* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
}

body {
  min-height: 100vh;
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: #0f1117;
  color: #f3f4f6;
  line-height: 1.7;

  display: flex;
  flex-direction: column;
}

header {
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  padding: 48px 20px;
  text-align: center;
}

header h1 {
  margin: 0;
  font-size: 2.3rem;
}

header p {
  margin: 10px 0 0;
  color: #e5e7eb;
}

nav {
  background: #161a24;
  border-bottom: 1px solid #2d3444;
  padding: 14px 20px;
  text-align: center;
}

nav a {
  color: #dbeafe;
  text-decoration: none;
  margin: 0 12px;
  font-weight: 700;
}

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

main {
  width: 100%;
  max-width: 900px;
  margin: 32px auto;
  padding: 0 20px 40px;

  flex: 1;
}

.card {
  background: #161a24;
  border: 1px solid #2d3444;
  border-radius: 16px;
  padding: 28px;
  box-shadow: 0 10px 30px rgba(0,0,0,.25);
}

h2 {
  margin-top: 28px;
  color: #bfdbfe;
}

h2:first-child {
  margin-top: 0;
}

ul {
  padding-left: 24px;
}

a {
  color: #93c5fd;
}

.notice {
  background: #111827;
  border-left: 4px solid #60a5fa;
  padding: 14px 16px;
  border-radius: 8px;
  color: #d1d5db;
}

footer {
  border-top: 1px solid #2d3444;
  color: #9ca3af;
  text-align: center;
  padding: 24px 20px;
  background: #0b0d12;
}

@media (max-width: 600px) {
  header h1 {
    font-size: 1.7rem;
  }

  nav a {
    display: block;
    margin: 8px 0;
  }

  .card {
    padding: 20px;
  }
}