/* ==========================================================================
   Xiaozhi AI-IoT Vietnam - MiniGame Landing Page
   Design System + Styles
   ========================================================================== */

/* Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;500;600;700;800;900&family=Be+Vietnam+Pro:wght@300;400;500;600;700;800&display=swap');

/* ==========================================================================
   CSS Variables - Design System
   ========================================================================== */
:root {
  /* Background Colors */
  --bg-primary: #0a0a1a;
  --bg-secondary: #1a0a2e;
  --bg-tertiary: #0a1a2e;
  --bg-card: rgba(26, 10, 46, 0.7);
  --bg-card-hover: rgba(26, 10, 46, 0.9);

  /* Neon Colors */
  --neon-pink: #ff007f;
  --neon-pink-light: #ff1493;
  --neon-pink-dark: #cc0066;
  --neon-purple: #9d00ff;
  --neon-purple-light: #b84dff;
  --neon-purple-dark: #7b2cbf;
  --neon-blue: #00d9ff;
  --neon-blue-light: #33e1ff;
  --neon-blue-dark: #0099cc;
  --neon-cyan: #00ffff;

  /* Accent Colors */
  --gold: #ffa500;
  --gold-light: #ffcc00;
  --gold-dark: #cc8400;
  --red: #ff3333;
  --green: #00ff88;

  /* Text Colors */
  --text-primary: #ffffff;
  --text-secondary: rgba(255, 255, 255, 0.85);
  --text-muted: rgba(255, 255, 255, 0.6);
  --text-dark: #1a1a2e;

  /* Gradients */
  --gradient-title: linear-gradient(90deg, #ff007f 0%, #ff8c00 50%, #ffcc00 100%);
  --gradient-bg: linear-gradient(135deg, #0a0a1a 0%, #1a0a2e 30%, #0a1a2e 70%, #0a0a1a 100%);
  --gradient-card: linear-gradient(145deg, rgba(157, 0, 255, 0.15), rgba(0, 217, 255, 0.1));
  --gradient-button: linear-gradient(90deg, #ff007f, #9d00ff);
  --gradient-button-hover: linear-gradient(90deg, #ff1493, #b84dff);
  --gradient-neon-line: linear-gradient(90deg, transparent, #ff007f, #9d00ff, #00d9ff, transparent);

  /* Glow Effects */
  --glow-pink: 0 0 20px rgba(255, 0, 127, 0.6), 0 0 40px rgba(255, 0, 127, 0.3);
  --glow-blue: 0 0 20px rgba(0, 217, 255, 0.6), 0 0 40px rgba(0, 217, 255, 0.3);
  --glow-purple: 0 0 20px rgba(157, 0, 255, 0.6), 0 0 40px rgba(157, 0, 255, 0.3);
  --glow-gold: 0 0 20px rgba(255, 165, 0, 0.6), 0 0 40px rgba(255, 165, 0, 0.3);

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 30px;
  --radius-full: 50%;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
  --transition-bounce: 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);

  /* Font Families */
  --font-display: 'Orbitron', sans-serif;
  --font-body: 'Be Vietnam Pro', sans-serif;

  /* Font Sizes */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-4xl: 2.5rem;
  --text-5xl: 3.5rem;
  --text-6xl: 4.5rem;

  /* Container */
  --container-max: 1200px;
  --container-padding: 1.5rem;
}

/* ==========================================================================
   Base Styles
   ========================================================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background: var(--gradient-bg);
  background-attachment: fixed;
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

/* Animated Background Lines */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background:
    linear-gradient(90deg, transparent 0%, transparent 49%, rgba(157, 0, 255, 0.03) 50%, transparent 51%, transparent 100%),
    linear-gradient(0deg, transparent 0%, transparent 49%, rgba(0, 217, 255, 0.03) 50%, transparent 51%, transparent 100%);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: -1;
}

