:root {
  --bg: #f9fafb;
  --text: #111827;
  --card: #ffffff;
  --border: #e5e7eb;
  --accent: #2563eb;
}

[data-theme="dark"] {
  --bg: #0f172a;
  --text: #e5e7eb;
  --card: #020617;
  --border: #1e293b;
  --accent: #38bdf8;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, sans-serif;
  margin: 0;
}

h1 { font-size: clamp(2rem, 4vw, 3rem); }
h2 { font-size: clamp(2.2rem, 3vw, 3.0rem); }
h3 { font-size: 1.6rem; }


p {
font-size: 1.15rem;
line-height: 1.7;
color: var(--muted);
}

nav a {
margin-left: 24px;
text-decoration: none;
font-weight: 600;
color: var(--text);
}


nav a:hover { color: var(--accent); }

button {
padding: 10px 18px;
border-radius: 8px;
border: none;
font-weight: 600;
cursor: pointer;
}


.theme-btn {
  background: var(--accent);
  color: black;
  border-radius: 10px;
  padding: 10px 16px;
  margin-left: 16px;
}

.theme-btn:hover {
  opacity: 0.9;
}
.hero {
padding: 10px 40px;
max-width: 1100px;
margin: auto;
}


.section {
padding: 50px 40px;
max-width: 1100px;
margin: auto;
}


header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 32px;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.08);
}

footer {
padding: 60px 40px;
text-align: center;
border-top: 1px solid var(--border);
}