/* ========================================
   UAV MTC - Design Tokens
   维修工装风格：深蓝 + 橙色
   ======================================== */
:root {
  --c-primary: #0f1b3d;
  --c-primary-light: #1a2a5e;
  --c-accent: #ff6b2b;
  --c-accent-hover: #e55a1b;
  --c-accent-light: rgba(255, 107, 43, 0.1);
  --c-bg: #ffffff;
  --c-bg-alt: #f5f6fa;
  --c-bg-dark: #0a0f1f;
  --c-text: #1a1a2e;
  --c-text-secondary: #6b7280;
  --c-text-light: #9ca3af;
  --c-border: #e5e7eb;
  --c-card: #ffffff;
  --c-success: #10b981;
  --c-warning: #f59e0b;
  --c-danger: #ef4444;

  --font-display: 'PingFang SC', -apple-system, sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'PingFang SC', sans-serif;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
  --shadow-accent: 0 4px 20px rgba(255,107,43,0.3);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --z-nav: 100;
  --z-modal: 200;
  --z-overlay: 150;

  --container: 1200px;
  --nav-h: 72px;
}

/* ========================================
   Layout
   ======================================== */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section--dark {
  background: var(--c-bg-dark);
  color: #fff;
}

.section--alt {
  background: var(--c-bg-alt);
}

.section__label {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--c-accent);
  margin-bottom: 12px;
}

.section__title {
  font-family: var(--font-display);
  font-size: 36px;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 16px;
}

.section--dark .section__title { color: #fff; }

.section__desc {
  font-size: 17px;
  color: var(--c-text-secondary);
  max-width: 600px;
  line-height: 1.7;
}

.section--dark .section__desc { color: rgba(255,255,255,0.6); }

/* ========================================
   Navigation
   ======================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-h);
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  z-index: var(--z-nav);
  border-bottom: 1px solid var(--c-border);
  transition: background 0.3s, box-shadow 0.3s;
}

.nav.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 20px;
  color: var(--c-primary);
}

.nav__logo svg {
  width: 36px;
  height: 36px;
}

.nav__logo-sub {
  font-size: 11px;
  font-weight: 400;
  color: var(--c-text-secondary);
  margin-left: -4px;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav__link {
  font-size: 15px;
  font-weight: 500;
  color: var(--c-text-secondary);
  transition: color 0.2s;
  position: relative;
}

.nav__link:hover,
.nav__link.active {
  color: var(--c-primary);
}

.nav__link.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--c-accent);
  border-radius: 1px;
}

.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  background: var(--c-accent);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-full);
  transition: background 0.2s, transform 0.15s;
}

.nav__cta:hover {
  background: var(--c-accent-hover);
  transform: translateY(-1px);
}

.nav__burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav__burger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--c-primary);
  border-radius: 1px;
  transition: transform 0.3s;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 15px;
  font-weight: 600;
  padding: 12px 28px;
  border-radius: var(--radius-full);
  transition: all 0.2s;
  white-space: nowrap;
}

.btn--primary {
  background: var(--c-accent);
  color: #fff;
  box-shadow: var(--shadow-accent);
}

.btn--primary:hover {
  background: var(--c-accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(255,107,43,0.4);
}

.btn--outline {
  border: 2px solid var(--c-primary);
  color: var(--c-primary);
  background: transparent;
}

.btn--outline:hover {
  background: var(--c-primary);
  color: #fff;
}

.btn--ghost {
  color: var(--c-accent);
  padding: 8px 0;
}

.btn--ghost:hover {
  color: var(--c-accent-hover);
}

.btn--lg {
  font-size: 17px;
  padding: 16px 36px;
}

.btn--sm {
  font-size: 13px;
  padding: 8px 20px;
}

.btn--dark {
  background: var(--c-primary);
  color: #fff;
}

.btn--dark:hover {
  background: var(--c-primary-light);
}

/* ========================================
   Hero
   ======================================== */
.hero {
  position: relative;
  min-height: calc(100vh - var(--nav-h));
  display: flex;
  align-items: center;
  padding-top: var(--nav-h);
  overflow: hidden;
  background: linear-gradient(135deg, #0a0f1f 0%, #1a2a5e 50%, #0f1b3d 100%);
}

.hero__canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.15;
  pointer-events: none;
}

.hero__content {
  position: relative;
  z-index: 2;
  max-width: 700px;
  padding: 60px 0;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(255,107,43,0.15);
  border: 1px solid rgba(255,107,43,0.3);
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 600;
  color: var(--c-accent);
  margin-bottom: 24px;
}

.hero__badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-accent);
  animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

.hero__title {
  font-family: var(--font-display);
  font-size: 52px;
  font-weight: 900;
  line-height: 1.15;
  color: #fff;
  margin-bottom: 20px;
}

.hero__title span {
  color: var(--c-accent);
}

.hero__subtitle {
  font-size: 20px;
  color: rgba(255,255,255,0.7);
  line-height: 1.7;
  margin-bottom: 12px;
}

