Refactor: Modularized footer.njk and header-footer.css

- Split header-footer.css into:
    - header.css
    - footer.css
    - modals.css
- Split footer.njk into:
    - footer.njk
    - modals.njk
- Updated front matter of:
    - index.njk
    - about.njk
    - credits.njk
    - gallery.njk
    - community.njk

src/styles/footer.css

@@ -0,0 +1,139 @@
+nav ul, #footer-nav ul {
+    display: flex;
+    justify-content: center;
+    list-style: none;
+    padding: 0;
+    margin: 0;
+}
+
+#footer-nav ul {
+    position: relative;
+    list-style-type: none;
+    flex-direction: row;
+    margin-top: 20px;
+    background-color: var(--color-destin-sand);
+    border-radius: 5px;
+    width: fit-content; 
+    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+}
+
+nav ul li, #footer-nav ul li {
+    margin: 0 20px;
+    border-radius: 5px;
+}
+
+nav ul li a, #footer-nav ul li a {
+    font-family: 'Arial', sans-serif;
+    font-size: 1rem;
+    font-weight: bold;
+    color: var(--color-dark-green); 
+    text-decoration: underline;
+    padding: 8px 15px;
+    border-radius: 10px;
+    transition: background-color 0.3s ease, color 0.3s ease;
+}
+
+nav ul li a:hover, #footer-nav ul li a:hover {
+    background-color: var(--color-destin-sand);
+    color: var(--color-dark-green);
+    border: solid .5px var(--color-dark-green);
+    padding: 7px 14px;
+    box-shadow: var(--shadow-medium);
+}
+
+/* |--↓-↓-↓ Start Footer ↓-↓-↓--| */
+#footer {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    text-align: center;
+}
+
+#newsletter-container {
+    display: inline-block;
+    margin-bottom: 10px;
+    text-align: center;
+}
+
+#email-input {
+    display: inline-block;
+    width: 55%;
+    padding: 5px 10px;
+    text-align: center;
+    border-radius: 10px;
+    box-shadow: var(--shadow-subtle);
+}
+
+button#submit-btn {
+    display: inline-block;
+    padding: 5px 10px;
+    border-radius: 10px;
+    cursor: pointer;
+    box-shadow: var(--shadow-subtle);
+    z-index: 5;
+}
+
+footer div label {
+    font-size: 1.2rem;
+    font-weight: bold;
+    color: var(--color-dark-green);
+}
+
+#newsletter-form {
+    display: inline-block;
+    background-color: var(--color-soft-golden);
+    border: solid var(--color-destin-sand);
+    border-radius: 10px;
+    width: 60%;
+    padding: 5px;
+    text-align: center;
+    box-shadow: var(--shadow-medium);
+}
+
+#social-media {
+    position: relative;
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    text-align: center;
+}
+
+#social-media h3 {
+    text-align: center;
+}
+
+#social-media ul {
+    position: relative;
+    display: inline-block;
+    list-style-type: none;
+    text-align: center;
+}
+
+#social-media ul li {
+    display: inline-block;
+    margin: 0 10px;
+    padding: 0 10px;
+    color: var(--color-dark-green);
+}
+
+#social-media ul li a {
+    font-family: 'Arial', sans-serif;
+    font-size: 1rem;
+    color: var(--color-dark-green);
+    text-decoration: none;
+    padding: 8px 15px;
+    border-radius: 5px;
+    transition: background-color 0.3s ease, color 0.3s ease;
+}
+
+#social-media ul li a:hover {
+    background-color: var(--color-soft-golden);
+    color: var(--color-destin-sand);
+    box-shadow: var(--shadow-strong);
+}
+
+#copyright {
+    text-align: center;
+    margin-bottom: 20px;
+}