:root {
  --bg-color: #f4f6f8;
  --text-color: #333;
  --card-bg: #fff;
  --btn-bg: #2563eb;
  --btn-hover: #1d4ed8;
  --section-bg: #ffffff;
}

[data-theme="dark"] {
  --bg-color: #0f172a;
  --text-color: #f1f5f9;
  --card-bg: #1e293b;
  --btn-bg: #3b82f6;
  --btn-hover: #60a5fa;
  --section-bg: #1e293b;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
}

.container {
  width: 90%;
  max-width: 1100px;
  margin: auto;
  padding: 2rem 0;
}

.section {
  padding: 4rem 0;
  background: var(--section-bg);
}

h1, h2, h3 {
  margin-bottom: 1rem;
  font-weight: 700;
}

a {
  text-decoration: none;
  color: inherit;
}

.btn-primary {
  background: var(--btn-bg);
  color: white;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s ease;
}

.btn-primary:hover {
  background: var(--btn-hover);
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--card-bg);
  padding: 1rem 2rem;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.navbar a {
  margin-left: 1rem;
  font-weight: 600;
}

.grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.card {
  background: var(--card-bg);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  transition: transform 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
}

.toggle-btn {
  cursor: pointer;
}

/* Animation */
.card {
  animation: fadeInUp 1s ease both;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}