.hero__tagline {
  font-size: 15px;
  color: rgba(255,255,255,0.45);
  margin-bottom: 36px;
  font-style: italic;
}

.hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  margin-bottom: 40px;
}

.hero__meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 15px;
  color: rgba(255,255,255,0.8);
}

.hero__meta-item svg {
  width: 18px;
  height: 18px;
  fill: var(--c-accent);
}

.hero__actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero__stats {
  display: flex;
  gap: 48px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid rgba(255,255,255,0.1);
}

.hero__stat-num {
  font-size: 36px;
  font-weight: 800;
  color: var(--c-accent);
  line-height: 1;
}

.hero__stat-label {
  font-size: 13px;
  color: rgba(255,255,255,0.5);
  margin-top: 6px;
}

/* ========================================
   Highlights / Feature Cards
   ======================================== */
.highlights__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.highlight-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  transition: all 0.3s;
  position: relative;
  overflow: hidden;
}

.highlight-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--c-accent);
  transform: scaleX(0);
  transition: transform 0.3s;
}

.highlight-card:hover {
  border-color: transparent;
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}

.highlight-card:hover::before {
  transform: scaleX(1);
}

.highlight-card__icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--c-accent-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.highlight-card__icon svg {
  width: 24px;
  height: 24px;
  fill: var(--c-accent);
}

.highlight-card__title {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--c-primary);
}

.highlight-card__desc {
  font-size: 14px;
  color: var(--c-text-secondary);
  line-height: 1.6;
}

/* ========================================
   Schedule
   ======================================== */
.schedule__tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 32px;
}

.schedule__tab {
  padding: 10px 24px;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-full);
  border: 2px solid var(--c-border);
  color: var(--c-text-secondary);
  transition: all 0.2s;
}

.schedule__tab.active,
.schedule__tab:hover {
  border-color: var(--c-accent);
  color: var(--c-accent);
  background: var(--c-accent-light);
}

.schedule__day {
  display: none;
}

.schedule__day.active {
  display: block;
}

.schedule-item {
  display: flex;
  gap: 20px;
  padding: 20px 0;
  border-bottom: 1px solid var(--c-border);
  align-items: flex-start;
}

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

.schedule-item__time {
  min-width: 100px;
  font-size: 14px;
  font-weight: 700;
  color: var(--c-accent);
  padding-top: 2px;
}

.schedule-item__body h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 4px;
}

.schedule-item__body p {
  font-size: 13px;
  color: var(--c-text-secondary);
}

.schedule-item__tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  margin-left: 8px;
  vertical-align: middle;
}

.schedule-item__tag--workshop { background: #dbeafe; color: #1d4ed8; }
.schedule-item__tag--contest { background: #fef3c7; color: #b45309; }
.schedule-item__tag--share { background: #d1fae5; color: #065f46; }
.schedule-item__tag--social { background: #fce7f3; color: #9d174d; }

/* ========================================
   Speakers
   ======================================== */
.speakers__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.speaker-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: 32px;
  text-align: center;
  transition: all 0.3s;
}

.speaker-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.speaker-card__avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  margin: 0 auto 16px;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  font-weight: 800;
  color: #fff;
}

.speaker-card__name {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 4px;
}

.speaker-card__role {
  font-size: 13px;
  color: var(--c-accent);
  font-weight: 500;
  margin-bottom: 12px;
}

.speaker-card__topic {
  font-size: 14px;
  color: var(--c-text-secondary);
  line-height: 1.5;
}

/* ========================================
   Tickets / Registration
   ======================================== */
.tickets__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.ticket-card {
  background: var(--c-card);
  border: 2px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  text-align: center;
  position: relative;
  transition: all 0.3s;
}

.ticket-card.featured {
  border-color: var(--c-accent);
  box-shadow: var(--shadow-accent);
}

.ticket-card.featured::after {
  content: '热门';
  position: absolute;
  top: 12px;
  right: 12px;
  font-size: 11px;
  font-weight: 700;
  padding: 3px 10px;
  background: var(--c-accent);
  color: #fff;
  border-radius: var(--radius-full);
}

.ticket-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.ticket-card__type {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-text-secondary);
  margin-bottom: 12px;
}

.ticket-card__price {
  font-size: 36px;
  font-weight: 800;
  color: var(--c-primary);
  margin-bottom: 4px;
}

.ticket-card__price small {
  font-size: 14px;
  font-weight: 400;
  color: var(--c-text-secondary);
}

.ticket-card__desc {
  font-size: 13px;
  color: var(--c-text-secondary);
  margin-bottom: 20px;
  line-height: 1.5;
}

.ticket-card__features {
  text-align: left;
  margin-bottom: 24px;
}

.ticket-card__features li {
  font-size: 13px;
  color: var(--c-text-secondary);
  padding: 6px 0;
  display: flex;
  align-items: center;
  gap: 8px;
}

