I’ve made the stylesheet below for my website, developing with desktop in mind, specifying a font-size for the body element and doing everything else relative to that (using em). Now I’d like to be able to set a larger font-size for when the website is viewed on a mobile phone, so I’ve added a simple media query. My flow to try testing is:

• delete browsing data in my browser (Chrome)
• start the local server, with homepage open in browser, with width > 600px
• confirm with inspect that body text uses font-size 16px, coming from style.css
• resize screen width to <600px, and reload the browser window (in case it’s needed)

Result: this body text still uses font-size 16px, coming from style.css, rather than 20px, as I have in my little media query.

Can anyone spot what I have wrong in my media query, my stylesheet, or my work flow? Thanks in advance for any ideas!

:root {
  --link-color: #99CC66;
  --header-color: #666869;
  --header-hover: #131213;
}

.navbar li{
  display: inline-block;
  vertical-align: text-top;
  margin-left: 15px;
  margin-right: 15px;
  list-style-type:none;
  font-size: 1.25em;
}

.navbar a {
    color: var(--header-color) !important;
}
.navbar a:hover {
    color: var(--header-hover) !important;
  text-decoration: none;
}
.navbar-brand {
  font-size: 1em;
}

body    {
      font-size: 16px;
}

p           { font-size: 1em;
            text-indent: 1em}


.circled_section {
    border-radius: 25px;
    border: 5px solid var(--link-color);
    padding: 15px;
    margin-top: 10px;
    margin-bottom: 10px;
}

.one_branch_display {
  margin: 30px;
  width: 35%;
}

.two_branch_display {
  margin: 20px;
  width: 35%;
}

.four_branch_display {
  margin: 5px;
  width: 23%;
}

.container {
  margin-right: auto;
  margin-left: auto;
  padding-left: 15px;
  padding-right: 15px;
  max-width: 1320px !important;
}
  .container:before,
  .container:after {
    content: " ";
    display: table; }
  .container:after {
    clear: both; }


  /* Increase the font size on mobile devices */
   @media only screen and (max-width: 600px) {
    body {
    font-size: 20px;
  }}


/* family generation display colors */
.g3 { font-size: 1em; text-decoration: underline;  color: #8b8378; }
.g4 { font-size: 1em; text-decoration: underline;  color: #FFCC66; }
.g5 { font-size: 1em; text-decoration: underline;  color: #FF66CC; }
.g6 { font-size: 1em; text-decoration: underline;  color: #99CC66; }
.g7 { font-size: 1em; text-decoration: underline;  color: #000066; }
.g8 { font-size: 1em; text-decoration: underline;  color: #663300; }
.g9 { font-size: 1em; text-decoration: underline;  color: #8A5C8A; }
.g10 { font-size: 1em; text-decoration: underline;  color: #75A3A3; }
.g11 { font-size: 1em; text-decoration: underline;  color: #000000; }
.g12 { font-size: 1em; text-decoration: underline;  color: #8A5C5C; }
.g13 { font-size: 1em; text-decoration: underline;  color: #006699; }
.g14 { font-size: 1em; text-decoration: underline;  color: #CC9933; }
.g15 { font-size: 1em; text-decoration: underline;  color: #5C8A73; }
.g16 { font-size: 1em; text-decoration: underline;  color: #CC99B3; }

/*Styles for image gallery hover text:*/
.image_container {
  position: relative;
}

.image {
  display: block;
  width: 100%;
  height: auto;
}

.overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  transition: .5s ease;
  background-color: var(--link-color);
}

.image_container:hover .overlay {
  opacity: 1;
}

.text {
  color: white;
  font-size: 1em;
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  text-align: center;
}