restrict the level of headings in the sticky table of contents

[govin08]

I want to restrict the level of headings displayed in the sticky toc.

Here is my sample post.

# Chapter 1. The Genesis of Fourier Series

## 1. The vibrating string

#### Simple harmonic motion

Consider a mass $m$ attached to a horizontal spring.
Let $y(t)$ be the displacement of the mass at time $t$ where the equilibrium position is set to $y=0$.
By Hooke's law and Newton's law,

$$-ky(t)=my''(t)$$

#### Standing and traveling waves
One dimensional wave can be described as a function $y=u(x,t)$.
That is, we can specify the vertical displacement $y$ of a wave depending on the horizontal displacement $x$ and time $t$.

#### Harmonic and superposition of tones

(quote without any modification) The pure tones are accompanied by combinations of overtones which are responsible for the timbre of the instrument.

### 1.1 Derivation of the wave equation

Consider a horizontal string of length $L$.
For sufficiently large integer $N$, subdivide the string into $N$ *particles* evenly.
$n$-th particle at $x=x_n=\frac nNL$ move vertically only.
And the only forces on the particle are the tensions from the neighboring particles ;

### 1.2 Solution to the wave equation

<!-- There are two kinds of solution to the wave equation ; -->
We can get two kinds of solution to the wave equation ;
(1) using traveling waves
(2) using the superposition of standing waves

#### A solution using traveling waves

Consider a physical problem of a string where $0\le x\le \pi$ 

In this post, the first heading is chapter, the second is section and the third is subsection. And I want this three heading to be numbered and want them to be represented in the sticky TOC. The fourth heading is just a paragraph and it doesn't need to be displayed in the sticky TOC. Only numbered headings (chapter, section, subsection) need to be displayed in the sticky TOC.

In this sense, can I restrict the level of headings in the sticky TOC?

If it is not possible, I can boldify the paragraph instead. But making it bold is not enough. There are another bold words, so at least I have to be able to magnify them (make the words of the heading of the paragraph bigger).