some latex math equations can't be rendered

[zhiyuanpeng]

Describe the bug

After I run hugo, equation $\boldsymbol{X} \cup \boldsymbol{U}_{1}$ becomes $\boldsymbol{X} \cup \boldsymbol{U}<em>{1}$ in the corresponding .html file.

To Reproduce

Steps to reproduce the behavior:

1. Create a .md post with $\boldsymbol{X} \cup \boldsymbol{U}_{1}$
2. Run hugo

Technical details:

• Link to your GitHub project: https://github.com/zhiyuanpeng/zhiyuanpeng.github.io
• Wowchemy Version (from your go.mod):
  github.com/wowchemy/wowchemy-hugo-modules/wowchemy v0.0.0-20210324194200-fda9f39d872e // indirect
  github.com/wowchemy/wowchemy-hugo-modules/wowchemy-cms v0.0.0-20210324194200-fda9f39d872e // indirect
• Hugo Version (run hugo version): hugo v0.82.1-60618210+extended linux/amd64 BuildDate=2021-04-20T11:02:50Z VendorInfo=gohugoio
• Browser/OS: Chrome latest/ubuntu 20.04
• Wowchemy Template (e.g. Academic): Academic