/* ==========================================================================
   Typography
   ========================================================================== */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--space-md);
}

h1 {
  font-size: var(--text-5xl);
}

h2 {
  font-size: var(--text-4xl);
}

h3 {
  font-size: var(--text-3xl);
}

h4 {
  font-size: var(--text-2xl);
}

h5 {
  font-size: var(--text-xl);
}

h6 {
  font-size: var(--text-lg);
}

p {
  margin-bottom: var(--space-sm);
  color: var(--text-secondary);
}

a {
  color: var(--neon-blue);
  text-decoration: none;
  transition: var(--transition-normal);
}

a:hover {
  color: var(--neon-pink);
  text-shadow: var(--glow-pink);
}

/* ==========================================================================
   Utility Classes
   ========================================================================== */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--space-3xl) 0;
  position: relative;
}

.section-title {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.section-title h2 {
  display: inline-block;
  position: relative;
}

.section-title h2::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 100px;
  height: 3px;
  background: var(--gradient-neon-line);
  border-radius: 2px;
}

/* Gradient Text */
.gradient-text {
  background: var(--gradient-title);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Neon Glow Text */
.neon-text {
  text-shadow:
    0 0 5px var(--neon-pink),
    0 0 10px var(--neon-pink),
    0 0 20px var(--neon-pink);
}

.neon-text-blue {
  text-shadow:
    0 0 5px var(--neon-blue),
    0 0 10px var(--neon-blue),
    0 0 20px var(--neon-blue);
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-lg);
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  cursor: pointer;
  transition: var(--transition-normal);
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-button);
  color: var(--text-primary);
  box-shadow: var(--glow-pink);
}

.btn-primary:hover {
  background: var(--gradient-button-hover);
  transform: translateY(-3px);
  box-shadow: 0 0 30px rgba(255, 0, 127, 0.8), 0 0 60px rgba(255, 0, 127, 0.4);
  color: var(--text-primary);
}

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

.btn-outline:hover {
  background: var(--neon-blue);
  color: var(--text-dark);
  box-shadow: var(--glow-blue);
}

.btn-lg {
  padding: var(--space-md) var(--space-xl);
  font-size: var(--text-base);
}

/* ==========================================================================
   Cards
   ========================================================================== */
.card {
  background: var(--bg-card);
  border: 1px solid rgba(157, 0, 255, 0.3);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  backdrop-filter: blur(10px);
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-neon-line);
  opacity: 0;
  transition: var(--transition-normal);
}

.card:hover {
  background: var(--bg-card-hover);
  border-color: var(--neon-purple);
  transform: translateY(-5px);
  box-shadow: var(--glow-purple);
}

.card:hover::before {
  opacity: 1;
}

.card-icon {
  width: 70px;
  height: 70px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-card);
  border: 2px solid var(--neon-purple);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-md);
  font-size: var(--text-3xl);
}

.card-title {
  font-size: var(--text-xl);
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.card-text {
  color: var(--text-muted);
  font-size: var(--text-sm);
  line-height: 1.7;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-2xl) 0;
  position: relative;
  overflow: hidden;
}

/* Animated Neon Lines */
.hero::before,
.hero::after {
  content: '';
  position: absolute;
  height: 2px;
  background: var(--gradient-neon-line);
  animation: moveLine 4s linear infinite;
}

.hero::before {
  top: 20%;
  left: -100%;
  width: 200%;
}

.hero::after {
  bottom: 30%;
  right: -100%;
  width: 200%;
  animation-delay: 2s;
  animation-direction: reverse;
}

@keyframes moveLine {
  0% {
    transform: translateX(0);
  }

  100% {
    transform: translateX(50%);
  }
}

.hero-content {
  position: relative;
  z-index: 10;
  max-width: 900px;
  padding: 0 var(--container-padding);
}

.hero-logo {
  width: 180px;
  height: 180px;
  margin: 0 auto var(--space-lg);
  border-radius: var(--radius-full);
  overflow: hidden;
  border: 4px solid var(--neon-blue);
  box-shadow: var(--glow-blue);
  animation: float 3s ease-in-out infinite;
}

.hero-logo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

@keyframes float {

  0%,
  100% {
    transform: translateY(0);
  }

  50% {
    transform: translateY(-15px);
  }
}

.hero-subtitle {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--neon-blue);
  margin-bottom: var(--space-sm);
  letter-spacing: 3px;
  text-transform: uppercase;
}

