Dasmato's code review

Hi, I’m looking for some feedback on my code please. After seeing the solution and some of the other reviews on here I was quite surprised and impressed at how many different way there are of getting to the same conclusion! I had to change the h1 header font size from 100px to 55px to make it match the appearance of the spec sheet, but I have no idea why! lol
Thanks in advance! Here is my code:
html:

<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]>      <html class="no-js"> <!--<![endif]-->
<html>
    <head>
        <lang="en">
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <title>Dasmoto's</title>
        <meta name="description" content="Art Supplies">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="stylesheet" href="style.css">
    </head>

    <header>
        <h1>Dasmoto's Arts & Crafts</h1>
    </header>

    <body>
        <!--[if lt IE 7]>
            <p class="browsehappy">You are using an <strong>outdated</strong> browser. Please <a href="#">upgrade your browser</a> to improve your experience.</p>
        <![endif]-->
         <section>
            <h2 class="brushes">Brushes</h2>
            <img src="images/hacksaw.webp" alt="brush1" class="img-responsive">
            <h3>Hacksaw Brushes</h3> 
            <p>Made of the highest quality oak, Hacksaw Brushes are known for their weight and ability to hold paint in large amounts. Available in different sizes. <span>Starting at $3.00 / brush.</span></p>
        </section>
        <section>
            <h2 class="frames">Frames</h2>
            <img src="images/frames.webp" alt="paint1" class="img-responsive">
            <h3>Art Frames (assorted)</h3> 
            <p>Assorted frames made of different material, including MDF, birchwood, and PDE. Select frames can be sanded and painted according to your needs. <span>Starting at $2 / frame.</span></p>
        <section>
            <h2 class="paint">Paint</h2>
            <img src="images/finnish.jpeg" alt="paint1" class="img-responsive">
            <h3>Clean Finnish Paint</h3> 
            <p>Improved paint from Finland. Over 256 colors available in-store, varying in quantity (1 oz to 8oz.). Clean Finnish paint microbinds to canvas, increasing the finish and longevity of any artwork. <span>Starting at $5 / tube.</span></p>
        </section>
        <script src="" async defer></script>
    </body>
</html>

css:

header {
    text-align: center;
    font-family: Helvetica;
    font-size: 55px;
    font-weight: bold;
    color: khaki;
    background-image: url('images/pattern.webp');
}
.brushes {
    font-family: Helvetica;
    font-size: 32px;
    font-weight: bold;
    color: white;
    background-color: mediumspringgreen;
}
.frames {
    font-family: Helvetica;
    font-size: 32px;
    font-weight: bold;
    color: white;
    background-color: lightcoral;
}
.paint {
    font-family: Helvetica;
    font-size: 32px;
    font-weight: bold;
    color: white;
    background-color: skyblue;
}
h3 {
    font-family: Helvetica;
    font-size: 20px;
    font-weight: bold;
    color: black;
}
p {
    font-family: Helvetica;
    font-size: 16px;
    color: black;
}
span {
    font-family: Helvetica;
    font-size: 16px;
    color: blue;
    font-weight: bold;
}

Link to project: https://www.codecademy.com/paths/front-end-engineer-career-path/tracks/fecp-22-developing-websites-locally/modules/wdcp-22-developing-with-css/projects/dasmoto