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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: #333;
  background: #f5f5f5;
}

/* Header */
header.header {
  position: fixed;
  width: 100%;
  top: 0;
  left: 0;
  background: #fff;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 40px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  z-index: 1000;
}

header .logo {
  font-weight: bold;
  font-size: 24px;
}

header nav a {
  margin-left: 20px;
  text-decoration: none;
  color: #007bff;
  font-weight: 500;
}

header nav a:hover {
  text-decoration: underline;
}

header .btn-login {
  padding: 8px 16px;
  background-color: #007bff;
  color: #fff;
  border-radius: 6px;
  transition: background 0.3s;
}

header .btn-login:hover {
  background-color: #0056b3;
}

/* Sections */
section {
  padding: 120px 20px 80px; /* 上方留給固定 header */
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  text-align: center;
}

section.section-alt {
  background: #e8f0fe;
}

.hero {
  background: linear-gradient(to bottom right, #007bff, #00c6ff);
  color: white;
  padding-top: 160px;
}

.hero h1 {
  font-size: 48px;
  margin-bottom: 20px;
}

.hero p {
  font-size: 20px;
  margin-bottom: 30px;
}

.hero .btn-login {
  background-color: #fff;
  color: #007bff;
  font-weight: bold;
}

.hero .btn-login:hover {
  background-color: #f0f0f0;
}

.section-content {
  max-width: 800px;
  margin: 0 auto;
}

.features-list {
  list-style: none;
  margin-top: 20px;
}

.features-list li {
  margin-bottom: 15px;
  font-size: 18px;
}

/* Footer */
footer.footer {
  text-align: center;
  padding: 20px;
  background: #f8f8f8;
  color: #666;
}

/* Smooth scroll */
html {
  scroll-behavior: smooth;
}

/* Responsive */
@media (max-width: 768px) {
  header.header {
    flex-direction: column;
    gap: 10px;
    padding: 15px 20px;
  }
  header nav a {
    margin-left: 0;
    margin-right: 10px;
  }

  .hero h1 {
    font-size: 32px;
  }

  .hero p {
    font-size: 16px;
  }
}