:root {
  --primary-color: #0071E3;
  --secondary-color: #1D1D1F;
  --bg-color: #ffffff;
  --text-color: #171717;
  --accent-bg: #f5f5f7;
  --border-color: #d2d2d7;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

header {
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 5%;
  position: sticky;
  top: 0;
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--secondary-color);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.logo span {
  color: var(--primary-color);
}

nav a {
  color: var(--secondary-color);
  text-decoration: none;
  margin-left: 2rem;
  font-size: 0.95rem;
  font-weight: 500;
  transition: var(--transition);
}

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

main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 4rem 5%;
}

h1, h2, h3, h4 {
  color: var(--secondary-color);
  font-weight: 600;
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
}

h1 { font-size: 3rem; line-height: 1.1; }
h2 { font-size: 2.25rem; }

p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
  color: #424245;
}

.btn {
  display: inline-block;
  background-color: var(--primary-color);
  color: #ffffff;
  padding: 12px 24px;
  border-radius: 980px;
  text-decoration: none;
  font-weight: 500;
  font-size: 1rem;
  transition: var(--transition);
  border: none;
  cursor: pointer;
}

.btn:hover {
  background-color: #0077ED;
  transform: scale(1.02);
  opacity: 0.9;
}

.btn-secondary {
  background-color: var(--secondary-color);
}

.card {
  background-color: var(--accent-bg);
  border-radius: 18px;
  padding: 2rem;
  margin-bottom: 2rem;
  transition: var(--transition);
  border: 1px solid transparent;
}

.card:hover {
  border-color: var(--border-color);
  transform: translateY(-4px);
}

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  text-decoration: underline;
}

.guide-meta {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--primary-color);
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

footer {
  background-color: var(--accent-bg);
  padding: 4rem 5%;
  margin-top: 4rem;
  border-top: 1px solid var(--border-color);
  color: #6e6e73;
  font-size: 0.85rem;
}

@media (max-width: 768px) {
  h1 { font-size: 2.5rem; }
  header { flex-direction: column; gap: 1rem; }
  nav a { margin: 0 1rem; }
}