How can I make an element's attribute only appear on hover when another element is hidden?

I'm having trouble figuring out how to make the data-title only appear on hovering of the up-arrow only when the footer is down/not showing. However, I would also appreciate another solution where the data-title would still be visible when hovering the up-arrow even when the footer is up/showing. In this case, I would prefer the data-title to be displayed in its original position, up-right/0deg and on top of the up-arrow, rather than rotated 180deg and under the up-arrow.

I've tried using CSS and JavaScript to add and remove the data-title attribute, empty its innerHTML, and toggle its display, but nothing seems to work the way I want. Specifically, I was expecting the data-title to only appear on hover of an element (let's call it "Element A") when another element (let's call it "Element B") is hidden. Element A is the up-arrow, and I want the data-title to be shown on hover of Element A when Element B (the footer) is not visible on the page.

I suspect that the solution may be simple, but I'm struggling to figure it out. Any help or suggestions would be greatly appreciated.

// Get the up arrow element
const upArrow = document.getElementById("up-arrow");
const footer = document.querySelector(".slide-up-footer");
let isOpen = false;

// Add an event listener to toggle the "show" class
upArrow.addEventListener("click", toggleFooter);
upArrow.addEventListener("click", () => {
  footer.classList.toggle("show");
});
function toggleFooter() {
  if (isOpen) {
    footer.style.bottom = "-100%";
    upArrow.style.transform = "rotate(0deg)";
    upArrow.style.bottom = "0";
  } else {
    footer.style.bottom = "0";
    upArrow.style.bottom = "6%";
    upArrow.style.transform = "rotate(180deg)";
  }
  isOpen = !isOpen;
}

html {
    scroll-behavior:smooth;
  }

  body {
    font-family: 'Adobe Caslon Pro Bold', sans-serif;
    background-color: red;
    overflow: hidden;
  }
  body h1 {
    text-align: center;
  }
  

  .page-wrap {
    position: fixed;
    top: 10px;
    right: 10px;
    left: 10px;
    bottom: 10px;
    background: white;
    border-radius: 30px;
    padding: 20px;
    text-align: center;
    overflow: hidden;
  }
  
  .page-wrap h1 {
    margin: 0;
  }
  p {
    line-height: 3;
  }
  
  ::-webkit-scrollbar-track {
    background: none;
  }
  ::-webkit-scrollbar {
    width: 10px;
    height: 10px;
  }
  ::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 5px;
  }
  .slide-up-footer {
    display: flex;
    flex-direction: column;
    justify-content: center;
    font: 10px Fakt Soft, sans-serif;
    position: absolute;
    bottom: -1000px; /* or another value that will hide the footer */
    width: 100vw;
    height: 8%;
    transition: all 0.7s ease-in-out;
    background-color: white;
    
  }
  
  .slide-up-footer.show {
    bottom: 0;
  }
  
  .footer-text {
    display: grid;
    grid-row: 1/2;
    font: 12px Fakt Soft, sans-serif;
    color: black;
    text-align: center;
    padding: 10px;
    justify-content: center;
    position: relative;
  }

  .footer-text p{
    line-height: 0;
  }
  .up-arrow {
    transition: all 0.7s ease-in-out;
    position: absolute;
    bottom: 0px;
    right: 0px;
    margin: 2rem;
    z-index: 999;
  }
  .custom-class{
    font-weight: bold;
    font: 20px Fakt Soft, sans-serif;
    color:black;
    cursor: pointer;
    z-index: 999;
  }
 .custom-class:hover::before {
  content: "FOOTER";
  font: 12px Fakt Soft, sans-serif;
  position: absolute;
  background-color: transparent;
  color: black;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link href="https://fonts.googleapis.com/css2?family=Helvetica+Neue&display=swap" rel="stylesheet">
    <link rel="stylesheet" href="style.css" type="text/css">
    <title>Retro Step</title>
</head>

