How to Make Background Image Responsive with CSS?

html {
  height: 100vh;
  width: 100vw;
}

body {
  height: 100%;
  width: 100%;
  overflow: hidden;
  background-image: url('https://wallpapers.com/images/featured/1920-x-1080-night-city-y13hx1qucv0ztepv.jpg');
  background-size: cover;
  background-repeat: no-repeat;
  background-position: center;
  display: flex;
  justify-content: center;
  align-items: center;
}

h2 {
  text-align: center;
  font-weight: 600;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

.container {
  min-height: 40%;
  max-width: 60%;
  border: 1px solid black;
  border-radius: 3%;
  background-color: white;
  padding: 0 10px 10px 10px;
}

.question {
  font-size: 1.1rem;
  padding: 0 0 15px 0;
  border-bottom: 2px solid black;
  cursor: pointer;
}

.question::after {
  content: "+";
  font-size: 1.4rem;
  position: absolute;
  right: 10px;
}

.answer {
  overflow: hidden;
  height: 0;
  transition: all 0.5s ease-in;
}

.question-container.active .answer {
  height: 40px;
}

.question-container.active .question {
  font-size: 1rem;
  transition: all 0.5s ease-in;
}

.question-container .active .question::after {
  content: "-";
  transition: all 0.5s ease-in;
}

<div class="container">
  <h2>Frequently Asked Questions</h2>
  <div class="question-container">
    <p class="question">What is the return policy?</p>
    <p class="answer">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Veniam porro quidem eum praesentium officia voluptas repellendus amet minima alias voluptates beatae ea non, natus numquam sint, nam quasi aspernatur aliquam.</p>
  </div>
  <div class="question-container">
    <p class="question">When will I receive my order?</p>
    <p class="answer">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Veniam porro quidem eum praesentium officia voluptas repellendus amet minima alias voluptates beatae ea non, natus numquam sint, nam quasi aspernatur aliquam.</p>
  </div>
  <div class="question-container">
    <p class="question">Where are you located?</p>
    <p class="answer">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Veniam porro quidem eum praesentium officia voluptas repellendus amet minima alias voluptates beatae ea non, natus numquam sint, nam quasi aspernatur aliquam.</p>
  </div>
</div>