner arrows (up/down) on the input field — the number briefly becomes visible
6. But now the value is wrong e.g. 1064 because 10 was silently there from the start, then you typed 64 on top of it

Bug 2 — Input Validation Not Working
The input field accepts invalid values and handles them incorrectly instead of showing an error message.

Steps to reproduce:

1. Type -1 → the project silently outputs 0 with no error or explanation
2. Type 000 → the project treats it as valid and generates the first 10 Fibonacci numbers as if the input was 10, with no feedback to the user that their input was corrected or invalid

Expected Behaviour

• Input field text should be clearly visible in both light and dark mode
• Negative numbers should show a clear error message e.g. "Please enter a positive number"
• Zero or invalid inputs like 000 should show a clear error message e.g. "Please enter a number greater than 0"
• No silent corrections — if the input is wrong, tell the user explicitly

hi @steam-bell-92, I'd love to work on this! Please assign it to me.

[github-actions]

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