<div class="box"></div>

<div class="form">
  <div class="control">
    <label for="border">border-width:</label>
    <input type="range" min="0" max="50" step="2" value="10" id="border" name="border" />
    <output id="output-border">10px</output>
  </div>
  <div class="control">
    <label for="opacity">border-opacity:</label>
    <input type="range" min="0" max="1" step=".1" value=".5" id="opacity" name="opacity" />
    <output id="output-opacity">0.5</output>
  </div>
  <div class="control">
    <label for="padding">padding:</label>
    <input type="range" min="0" max="50" step="5" value="10" id="padding" name="padding" />
    <output id="output-padding">10px</output>
  </div>
</div>

@import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100vw;
  min-height: 100vh;
  font-family: "Exo", Arial, sans-serif;
  background-color: #557;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1rem;
  gap: 1rem;
}

.box {
  --border: 10px;
  --opacity: 0.5;
  --padding: 10px;
  width: min(100%, 600px);
  background-color: #fff;
  aspect-ratio: 16 / 9;
  box-shadow: 0 0 10px 1px rgb(0 0 0 / 25%);
  border: var(--border) solid rgb(220 20 20 / var(--opacity));
  padding: var(--padding);
}

:root {
  --position: 0 0;
}

.box {
  background: #fff
    url("//www.w3cplus.com/sites/default/files/blogs/2022/2207/avatar.svg") left
    top / 100px 100px repeat;
  overflow: hidden;
  resize: both;
}

.form {
  padding: 1rem;
  background-color: rgb(0 0 0 / 0.6);
  backdrop-filter: blur(20px);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 10px;
}

.control {
  display: flex;
  align-items: center;
  justify-content: center;
}

input[type="range"] {
  width: min(100%, 80px);
}

label {
  white-space: nowrap;
}

const element = document.querySelector(".box");
const border = document.getElementById("border");
const padding = document.getElementById("padding");
const opacity = document.getElementById("opacity");

[border, padding].forEach((input) => {
  input.addEventListener("change", (etv) => {
    element.style.setProperty(`--${etv.target.id}`, `${etv.target.value}px`);
    document.getElementById(
      `output-${etv.target.id}`
    ).textContent = `${etv.target.value}px`;
  });
});

opacity.addEventListener("change", (etv) => {
  element.style.setProperty(`--${etv.target.id}`, `${etv.target.value}`);
  document.getElementById(
    `output-${etv.target.id}`
  ).textContent = `${etv.target.value}`;
});