Width of responsive dropdown menu shrinks too much at smaller screen sizes-CodePudding

I'm a beginner Web Developer who is currently working on my first responsive website. I’ve run into an issue with my dropdown menu where the width (which I want to cover the whole screen) begins to reduce when the screen size passes a certain threshold (484 pixels or less). I had a similar issue in other areas of my site that after some research I was able to fix by adding “mid-width: fit-content;” to my HTML ruleset, but it doesn’t seem to be helping the dropdown. Any idea what could be causing this? I’ve been unable to find a cause or solution so any advice would be greatly appreciated.

Below is a simplified version of my code:

<!DOCTYPE html>
<html lang = "en">
    <head>
        <meta charset="UTF-8">
        <title>A Website</title>
        <link rel="stylesheet" href="./styles/MenuTestCSS.css">
        <meta name="viewport" content="width=device-width">
    </head>
    <body>        
        <header>
            <div class="flexContainer">
                <div id="logoBox">
                    <h2 id="logo">Website</h2>
                </div>
                <nav>   
                    <ul id="menu" class="flexContainer">
                        <li class = "navLink"><a href="" >Link</a></li>
                        <li class = "navLink"><a href="">Link</a></li>
                        <li class = "navLink"><a href="">Link</a></li>
                        <li class = "navLink"><a href="">Link</a></li>
                    </ul> 
                    <div class="flexContainer">
                        <div id="menuToggle">           
                            <div class="square"></div>
                            <div class="square"></div>
                            <div class="square"></div>
                        </div>
                    </div>
                </nav>
            </div>
        </header>
    </body>
</html>

/* GENERAL STYLES */

html {
    box-sizing: border-box;
    min-width: fit-content; 
}

body {
    width: 100%;
}

*, *::before, *::after {

    box-sizing: inherit;
    margin: 0;
    padding: 0;
}

.flexContainer{
    display: flex;
    flex-flow: row wrap;
}

/* HEADER STYLES */

header {
    color: white;
    background-color: #485696;
    height: auto;
}

header .flexContainer {
    align-items: center;
    height: 100%;
    width: 100%;
}

header h2 {
    font-size: 48px;
    margin: 20px 0;
    padding-left: 25px;
}

nav {
    align-self: stretch;
    width: 485px;

}

nav .flexContainer {
    justify-content: space-around;
}

header a, header a:visited {
    color: white;
    text-decoration: none;
    font-size: 26px;
}

header li {
    display: inline-block;
}

#menuToggle {
    width: 45px;
    height: 50px;
    display: none;
}

.square{
    width: 45px;
    background-color: white;
    height: 5px;
}

.square   .square {
    margin-top: 10px;
}

nav {
    flex: 1 0 0;
}

nav .flexContainer {
    justify-content: flex-end;
}


#menuToggle {
    margin-right: 3em;
    width: 30px;
    height: 30px;
    display: block;
}

#menu {
    background-color:#485696;
    position: absolute;
    top: 92px;
    left: 0%;
    height: auto;
    padding: 10px 25px;
    display: block;
    border-top: 4px solid white;
}

.navLink   .navLink {
    margin-top: 1em;
}

#menu li {
    display: block;
}

.navLink   .navLink {
    margin-left: 0px;
}

CodePudding user response：

You've got this issue because you set nav{ width: 485px } so it's logically will be shrinked when the with is lower than 485px, I notice you to learn about relative lengths such as "%", "rem", "em", "vh"... so in your case you'll just change the nav { width: 485px } by width: 100%