<body>
    <div class="page-wrap">
        <footer class="slide-up-footer">
            <div class="footer-text">
                <p>FREE SHIPPING IN PORTUGAL / IN EUROPE FROM 150€ / EASY RETURNS</p>
        </footer>
        <div class="up-arrow" id="up-arrow">
            <span class="custom-class" data-title="FOOTER">^</span>
        </div>
        <script src="script.js"></script>
    </div>
</body>

</html>

Solution

So apply a style when the sibling as the show class to hide it from view

.slide-up-footer.show + .up-arrow > .custom-class:hover::before { 
  display: none;
}

// Get the up arrow element
const upArrow = document.getElementById("up-arrow");
const footer = document.querySelector(".slide-up-footer");
let isOpen = false;

// Add an event listener to toggle the "show" class
upArrow.addEventListener("click", toggleFooter);
upArrow.addEventListener("click", () => {
  footer.classList.toggle("show");
});

function toggleFooter() {
  if (isOpen) {
    footer.style.bottom = "-100%";
    upArrow.style.transform = "rotate(0deg)";
    upArrow.style.bottom = "0";
  } else {
    footer.style.bottom = "0";
    upArrow.style.bottom = "6%";
    upArrow.style.transform = "rotate(180deg)";
  }
  isOpen = !isOpen;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Adobe Caslon Pro Bold', sans-serif;
  background-color: red;
  overflow: hidden;
}

body h1 {
  text-align: center;
}

.page-wrap {
  position: fixed;
  top: 10px;
  right: 10px;
  left: 10px;
  bottom: 10px;
  background: white;
  border-radius: 30px;
  padding: 20px;
  text-align: center;
  overflow: hidden;
}

.page-wrap h1 {
  margin: 0;
}

p {
  line-height: 3;
}

 ::-webkit-scrollbar-track {
  background: none;
}

 ::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

 ::-webkit-scrollbar-thumb {
  background: #ccc;
  border-radius: 5px;
}

.slide-up-footer {
  display: flex;
  flex-direction: column;
  justify-content: center;
  font: 10px Fakt Soft, sans-serif;
  position: absolute;
  bottom: -1000px;
  /* or another value that will hide the footer */
  width: 100vw;
  height: 8%;
  transition: all 0.7s ease-in-out;
  background-color: white;
}

.slide-up-footer.show {
  bottom: 0;
}

.footer-text {
  display: grid;
  grid-row: 1/2;
  font: 12px Fakt Soft, sans-serif;
  color: black;
  text-align: center;
  padding: 10px;
  justify-content: center;
  position: relative;
}

.footer-text p {
  line-height: 0;
}

.up-arrow {
  transition: all 0.7s ease-in-out;
  position: absolute;
  bottom: 0px;
  right: 0px;
  margin: 2rem;
  z-index: 999;
}

.custom-class {
  font-weight: bold;
  font: 20px Fakt Soft, sans-serif;
  color: black;
  cursor: pointer;
  z-index: 999;
}

.custom-class:hover::before {
  content: "FOOTER";
  font: 12px Fakt Soft, sans-serif;
  position: absolute;
  background-color: transparent;
  color: black;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
}

.slide-up-footer.show+.up-arrow>.custom-class:hover::before {
  display: none;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link href="https://fonts.googleapis.com/css2?family=Helvetica+Neue&display=swap" rel="stylesheet">
  <link rel="stylesheet" href="style.css" type="text/css">
  <title>Retro Step</title>
</head>

<body>
  <div class="page-wrap">
    <footer class="slide-up-footer">
      <div class="footer-text">
        <p>FREE SHIPPING IN PORTUGAL / IN EUROPE FROM 150€ / EASY RETURNS</p>
    </footer>
    <div class="up-arrow" id="up-arrow">
      <span class="custom-class" data-title="FOOTER">^</span>
    </div>
    <script src="script.js"></script>
    </div>
</body>

</html>