* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.6;
  background-color: #f4f7fb;
  color: #1f2937;
}

header {
  background-color: #0f172a;
  color: white;
  padding: 24px 0;
}

.container {
  width: 90%;
  max-width: 1000px;
  margin: 0 auto;
}

header h1 {
  margin: 0;
  font-size: 2rem;
}

header p {
  margin: 8px 0 0;
}

nav {
  background-color: #1e3a8a;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
}

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

nav li {
  margin: 0;
}

nav a {
  display: block;
  color: white;
  text-decoration: none;
  padding: 14px 18px;
}

nav a:hover {
  background-color: #2563eb;
}

#theme-toggle {
  background-color: white;
  color: #1e3a8a;
  border: none;
  padding: 10px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-weight: bold;
  margin: 8px 0;
}

#theme-toggle:hover {
  background-color: #dbeafe;
}

main {
  padding: 30px 0;
}

section,
.card {
  background: white;
  margin-bottom: 20px;
  padding: 22px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

h2 {
  color: #1e3a8a;
  margin-top: 0;
}

ul {
  padding-left: 20px;
}

footer {
  background-color: #0f172a;
  color: white;
  text-align: center;
  padding: 15px 0;
  margin-top: 30px;
}

.hero {
  padding: 10px 0;
}

.hero-text {
  background: white;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.button-link {
  display: inline-block;
  margin-top: 12px;
  background-color: #1e3a8a;
  color: white;
  text-decoration: none;
  padding: 10px 16px;
  border-radius: 6px;
}

.button-link:hover {
  background-color: #2563eb;
}

body.dark-mode {
  background-color: #0b1120;
  color: #e5e7eb;
}

body.dark-mode header {
  background-color: #020617;
}

body.dark-mode nav {
  background-color: #111827;
}

body.dark-mode section,
body.dark-mode .card,
body.dark-mode .hero-text {
  background-color: #1f2937;
  color: #e5e7eb;
}

body.dark-mode h2 {
  color: #93c5fd;
}

body.dark-mode footer {
  background-color: #020617;
}

body.dark-mode #theme-toggle {
  background-color: #334155;
  color: white;
}

@media (max-width: 700px) {
  header h1 {
    font-size: 1.5rem;
  }

  nav ul {
    flex-direction: column;
    width: 100%;
  }

  .nav-container {
    align-items: flex-start;
  }

  nav a {
    padding: 12px 14px;
  }
}