.hero-title {
  font-size: var(--text-4xl);
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.hero-title-main {
  font-size: var(--text-5xl);
  font-weight: 900;
  margin-bottom: var(--space-md);
  line-height: 1.1;
}

.hero-tagline {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-xl);
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.hero-buttons {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* ==========================================================================
   Introduction Section
   ========================================================================== */
.intro {
  background: linear-gradient(180deg, transparent 0%, rgba(26, 10, 46, 0.5) 50%, transparent 100%);
}

.intro-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.intro-content p {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: var(--space-md);
}

.intro-highlight {
  display: inline-block;
  padding: var(--space-xs) var(--space-sm);
  background: var(--gradient-card);
  border: 1px solid var(--neon-purple);
  border-radius: var(--radius-sm);
  color: var(--neon-pink);
  font-weight: 600;
}

/* ==========================================================================
   Topics Section
   ========================================================================== */
.topics-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
}

.topic-card {
  position: relative;
}

.topic-card .card-icon {
  transition: var(--transition-normal);
}

.topic-card:hover .card-icon {
  border-color: var(--neon-pink);
  box-shadow: var(--glow-pink);
}

.topic-number {
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
  width: 35px;
  height: 35px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-button);
  border-radius: var(--radius-full);
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 700;
}

.topic-requirements {
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid rgba(157, 0, 255, 0.2);
}

.topic-requirements h4 {
  font-size: var(--text-sm);
  color: var(--neon-blue);
  margin-bottom: var(--space-xs);
  font-family: var(--font-display);
}

.topic-requirements ul {
  list-style: none;
  padding: 0;
}

.topic-requirements li {
  position: relative;
  padding-left: var(--space-md);
  margin-bottom: var(--space-xs);
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.topic-requirements li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--neon-pink);
}

.topic-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  margin-top: var(--space-sm);
  color: var(--neon-blue);
  font-size: var(--text-sm);
}

.topic-link:hover {
  color: var(--neon-pink);
}

/* ==========================================================================
   Prizes Section
   ========================================================================== */
.prizes {
  background: linear-gradient(180deg, transparent 0%, rgba(10, 26, 46, 0.5) 50%, transparent 100%);
}

.prizes-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-xl);
}

.prize-card {
  text-align: center;
  padding: var(--space-xl) var(--space-lg);
}

.prize-card.main {
  border-color: var(--gold);
}

.prize-card.main:hover {
  box-shadow: var(--glow-gold);
}

.prize-icon {
  font-size: var(--text-5xl);
  margin-bottom: var(--space-md);
}

.prize-rank {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--gold);
  margin-bottom: var(--space-sm);
  text-transform: uppercase;
  letter-spacing: 2px;
}

.prize-name {
  font-size: var(--text-xl);
  margin-bottom: var(--space-xs);
}

.prize-desc {
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.prizes-bonus {
  text-align: center;
  padding: var(--space-lg);
  background: var(--gradient-card);
  border: 1px dashed var(--neon-purple);
  border-radius: var(--radius-lg);
}

.prizes-bonus h4 {
  color: var(--neon-blue);
  margin-bottom: var(--space-sm);
}

/* ==========================================================================
   How to Join Section
   ========================================================================== */
.steps-container {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  position: relative;
}

.step {
  display: flex;
  gap: var(--space-lg);
  align-items: flex-start;
}

.step-number {
  flex-shrink: 0;
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-button);
  border-radius: var(--radius-full);
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  box-shadow: var(--glow-pink);
  position: relative;
}

.step-number::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 40px;
  background: linear-gradient(180deg, var(--neon-purple), transparent);
}

.step:last-child .step-number::after {
  display: none;
}

.step-content {
  flex: 1;
  padding-top: var(--space-sm);
}

.step-title {
  font-size: var(--text-lg);
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
}

.step-desc {
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.step-link {
  display: inline-block;
  margin-top: var(--space-xs);
  color: var(--neon-blue);
  font-size: var(--text-sm);
}

