body {
  font-family: "Arial", sans-serif;
  margin: 0;
  padding: 0;
  background-color: #0a0a0a;
  color: #eee;
}

header, footer {
  background-color: #111;
  text-align: center;
  padding: 1rem 0;
}

nav a {
  color: #eee;
  margin: 0 1rem;
  text-decoration: none;
}

nav a:hover {
  color: #1e90ff;
}

main {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 1rem;
}

h1, h2, h3 {
  color: #1e90ff;
}

button {
  background-color: #1e90ff;
  border: none;
  padding: 0.5rem 1rem;
  color: #fff;
  cursor: pointer;
  border-radius: 4px;
}

button:hover {
  background-color: #0f7dcf;
}

.koukai{
  color: #1e90ff;
}

/* ロード画面用 */
#loader {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #111;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
}

#loader .loader-inner {
  text-align: center;
  animation: fadeInOut 1s infinite alternate;
}

@keyframes fadeInOut {
  0% { opacity: 0.5; }
  100% { opacity: 1; }
}

/* コンテンツ非表示 */
#content {
  display: none;
}