Input Errors and Unexpected Behavior in Aspect Ratio Calculator

**Description:**

1. Typing `0` in W1 or H1 results in NaN values for W2 and H2.
2. Typing `-` in W1 or H1 throws an error.
3. Typing `-` in W2 or H2 results in NaN values for W2 and H2.
4. On presets (e.g., 16:9, 3:2, and others), typing certain numbers causes unexpected rounding or alterations, such as typing `4` in W2 changes it to `4.01`, typing 1 in W2 changes it to `1.01`, and typing 6 changes it to `5.99`. This issue persists regardless of whether "round results" is enabled.

**Expected Behavior:**

- Inputs should handle zeros and negative signs correctly without causing NaN values or errors.
- Typing numbers should not cause unexpected rounding or alterations, and values should stay as entered by the user.