.hashtags {
  display: flex;
  gap: var(--space-xs);
  flex-wrap: wrap;
  margin-top: var(--space-xs);
}

.hashtag {
  display: inline-block;
  padding: 4px 12px;
  background: rgba(0, 217, 255, 0.1);
  border: 1px solid var(--neon-blue);
  border-radius: var(--radius-sm);
  color: var(--neon-blue);
  font-size: var(--text-xs);
  font-family: var(--font-display);
}

/* ==========================================================================
   Prize Claim Section
   ========================================================================== */
.claim-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

.claim-item {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-md);
  background: var(--bg-card);
  border: 1px solid rgba(157, 0, 255, 0.2);
  border-radius: var(--radius-md);
  transition: var(--transition-normal);
}

.claim-item:hover {
  border-color: var(--neon-purple);
  background: var(--bg-card-hover);
}

.claim-icon {
  flex-shrink: 0;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-card);
  border-radius: var(--radius-sm);
  font-size: var(--text-xl);
}

.claim-content h4 {
  font-size: var(--text-base);
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-weight: 600;
}

.claim-content p {
  color: var(--text-muted);
  font-size: var(--text-sm);
  margin: 0;
}

/* ==========================================================================
   Timeline Section
   ========================================================================== */
.timeline {
  background: linear-gradient(180deg, transparent 0%, rgba(26, 10, 46, 0.5) 50%, transparent 100%);
}

.timeline-container {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  margin-bottom: var(--space-2xl);
}

.timeline-item {
  text-align: center;
  padding: var(--space-xl);
  background: var(--bg-card);
  border: 2px solid var(--neon-purple);
  border-radius: var(--radius-lg);
  position: relative;
}

.timeline-item.active {
  border-color: var(--neon-pink);
  box-shadow: var(--glow-pink);
}

.timeline-label {
  position: absolute;
  top: -15px;
  left: 50%;
  transform: translateX(-50%);
  padding: var(--space-xs) var(--space-md);
  background: var(--gradient-button);
  border-radius: var(--radius-sm);
  font-family: var(--font-display);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.timeline-icon {
  font-size: var(--text-4xl);
  margin-bottom: var(--space-md);
}

.timeline-title {
  font-size: var(--text-lg);
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.timeline-date {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  color: var(--neon-blue);
  text-shadow: var(--glow-blue);
}

/* Countdown */
.countdown-container {
  text-align: center;
}

.countdown-title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
  text-transform: uppercase;
  letter-spacing: 3px;
}

.countdown {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.countdown-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 80px;
}

.countdown-value {
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  font-weight: 700;
  color: var(--text-primary);
  background: var(--bg-card);
  border: 2px solid var(--neon-pink);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  box-shadow: var(--glow-pink);
  min-width: 90px;
  text-align: center;
}

.countdown-label {
  margin-top: var(--space-xs);
  font-size: var(--text-sm);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.countdown-separator {
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  color: var(--neon-purple);
  align-self: flex-start;
  padding-top: var(--space-md);
  animation: blink 1s ease-in-out infinite;
}

@keyframes blink {

  0%,
  100% {
    opacity: 1;
  }

  50% {
    opacity: 0.3;
  }
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
  padding: var(--space-2xl) 0;
  border-top: 1px solid rgba(157, 0, 255, 0.2);
  text-align: center;
}

.footer-logo {
  width: 80px;
  height: 80px;
  margin: 0 auto var(--space-md);
  border-radius: var(--radius-full);
  overflow: hidden;
  border: 2px solid var(--neon-blue);
}

.footer-logo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.footer-brand {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  margin-bottom: var(--space-lg);
  color: var(--text-primary);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
  margin-bottom: var(--space-xl);
}

.footer-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  background: var(--bg-card);
  border: 1px solid rgba(157, 0, 255, 0.3);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: var(--transition-normal);
}

.footer-link:hover {
  border-color: var(--neon-blue);
  color: var(--neon-blue);
  box-shadow: var(--glow-blue);
}

