:root {
  --bg-color: #0d1117;
  --surface-color: #161b22;
  --accent-color: #bb86fc;
  --text-color: #c9d1d9;
  --text-bright: #ffffff;
  --primary: #388bfd;
}

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

html {
  scroll-padding-top: 3rem;
  scroll-behavior: smooth;
}

body {
  font-family:
    'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans',
    Meiryo, sans-serif;
  background:
    radial-gradient(
      circle at 80% 20%,
      rgba(90, 60, 185, 0.15),
      transparent 40%
    ),
    radial-gradient(
      circle at 20% 80%,
      rgba(137, 87, 229, 0.1),
      transparent 45%
    ),
    var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
}

header {
  background: linear-gradient(135deg, #1f1a3a 0%, #0d1117 100%);
  padding: 60px 20px;
  text-align: center;
  border-bottom: 2px solid #21262d;
}

.header-logo {
  max-width: 150px;
  margin-bottom: 20px;
}

h1 {
  color: var(--text-bright);
  font-size: 2.5rem;
  margin-bottom: 10px;
}

.subtitle {
  color: var(--accent-color);
  font-size: 1.2rem;
  font-weight: bold;
}

nav {
  background-color: var(--surface-color);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid #21262d;
  overflow-x: auto;
  white-space: nowrap;
}

nav ul {
  display: flex;
  justify-content: center;
  list-style: none;
  max-width: 1200px;
  margin: 0 auto;
  padding: 10px;
}

nav a {
  color: var(--text-color);
  text-decoration: none;
  padding: 10px 15px;
  font-weight: bold;
  font-size: 0.9rem;
  transition: color 0.3s;
}

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

main {
  max-width: 1000px;
  margin: 40px auto;
  padding: 0 20px;
}

section {
  background-color: var(--surface-color);
  padding: 40px;
  border-radius: 12px;
  margin-bottom: 40px;
  border: 1px solid #21262d;
}

h2 {
  color: var(--text-bright);
  border-left: 5px solid var(--accent-color);
  padding-left: 15px;
  margin-bottom: 25px;
  font-size: 1.8rem;
}

h3 {
  color: var(--text-bright);
  margin: 20px 0 10px 0;
  font-size: 1.3rem;
}

p {
  margin-bottom: 15px;
}

.program-card {
  background-color: #1f242c;
  padding: 25px;
  border-radius: 8px;
  margin-bottom: 20px;
  border-left: 4px solid var(--primary);
}

.sponsor-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

@media (max-width: 768px) {
  .sponsor-grid {
    grid-template-columns: 1fr;
  }
  section {
    padding: 20px;
  }
}

.sponsor-card {
  background-color: #1f242c;
  padding: 20px;
  border-radius: 8px;
  text-align: center;
}

.section-img {
  width: 100%;
  max-height: 300px;
  object-fit: cover;
  border-radius: 8px;
  margin-bottom: 20px;
}

/* タイムラインのスタイル */
.timeline-container {
  background: linear-gradient(145deg, #1b162b, #161b22);
  border: 2px solid var(--accent-color);
}

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

.timeline-item {
  align-items: center;
  padding: 15px;
  border-bottom: 1px solid #21262d;
  font-size: 1.1rem;
}

.timeline-item:last-child {
  border-bottom: none;
}

.timeline-time {
  font-weight: bold;
  color: var(--accent-color);
  min-width: 130px;
}

.timeline-name {
  color: var(--text-bright);
  font-weight: bold;
}

/* お問い合わせフォーム */
.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 5px;
  color: var(--text-bright);
}

input,
textarea {
  width: 100%;
  padding: 12px;
  background-color: #0d1117;
  border: 1px solid #21262d;
  border-radius: 6px;
  color: var(--text-color);
  font-size: 1rem;
}

input:focus,
textarea:focus {
  border-color: var(--accent-color);
  outline: none;
}

button {
  background-color: var(--accent-color);
  color: #000;
  border: none;
  padding: 12px 30px;
  font-size: 1rem;
  font-weight: bold;
  border-radius: 6px;
  cursor: pointer;
  transition: opacity 0.3s;
}

button:disabled {
  background-color: revert;
  cursor: revert;
}

button:hover {
  opacity: 0.9;
}

/* ダミープレイヤー */
.player-box {
  background: #21262d;
  padding: 15px;
  border-radius: 30px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  flex-direction: column;
}

.player-btn {
  background: var(--accent-color);
  border: none;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  cursor: pointer;
  font-weight: bold;
}

footer {
  text-align: center;
  padding: 40px;
  border-top: 1px solid #21262d;
  font-size: 0.9rem;
}

a {
  color: var(--accent-color);
  text-decoration: none;
}