Fix garbled characters and hbox warnings with pdflatex.

doc/example/spine.tex

@@ -1,13 +1,13 @@
 % Copyright (c) 2018 Casper Ti. Vector
 % Public domain.
 
-\documentclass[zihao = -4]{ctexart}
+\documentclass[UTF8, zihao = -4]{ctexart}
 \usepackage{calc, geometry, graphicx}
 \usepackage[defaultsups]{newtxtext}
 \usepackage[cmintegrals, varg]{newtxmath}
 \pagestyle{empty}
 \newlength{\colpad}
-\newcommand{\colwidth}{\ccwd}
+\newcommand{\colwidth}{0.99\ccwd}
 
 % 设定论文纸尺寸。
 \geometry{paperwidth = 460mm, paperheight = 297mm, margin = 0cm}