body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial;
  background: #fff;
  color: #111;
  line-height: 1.7;
}

/* NAV */
nav {
  display: flex;
  justify-content: space-between;
  padding: 30px 60px;
  font-size: 14px;
}

nav a {
  margin-left: 20px;
  text-decoration: none;
  color: #111;
  opacity: 0.5;
  transition: 0.2s;
}

nav a:hover {
  opacity: 1;
}

/* HERO */
.hero {
  padding: 180px 20px 120px;
  text-align: center;
}

h1 {
  font-size: 64px;
  font-weight: 500;
  letter-spacing: -1px;
}

p {
  max-width: 520px;
  margin: 10px auto;
  color: #666;
}

/* SECTION */
.block {
  max-width: 900px;
  margin: auto;
  padding: 100px 20px;
}

h2 {
  font-size: 20px;
  font-weight: 500;
  margin-bottom: 30px;
}

/* GRID */
.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.card {
  padding: 18px;
  border: 1px solid #eee;
  border-radius: 14px;
  transition: 0.3s;
  background: #fafafa;
}

.card:hover {
  transform: translateY(-6px);
}

/* FEATURE SECTION（解决空） */
.feature {
  padding: 160px 20px;
  text-align: center;
  background: #fafafa;
}

.big-text {
  font-size: 42px;
  font-weight: 500;
  letter-spacing: -1px;
  opacity: 0.9;
}

/* BUTTON */
.btn {
  display: inline-block;
  padding: 12px 18px;
  background: #111;
  color: #fff;
  text-decoration: none;
  border-radius: 10px;
}

/* FOOTER */
footer {
  text-align: center;
  padding: 100px 20px 60px;
  color: #aaa;
}

/* ===== SCROLL ANIMATION ===== */

.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: all 0.8s ease;
}

.reveal.show {
  opacity: 1;
  transform: translateY(0);
}

/* MOBILE */
@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 42px;
  }

  nav {
    padding: 20px;
  }
}