:root {
   --bg-color: #f2f2f2; /* light background */
   --text-color: #222;
   --card-color: #ffffff;
   --header-bg: #1D3C6B; /* dark blue */
   --footer-bg: #1D3C6B; /* dark blue */
   --nav-bg: #0C1A36; /* deep blue */
   --link-color: #7EC8E3; /* baby blue */
   --link-hover: #5BA9D0; /* hover baby blue */
}

body.dark-mode {
   --bg-color: #121212;
   --text-color: #e0e0e0;
   --card-color: #1f1f1f;
   --header-bg: #0C1A36; /* deep blue */
   --footer-bg: #0C1A36; /* deep blue */
   --nav-bg: #0C1A36; /* dark blue */
   --link-color: #A2D4E6; /* baby blue */
   --link-hover: #8CC0D7; /* hover baby blue */
}

body {
   font-family: Arial, sans-serif;
   background-color: var(--bg-color);
   color: var(--text-color);
   margin: 0;
   padding: 0;
   transition: all 0.3s ease;
}

header {
   background-color: var(--header-bg);
   color: white;
   text-align: center;
   padding: 2rem 1rem;
   position: relative;
}

#theme-toggle {
   position: absolute;
   top: 20px;
   right: 20px;
   padding: 8px 12px;
   background-color: white;
   color: black;
   border: none;
   border-radius: 4px;
   cursor: pointer;
}

body.dark-mode #theme-toggle {
   background-color: #2c2c2c;
   color: white;
}

nav {
   background-color: var(--nav-bg);
   padding: 0.5rem;
   text-align: center;
}

nav ul {
   list-style: none;
   padding: 0;
   margin: 0;
}

nav ul li {
   display: inline;
   margin: 0 1rem;
}

nav ul li a {
   color: white;
   text-decoration: none;
   font-weight: bold;
}

.card {
   background-color: var(--card-color);
   margin: 2rem auto;
   padding: 1.5rem;
   border-radius: 8px;
   max-width: 800px;
   box-shadow: 0 0 10px rgba(0, 0, 0, 0.05);
}

.card a {
   color: var(--link-color);
   text-decoration: none;
   font-weight: bold;
}

.card a:hover {
   text-decoration: underline;
   color: var(--link-hover);
}

.card img {
   vertical-align: middle;
   margin-right: 8px;
}

h2 {
   border-bottom: 1px solid #ccc;
   padding-bottom: 0.5rem;
}

footer {
   text-align: center;
   padding: 1rem;
   background-color: var(--footer-bg);
   color: white;
}