diff --git a/src/config.sty b/src/config.sty
index 9119012..9dfd415 100644
--- a/src/config.sty
+++ b/src/config.sty
@@ -25,6 +25,7 @@ anchorcolor = blue]{hyperref}
 \onehalfspacing{}
 
 \usepackage{tikz}
+\usetikzlibrary{shadows}
 \usetikzlibrary{arrows.meta}
 \newcommand{\tikzwidth}{0.95\columnwidth}
 \newcommand{\tikzheight}{0.7\columnwidth}