* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}
html, body {
  width: 100%;
  height: 100%;
  overflow-x: hidden;
  position: relative;
  background: #000;
  z-index: 1;
}

/* 🔥 Background video styling */
.bg-video {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  object-fit: cover;
  z-index: -10;
  filter: brightness(0.5) blur(5px);
}

/* Overlay for darkening (if needed) */
body::before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0);
  z-index: -9;
}

/* ------------------ NAVIGATION BAR ----------------------------------------------------------- */
.header {
  width: 100%;
  padding: 20px 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: fixed;
  top: 0;
  left: 0;
  background: rgba(0,0,0,0.3);
  backdrop-filter: blur(8px);
  z-index: 100;
  box-shadow: 0 0 10px rgba(0,0,0,0.4);
}

.logo {
  font-size: 24px;
  font-weight: 600;
  color: #ffffff;
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.logo i {
  font-size: 28px;
  color: white;
}

.nav-links {
  display: flex;
  align-items: center;
}

.nav-links a {
  color: #ffffff;
  text-decoration: none;
  margin-left: 30px;
  font-size: 18px;
  font-weight: 500;
  position: relative;
  transition: color 0.3s, transform 0.3s;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.nav-links a i {
  font-size: 20px;
}

.nav-links a::after {
  content: "";
  position: absolute;
  width: 100%;
  height: 2px;
  left: 0;
  bottom: -6px;
  background: #00e6e6;
  border-radius: 5px;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.4s ease;
}

.nav-links a:hover {
  color: #00e6e6;
  transform: scale(1.05);
}

.nav-links a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

.nav-links a:hover {
  color: #00e6e6;
  transform: scale(1.1);
}

.nav-links a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* Challenge Section */
.challenge-section {
  padding: 60px 20px;
  background: linear-gradient(to bottom right, #042828, #0e1e1e);
}

.container {
  padding-top: 100px;
  max-width: 1100px;
  margin: auto;
  text-align: center;
}

.challenge-section h1 {
  font-size: 42px;
  color: #00e6e6;
  margin-bottom: 10px;
}
.challenge-section {
  background: rgba(0, 0, 0, 0.4); /* semi-transparent background */
  padding: 30px;
}

/* Transparent text inside */
.challenge-section h2,
.challenge-section p {
  color: rgba(255, 255, 255, 0.75); /* light transparent white */
}

.challenge-section .intro {
  font-size: 18px;
  color: #ccc;
  margin-bottom: 40px;
}

.challenge-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 30px;
}

.challenge-card {
  background: transparent;
  padding: 30px;
  border-radius: 16px;
  width: 300px;
  text-align: center;
  box-shadow: 0 0 15px rgba(0, 230, 230, 0.5);
  transition: transform 0.3s, box-shadow 0.3s;
  backdrop-filter: blur(10px);
}

.challenge-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 0 25px rgba(0, 230, 230, 0.7);
}

.challenge-card i {
  font-size: 48px;
  color: #00e6e6;
  margin-bottom: 16px;
}

.challenge-card h3 {
  font-size: 22px;
  margin-bottom: 10px;
  color: #00e6e6;
}

.challenge-card p {
  font-size: 16px;
  color: #ccc;
  margin-bottom: 20px;
}

.btn-glow {
  display: inline-block;
  padding: 10px 24px;
  color: #00e6e6;
  font-size: 16px;
  font-weight: 600;
  text-decoration: none;
  border: 2px solid #00e6e6;
  border-radius: 8px;
  background: transparent;
  position: relative;
  overflow: hidden;
  transition: color 0.3s, box-shadow 0.3s;
  cursor: pointer;
}

.btn-glow::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: #00e6e6;
  opacity: 0;
  z-index: -1;
  border-radius: 50%;
  transition: opacity 0.3s;
}

.btn-glow:hover {
  color: white;
  box-shadow: 0 0 8px #00e6e6, 0 0 16px #00e6e6;
}

.btn-glow:hover::before {
  opacity: 0.15;
}