How to make images responsive on smaller screen sizes?

const resultsNav = document.getElementById("resultsNav");
const favoritesNav = document.getElementById("favoritesNav");
const imagesContainer = document.querySelector(".images-container");
const saveConfirmed = document.querySelector(".save-confirmed");
const loader = document.querySelector(".loader");

// NASA API
const count = 18;
const apiKey = 'DEMO_KEY';
const apiUrl = `https://api.nasa.gov/planetary/apod?api_key=${apiKey}&count=${count}`;

let resultsArray = [];
let favorites = {};

// Show Content
function showContent(page) {
  window.scrollTo({ top: 0, behavior: "instant" });
  if (page === "results") {
    resultsNav.classList.remove("hidden");
    favoritesNav.classList.add("hidden");
  } else {
    resultsNav.classList.add("hidden");
    favoritesNav.classList.remove("hidden");
  }
  loader.classList.add("hidden");
}

// Create DOM Nodes
function createDOMNodes(page) {
  const currentArray =
    page === "results" ? resultsArray : Object.values(favorites);
  currentArray.forEach((result) => {
    // Card Container
    const card = document.createElement("div");
    card.classList.add("card");

    // Link that wraps the image
    const link = document.createElement("a");
    link.href = result.hdurl;
    link.title = "View Full Image";
    link.target = "_blank";

    // Image
    const image = document.createElement("img");
    image.src = result.url;
    image.alt = "NASA Picture of the Day";
    image.loading = "lazy";
    image.classList.add("card-img-top");

    // Card Body
    const cardBody = document.createElement("div");
    cardBody.classList.add("card-body");

    // Card Title
    const cardTitle = document.createElement("h5");
    cardTitle.classList.add("card-title");
    cardTitle.textContent = result.title;

    // Save Text
    const saveText = document.createElement("p");
    saveText.classList.add("clickable");
    if (page === "results") {
      saveText.textContent = "Add To Favorites";
      saveText.setAttribute("onclick", `saveFavorite('${result.url}')`);
    } else {
      saveText.textContent = "Remove Favorite";
      saveText.setAttribute("onclick", `removeFavorite('${result.url}')`);
    }

    // Card Text
    const cardText = document.createElement("p");
    cardText.textContent = result.explanation;

    // Footer Conatiner
    const footer = document.createElement("small");
    footer.classList.add("text-muted");

    // Date
    const date = document.createElement("strong");
    date.textContent = result.date;

    // Copyright
    const copyrightResult =
      result.copyright === undefined ? "" : result.copyright;
    const copyright = document.createElement("span");
    copyright.textContent = ` ${copyrightResult}`;

    // Append everything together
    footer.append(date, copyright);
    // cardBody.append(cardTitle, saveText, cardText, footer); //hide to make image display
    link.appendChild(image);
    card.append(link);

    // Append to image container
    imagesContainer.appendChild(card);
  });
}

// Update the DOM
function updateDOM(page) {
  // Get favorites from local storage
  if (localStorage.getItem("nasaFavorites")) {
    favorites = JSON.parse(localStorage.getItem("nasaFavorites"));
  }
  imagesContainer.textContent = "";
  createDOMNodes(page);
  showContent(page);
}

// Get 10 images from NASA API
async function getNasaPictures() {
  // Show Loader
  loader.classList.remove("hidden");
  try {
    const response = await fetch(apiUrl);
    resultsArray = await response.json();
    updateDOM("results");
  } catch (error) {
    // Catch Error Here
  }
}

// Add result to favorites
function saveFavorite(itemUrl) {
  // Loop through the results array to seelct favorite
  resultsArray.forEach((item) => {
    if (item.url.includes(itemUrl) && !favorites[itemUrl]) {
      favorites[itemUrl] = item;
      // Show save confirmation for 2 seconds
      saveConfirmed.hidden = false;
      setTimeout(() => {
        saveConfirmed.hidden = true;
      }, 2000);
      // Set Favorites in Local Storage
      localStorage.setItem("nasaFavorites", JSON.stringify(favorites));
    }
  });
}

// Remove item from favorites
function removeFavorite(itemUrl) {
  if (favorites[itemUrl]) {
    delete favorites[itemUrl];
    localStorage.setItem("nasaFavorites", JSON.stringify(favorites));
    updateDOM("favorites");
  }
}

// On Load
getNasaPictures();

html {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: whitesmoke;
  overflow-x: hidden;
  font-family: Verdana, sans-serif;
  font-size: 1rem;
  line-height: 1.8rem;
}

.container {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 5px;
  margin-bottom: 25px;
}

/* Navigation */
.navigation-container {
  position: fixed;
  top: 0;
}

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

.background {
  background: whitesmoke;
  position: fixed;
  right: 0;
  width: 100%;
  height: 60px;
  z-index: -1;
}

.clickable {
  color: #0b3d91;
  cursor: pointer;
  user-select: none;
}

.clickable:hover {
  color: #fc3d21;
}

/* Images Container */
.images-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding-top: 100px;
}

.column {
  margin-left: auto;
  margin-right: auto;
}

.card {
  margin: 10px 10px 20px;
  width: 300px;
  height: 300px;
}

.card-img-top {
  width: 300px;
  height: 300px;
  border-radius: 5px 5px 0 0;
  display: block;
  margin-left: auto;
  margin-right: auto;
}

.card-body {
  padding: 20px;
}

.card-title {
  margin: 10px auto;
  font-size: 24px;
}

/* Save Confirmation */
.save-confirmed {
  background: white;
  padding: 8px 16px;
  border-radius: 5px;
  box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2);
  transition: 0.3s;
  position: fixed;
  bottom: 25px;
  right: 50px;
  z-index: 500;
}

/* Hidden */
.hidden {
  display: none;
}

<div class="loader hidden">
    </div>

    <!-- Container -->
    <div class="container">
      <!-- Navigation -->
      <div class="navigation-container">
        <span class="background"></span>
        <!-- Results Nav -->
        <span class="navigation-items" id="resultsNav">
          <h3 class="clickable" onclick="updateDOM('favorites')">Favorites</h3>
          <h3>&nbsp;&nbsp;&nbsp;•&nbsp;&nbsp;&nbsp;</h3>
          <h3 class="clickable" onclick="getNasaPictures()">Load More</h3>
        </span>
        <!-- Favorites Nav -->
        <span class="navigation-items hidden" id="favoritesNav">
          <h3 class="clickable" onclick="getNasaPictures()">
            Load More NASA Images
          </h3>
        </span>
      </div>

      <!-- Images Container -->
      <div class="container-fluid">
        <div class="row">
          <div class="column">
            <div class="images-container"></div>
          </div>
        </div>
      </div>
    </div>

    <!-- Save Confirmation -->
    <div class="save-confirmed" hidden>
      <h1>ADDED!</h1>
    </div>