Get element by class list doesn’t seem to work in a for loop [duplicate]

I tried to create a for loop which loops through all buttons in an array I made – and it’s supposed to work according to: (https://www.w3schools.com/js/js_loop_for.asp)

But it does not.

I have no idea what should I do, since I haven’t found anything about that on the web.
Thank you for your time.

Here is the code

const buttons = document.getElementsByClassName('zoom-btn');

for (i = 0; i < buttons.length; i++) {
    buttons[i].onmouseover = () => {
        buttons[i].style.backgroundColor = "red";
    }
};

#article-navbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    align-content: center;

    position: fixed;

    width: clamp(286px, 504px, 506px);
    height: clamp(90px, 182px, 184px);

    top: 36vw;
    left: 4vw;

    background-color: cyan;
}

.zoom-btn {
    background-color: slategray;
    color: white;

    padding: 18px 10px;
    margin-top: 12px;
    margin-left: 10px;

    font-size: 16px;

    position: relative;
}

.reset-btn {
    background-color: blue;
}

.zoom-hover {
    background-color: red;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <link rel="stylesheet" href="a.css">
</head>
<body>
    <div id="article-navbar">

        <a id="button-RE" ; class="zoom-btn reset-btn">Reset</a>
        <a id="button-A1" ; class="zoom-btn">Block 1</a>
        <a id="button-A2" ; class="zoom-btn btn-deactivated">Block 2</a>
        <a id="button-A3" ; class="zoom-btn btn-deactivated">Block 3</a>
    
        <a id="button-B1" ; class="zoom-btn btn-deactivated">Block 4</a>
        <a id="button-B2" ; class="zoom-btn btn-deactivated">Block 5</a>
    
      </div>

    <script src="a.js"></script>
</body>
</html>