.ticket-card__features li::before {
  content: '';
  width: 16px;
  height: 16px;
  background: var(--c-accent-light);
  border-radius: 50%;
  flex-shrink: 0;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Cpath fill='%23ff6b2b' d='M6.5 11.5l-3-3 1-1 2 2 5-5 1 1z'/%3E%3C/svg%3E");
  background-size: 10px;
  background-position: center;
  background-repeat: no-repeat;
}

/* ========================================
   Testimonials
   ======================================== */
.testimonials__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.testimonial-card {
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-md);
  padding: 28px;
}

.testimonial-card__quote {
  font-size: 15px;
  line-height: 1.7;
  color: rgba(255,255,255,0.8);
  margin-bottom: 16px;
  position: relative;
  padding-left: 20px;
}

.testimonial-card__quote::before {
  content: '"';
  position: absolute;
  left: 0;
  top: -4px;
  font-size: 32px;
  color: var(--c-accent);
  font-weight: 800;
}

.testimonial-card__author {
  font-size: 13px;
  color: rgba(255,255,255,0.5);
}

/* ========================================
   Registration Form
   ======================================== */
.reg-form {
  max-width: 600px;
  margin: 0 auto;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--c-text);
}

.form-group label .required {
  color: var(--c-danger);
}

.form-input {
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  border: 2px solid var(--c-border);
  border-radius: var(--radius-sm);
  transition: border-color 0.2s;
  background: #fff;
}

.form-input:focus {
  outline: none;
  border-color: var(--c-accent);
}

.form-input::placeholder {
  color: var(--c-text-light);
}

.radio-group {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.radio-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  cursor: pointer;
}

.radio-label input[type="radio"] {
  accent-color: var(--c-accent);
  width: 18px;
  height: 18px;
}

.ticket-select {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

.ticket-option {
  padding: 16px;
  border: 2px solid var(--c-border);
  border-radius: var(--radius-sm);
  text-align: center;
  cursor: pointer;
  transition: all 0.2s;
}

.ticket-option:hover,
.ticket-option.selected {
  border-color: var(--c-accent);
  background: var(--c-accent-light);
}

.ticket-option__name {
  font-size: 14px;
  font-weight: 600;
}

.ticket-option__price {
  font-size: 20px;
  font-weight: 800;
  color: var(--c-accent);
  margin-top: 4px;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  background: var(--c-bg-dark);
  color: rgba(255,255,255,0.6);
  padding: 60px 0 30px;
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer__brand {
  font-size: 20px;
  font-weight: 800;
  color: #fff;
  margin-bottom: 12px;
}

.footer__brand-sub {
  font-size: 13px;
  color: rgba(255,255,255,0.4);
  margin-bottom: 16px;
  line-height: 1.6;
}

.footer__col h4 {
  font-size: 14px;
  font-weight: 600;
  color: #fff;
  margin-bottom: 16px;
}

.footer__col a {
  display: block;
  font-size: 13px;
  color: rgba(255,255,255,0.5);
  padding: 4px 0;
  transition: color 0.2s;
}

.footer__col a:hover {
  color: var(--c-accent);
}

.footer__bottom {
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  justify-content: space-between;
  font-size: 12px;
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 1024px) {
  .highlights__grid { grid-template-columns: repeat(2, 1fr); }
  .tickets__grid { grid-template-columns: repeat(2, 1fr); }
  .speakers__grid { grid-template-columns: repeat(2, 1fr); }
  .footer__grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  :root { --nav-h: 60px; }
  
  .section { padding: 56px 0; }
  .section__title { font-size: 28px; }
  
  .nav__links { display: none; }
  .nav__burger { display: flex; }
  .nav__cta { display: none; }
  
  .nav__links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: #fff;
    padding: 16px 24px;
    border-bottom: 1px solid var(--c-border);
    gap: 16px;
  }
  
  .hero { min-height: auto; padding-top: calc(var(--nav-h) + 40px); }
  .hero__content { padding: 0 0 40px; }
  .hero__title { font-size: 32px; }
  .hero__subtitle { font-size: 16px; }
  .hero__meta { gap: 16px; }
  .hero__stats { gap: 24px; flex-wrap: wrap; }
  .hero__stat-num { font-size: 28px; }
  .hero__actions { flex-direction: column; }
  .hero__actions .btn { width: 100%; justify-content: center; }
  
  .highlights__grid { grid-template-columns: 1fr; }
  .speakers__grid { grid-template-columns: 1fr; }
  .tickets__grid { grid-template-columns: 1fr; }
  .testimonials__grid { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; gap: 24px; }
  
  .schedule__tabs { flex-wrap: wrap; }
  .schedule-item { flex-direction: column; gap: 4px; }
  .schedule-item__time { min-width: auto; }
  
  .ticket-select { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .hero__title { font-size: 26px; }
  .btn--lg { font-size: 15px; padding: 14px 28px; }
}