[Bug] When the content contains two font sizes, the toolbar font size is displayed incorrectly

[oumomomo]

Before you submit this issue, have you checked the following

• Is this really a problem?
• I have searched the Github Issues for similar issues, but did not find anything.

Affected packages and versions

dev

Reproduction link

操作步骤：
1、输入内容，将内容前半段字号设置为72号，后半段字号设置为20号
2、在72号字号区域输入内容，再回到后半段输入内容
3、观察工具栏字号

Expected behavior

在前半段输入内容再回到后半段输入，工具栏展示为后半段的20号

Actual behavior

在前半段输入内容再回到后半段输入，工具栏展示为72号

https://github.com/dream-num/univer/assets/167171356/053f8afb-6331-422f-b639-26f73a886c61

System information

No response

[univer-bot]

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Origin Title: [Bug] 内容包含两种字号时，工具栏字号展示有误

Title: [Bug] When the content contains two font sizes, the toolbar font size is displayed incorrectly

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Before you submit this issue, have you checked the following

• Is this really a problem?
• I have searched the Github Issues for similar issues, but did not find anything.

Affected packages and versions

dev

Reproduction link

Steps:

1. Enter the content and set the font size of the first half of the content to 72 and the font size of the second half to 20.
2. Enter the content in the font size area 72, and then return to the second half to enter the content.
3. Observe the toolbar font size

Expected behavior

Enter the content in the first half and then return to the second half. The toolbar will display the number 20 in the second half.

Actual behavior

Enter content in the first half and then return to the second half. The toolbar will display number 72.

https://github.com/dream-num/univer/assets/167171356/053f8afb-6331-422f-b639-26f73a886c61

System information

No response