.footer-link svg {
  width: 20px;
  height: 20px;
}

.footer-quote {
  max-width: 600px;
  margin: 0 auto var(--space-lg);
  padding: var(--space-md);
  background: var(--gradient-card);
  border-left: 3px solid var(--neon-pink);
  border-radius: var(--radius-sm);
  font-style: italic;
  color: var(--text-secondary);
}

.footer-copyright {
  color: var(--text-muted);
  font-size: var(--text-sm);
}

/* ==========================================================================
   Sponsor / Partnership Section
   ========================================================================== */
.sponsor-content {
  max-width: 800px;
  margin: 0 auto;
}

.sponsor-card {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-md);
  background: var(--bg-card);
  border: 1px solid rgba(255, 165, 0, 0.3);
  border-radius: var(--radius-lg);
  transition: var(--transition-normal);
}

.sponsor-card:hover {
  border-color: var(--gold);
  box-shadow: var(--glow-gold);
  transform: translateY(-3px);
}

.sponsor-icon {
  flex-shrink: 0;
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(145deg, rgba(255, 165, 0, 0.2), rgba(255, 204, 0, 0.1));
  border: 2px solid var(--gold);
  border-radius: var(--radius-md);
  font-size: var(--text-3xl);
}

.sponsor-text {
  flex: 1;
}

.sponsor-text p {
  color: var(--text-secondary);
  font-size: var(--text-lg);
  line-height: 1.8;
  margin: 0;
}

.sponsor-text strong {
  color: var(--text-primary);
}

.highlight-text {
  color: var(--gold);
  font-weight: 600;
}

.sponsor-cta {
  text-align: center;
  margin-top: var(--space-xl);
  padding: var(--space-lg);
  background: var(--gradient-card);
  border: 1px dashed var(--gold);
  border-radius: var(--radius-lg);
}

.sponsor-cta p {
  font-size: var(--text-lg);
  margin-bottom: var(--space-md);
  color: var(--text-secondary);
}

.sponsor-links {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
}

.sponsor-links .btn-outline {
  border-color: var(--gold);
  color: var(--gold);
}

.sponsor-links .btn-outline:hover {
  background: var(--gold);
  color: var(--text-dark);
  box-shadow: var(--glow-gold);
}

/* Sponsors Section - Nhà Tài Trợ */
.sponsors-section {
  margin-top: var(--space-2xl);
  padding: var(--space-xl);
  background: linear-gradient(145deg, rgba(157, 0, 255, 0.08), rgba(0, 217, 255, 0.05));
  border: 1px solid rgba(255, 165, 0, 0.2);
  border-radius: var(--radius-xl);
  position: relative;
  overflow: hidden;
}

.sponsors-section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--gold), var(--neon-pink), var(--gold), transparent);
}

.sponsors-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.sponsors-icon {
  font-size: var(--text-5xl);
  margin-bottom: var(--space-sm);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.1);
  }
}

.sponsors-title {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  background: linear-gradient(90deg, var(--gold), var(--gold-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-xs);
}

.sponsors-subtitle {
  color: var(--text-muted);
  font-size: var(--text-base);
  margin: 0;
}

.sponsors-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.sponsor-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: var(--space-md);
  background: var(--bg-card);
  border: 1px solid rgba(157, 0, 255, 0.3);
  border-radius: var(--radius-lg);
  transition: var(--transition-normal);
  position: relative;
  text-decoration: none;
  color: inherit;
  cursor: default;
}

.sponsor-item:hover {
  background: var(--bg-card-hover);
  border-color: var(--neon-purple);
  transform: translateY(-5px);
  box-shadow: var(--glow-purple);
}

/* Featured Sponsor */
.sponsor-item.featured {
  border-color: var(--gold);
  background: linear-gradient(145deg, rgba(255, 165, 0, 0.1), rgba(255, 204, 0, 0.05));
  cursor: pointer;
}

.sponsor-item.featured:hover {
  border-color: var(--gold-light);
  box-shadow: var(--glow-gold);
  color: inherit;
}

.sponsor-item.featured .sponsor-avatar {
  border-color: var(--gold);
  background: linear-gradient(145deg, rgba(255, 165, 0, 0.2), rgba(255, 204, 0, 0.1));
}

