粗体标记导致线跳出div

Question

这是带有网格类和弹性项目的段落的代码。第一行为粗体，但粗体标记使该行跳到center_text_grid的左侧。

.center_text_grid {
  display: grid;
  grid-column: 5 / 12;
  grid-row: 20 / 20;
  display: block;
  overflow: auto;
  align-items: center;
  justify-items: center;
}

.mktg_text {
  font-family: CamphorW01-Thin, sans-serif;
  font-size: 13pt;
  color: rgb(175, 222, 162);
  line-height: 1.5;
}

<div class="center_text_grid flex-item mktg_text"><b>Thanks for your interest in our product.</b>&nbsp;&nbsp;We are excited to offer it, along with all accessories, six months ahead of schedule.&nbsp;&nbsp;The interest has been exceptional, and we appreciate all of the comments we received during its
  development.&nbsp;&nbsp;<br><br></div>

为什么加粗标记会导致该行跳出div？