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

:root {
  --black: #111111;
  --white: #ffffff;
  --gray: #888888;
  --light: #f5f5f5;
  --border: #e0e0e0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  background: var(--white);
  color: var(--black);
  font-size: 16px;
  line-height: 1.6;
}

/* Header */

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--white);
  z-index: 100;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: -0.01em;
}

.logo-img {
  width: 28px;
  height: 28px;
  object-fit: contain;
  border-radius: 4px;
}

nav {
  display: flex;
  gap: 2rem;
}

nav a {
  color: var(--black);
  text-decoration: none;
  font-size: 0.9rem;
  letter-spacing: 0.02em;
  position: relative;
  transition: color 0.2s;
}

nav a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--black);
  transition: width 0.25s ease;
}

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

nav a:hover::after {
  width: 100%;
}

/* Sections */

main {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 2rem;
}

section {
  padding: 5rem 0;
  border-bottom: 1px solid var(--border);
}

section:last-child {
  border-bottom: none;
}

/* Hero */

.hero {
  padding: 7rem 0;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1.25rem;
  animation: fadeUp 0.7s ease both;
}

.hero p {
  font-size: 1.15rem;
  color: var(--gray);
  max-width: 480px;
  animation: fadeUp 0.7s 0.15s ease both;
}

/* Typography */

h2 {
  font-size: 1.6rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

p {
  color: #444;
  max-width: 600px;
}

.section-sub {
  color: var(--gray);
  margin-bottom: 2rem;
}

/* Grid */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.card {
  border: 1px solid var(--border);
  padding: 1.75rem;
  border-radius: 4px;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.07);
  border-color: #ccc;
}

.card.placeholder {
  background: var(--light);
}

.card p {
  font-size: 0.95rem;
  margin-top: 0.25rem;
}

/* Button */

.btn {
  display: inline-block;
  margin-top: 1.5rem;
  padding: 0.75rem 1.5rem;
  background: var(--black);
  color: var(--white);
  text-decoration: none;
  font-size: 0.9rem;
  border-radius: 4px;
  letter-spacing: 0.01em;
  transition: background 0.2s, transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  background: #333;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.15);
}

.btn:active {
  transform: translateY(0);
  box-shadow: none;
}

/* Footer */

footer {
  padding: 2rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--gray);
  border-top: 1px solid var(--border);
}

/* Animations */

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Mobile */

@media (max-width: 600px) {
  header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  nav {
    gap: 1.25rem;
  }

  .hero {
    padding: 4rem 0;
  }
}