/* Anonymous Sponsor */
.sponsor-item.anonymous {
  border-style: dashed;
  border-color: rgba(255, 255, 255, 0.2);
}

.sponsor-item.anonymous:hover {
  border-color: var(--neon-blue);
  box-shadow: var(--glow-blue);
}

.sponsor-badge {
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%);
  padding: 2px 10px;
  background: var(--gradient-button);
  border-radius: var(--radius-sm);
  font-family: var(--font-display);
  font-size: var(--text-xs);
  white-space: nowrap;
}

.sponsor-item.featured .sponsor-badge {
  background: linear-gradient(90deg, var(--gold-dark), var(--gold));
}

.sponsor-item.anonymous .sponsor-badge {
  background: linear-gradient(90deg, var(--neon-blue-dark), var(--neon-blue));
}

.sponsor-avatar {
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-card);
  border: 2px solid var(--neon-purple);
  border-radius: var(--radius-full);
  font-size: var(--text-2xl);
  margin: var(--space-sm) 0;
}

.sponsor-name {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-primary);
  text-align: center;
  line-height: 1.4;
}

.sponsor-item.anonymous .sponsor-name {
  color: var(--text-muted);
  font-style: italic;
}

.sponsors-thanks {
  text-align: center;
  padding: var(--space-md);
  background: var(--gradient-card);
  border-left: 3px solid var(--gold);
  border-radius: var(--radius-sm);
}

.sponsors-thanks p {
  color: var(--text-secondary);
  font-size: var(--text-base);
  margin: 0;
}

/* ==========================================================================
   Animations
   ========================================================================== */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-on-scroll.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger animation for grid items */
.animate-stagger>*:nth-child(1) {
  transition-delay: 0.1s;
}

.animate-stagger>*:nth-child(2) {
  transition-delay: 0.2s;
}

.animate-stagger>*:nth-child(3) {
  transition-delay: 0.3s;
}

.animate-stagger>*:nth-child(4) {
  transition-delay: 0.4s;
}

.animate-stagger>*:nth-child(5) {
  transition-delay: 0.5s;
}

/* Pulse animation */
@keyframes pulse {

  0%,
  100% {
    transform: scale(1);
  }

  50% {
    transform: scale(1.05);
  }
}

.pulse {
  animation: pulse 2s ease-in-out infinite;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */

/* Small devices (landscape phones, 576px and up) */
@media (min-width: 576px) {
  .countdown-value {
    font-size: var(--text-5xl);
    min-width: 100px;
  }

  .countdown-separator {
    font-size: var(--text-5xl);
  }
}

/* Medium devices (tablets, 768px and up) */
@media (min-width: 768px) {
  :root {
    --text-5xl: 4rem;
    --text-6xl: 5rem;
  }

  .topics-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .prizes-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .claim-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .timeline-container {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-logo {
    width: 200px;
    height: 200px;
  }
}

/* Large devices (desktops, 992px and up) */
@media (min-width: 992px) {
  :root {
    --text-5xl: 4.5rem;
    --text-6xl: 6rem;
  }

  .topics-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .prizes-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .hero-logo {
    width: 220px;
    height: 220px;
  }

  .hero-title-main {
    font-size: var(--text-6xl);
  }
}

/* Extra large devices (large desktops, 1200px and up) */
@media (min-width: 1200px) {
  .container {
    max-width: 1140px;
  }
}

/* Mobile specific adjustments */
@media (max-width: 575.98px) {
  .hero-title-main {
    font-size: var(--text-3xl);
  }

  .hero-subtitle {
    font-size: var(--text-base);
  }

  .btn-lg {
    padding: var(--space-sm) var(--space-lg);
    font-size: var(--text-sm);
  }

  .countdown-value {
    font-size: var(--text-2xl);
    min-width: 60px;
    padding: var(--space-sm) var(--space-md);
  }

  .countdown-separator {
    font-size: var(--text-2xl);
    padding-top: var(--space-sm);
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .footer-links {
    flex-direction: column;
    align-items: center;
  }
}