* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: -apple-system, "Microsoft YaHei", sans-serif;
  background: #f5f5f5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

header {
  background: linear-gradient(135deg, #1a237e, #3949ab);
  color: #fff;
  padding: 20px;
  text-align: center;
  position: sticky;
  top: 0;
  z-index: 10;
}
header h1 {
  font-size: 20px;
  letter-spacing: 2px;
}

/* 活动列表 */
.activity-list {
  padding: 16px;
}
.loading {
  text-align: center;
  color: #999;
  padding: 40px;
}
.activity-card {
  background: #fff;
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.activity-card h3 {
  font-size: 17px;
  color: #333;
  margin-bottom: 8px;
}
.activity-card .meta {
  font-size: 13px;
  color: #999;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.activity-card .btn-detail {
  display: inline-block;
  background: #1a237e;
  color: #fff;
  border: none;
  border-radius: 20px;
  padding: 8px 24px;
  font-size: 14px;
  cursor: pointer;
}
.activity-card .btn-detail:active { opacity: 0.8; }
.empty-text {
  text-align: center;
  color: #999;
  padding: 60px 20px;
  font-size: 16px;
}

/* 详情页 */
.detail-page {
  padding: 16px;
}
.btn-back {
  background: none;
  border: none;
  color: #1a237e;
  font-size: 16px;
  cursor: pointer;
  margin-bottom: 12px;
}
.detail-card {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
}
.detail-card h2 {
  font-size: 20px;
  margin-bottom: 12px;
}
.detail-meta {
  margin-bottom: 16px;
}
.detail-meta p {
  font-size: 14px;
  color: #666;
  margin-bottom: 4px;
}
.detail-desc {
  font-size: 15px;
  color: #444;
  line-height: 1.6;
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid #eee;
}

.signup-form h3 {
  font-size: 17px;
  margin-bottom: 12px;
}
.signup-form input {
  display: block;
  width: 100%;
  height: 44px;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 0 12px;
  font-size: 16px;
  margin-bottom: 12px;
  outline: none;
}
.signup-form input:focus { border-color: #1a237e; }
.btn-signup {
  width: 100%;
  height: 44px;
  background: #1a237e;
  color: #fff;
  border: none;
  border-radius: 22px;
  font-size: 16px;
  cursor: pointer;
}
.btn-signup:active { opacity: 0.8; }

/* 成功页 */
.success-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 60px);
  padding: 20px;
}
.success-card {
  background: #fff;
  border-radius: 16px;
  padding: 40px;
  text-align: center;
  width: 100%;
  max-width: 340px;
}
.success-icon { font-size: 60px; margin-bottom: 12px; }
.success-card h2 { font-size: 22px; margin-bottom: 8px; }
.success-card p { color: #666; margin-bottom: 20px; }
.btn-back-list {
  background: #1a237e;
  color: #fff;
  border: none;
  border-radius: 20px;
  padding: 10px 32px;
  font-size: 15px;
  cursor: pointer;
}

/* Toast */
.toast {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(0,0,0,0.75);
  color: #fff;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 15px;
  z-index: 100;
}