Fix ticket form's width

[int-y1]

/problem/aplusb/tickets/new
On narrow screens, width: 100%; causes overflow and looks bad.

[codecov-commenter]

Codecov Report

Base: 46.69% // Head: 46.68% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (0116ac7) compared to base (3947d2b).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2096      +/-   ##
==========================================
- Coverage   46.69%   46.68%   -0.01%     
==========================================
  Files         238      238              
  Lines       13236    13234       -2     
==========================================
- Hits         6180     6178       -2     
  Misses       7056     7056              

Impacted Files	Coverage Δ
judge/utils/unicode.py	52.17% <0.00%> (-3.83%)	⬇️

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[Xyene]

LGTM, but it looks like with this change + narrow screen, there is more padding on the left side than the right?

[int-y1]

LGTM, but it looks like with this change + narrow screen, there is more padding on the left side than the right?

This affects other forms too. Forms have 15px left pad, and 10px right pad, because of

online-judge/resources/base.scss

Lines 86 to 92 in a5eb182

	.form-area {
	display: inline-block;
	background: $color_primary5;
	padding: 5px 10px 10px 15px;
	border-radius: $widget_border_radius;
	border: 1px solid $color_primary25;
	}

I suspect that this is a typo that wasn't corrected.