/* Reset and base */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: #121212;
  color: #e0e0e0;
  font-family: 'Roboto', sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Background & Overlay */
.background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: url('assets/images/background.jpeg') no-repeat center center / cover;
  z-index: 0;
  filter: brightness(0.1);
}

.circuit-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: repeating-linear-gradient(
    45deg,
    rgba(0, 255, 255, 0.07),
    rgba(0, 255, 255, 0.07) 2px,
    transparent 2px,
    transparent 6px
  );
  animation: pulse 3s infinite alternate;
  pointer-events: none;
  z-index: 1;
}

@keyframes pulse {
  0% {
    opacity: 0.2;
    filter: drop-shadow(0 0 6px cyan);
  }
  100% {
    opacity: 0.45;
    filter: drop-shadow(0 0 14px cyan);
  }
}

/* Header */
.header {
  position: relative;
  z-index: 10;
  background: rgba(0, 0, 0, 0.75);
  border-bottom: 2px solid #00ffff;
  border-radius: 0 0 15px 15px;
  box-shadow: 0 0 20px #00ffff;
  padding: 20px 30px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 15px;
}

.logo {
  height: 80px;
  border-radius: 12px;
  flex-shrink: 0;
}

.header-text {
  flex-grow: 1;
  min-width: 200px;
}

.header-text h1 {
  font-size: 2.6rem;
  font-weight: 700;
  color: #00ffff;
  text-shadow: 0 0 10px #00ffff;
}

.tagline {
  color: #32ff7e;
  font-weight: 500;
  font-size: 1.2rem;
  margin-top: 6px;
  text-shadow: 0 0 8px #32ff7e;
}

/* Navigation */
nav {
  width: 100%;
  margin-top: 10px;
  text-align: center;
}

.nav-tabs {
  list-style: none;
  display: inline-flex;
  gap: 22px;
  font-weight: 600;
  font-size: 1.1rem;
}

.nav-tabs li a {
  color: #00ffff;
  padding: 10px 26px;
  border: 2px solid #00ffff;
  border-radius: 10px;
  text-decoration: none;
  box-shadow: 0 0 10px #00ffff;
  transition: all 0.3s ease;
  cursor: pointer;
  display: inline-block;
}

.nav-tabs li a.active,
.nav-tabs li a:hover,
.nav-tabs li a:focus {
  background-color: #00ffff;
  color: #121212;
  box-shadow: 0 0 18px #ff3f3f;
  outline: none;
}

/* Main content container */
.tab-content-wrapper {
  position: relative;
  max-width: 960px;
  margin: 30px auto 60px auto;
  overflow: hidden;
  border-radius: 18px;
  box-shadow: 0 0 30px #00ffff;
  background-color: rgba(18, 18, 18, 0.95);
  border: 2px solid #00ffff;
  min-height: 300px;
  z-index: 10;
}

/* Flex container for tabs */
.tab-content {
  display: flex;
  transition: transform 0.4s ease;
  width: 400%; /* 4 tabs */
}

/* Each tab panel */
.tab-panel {
  flex: 0 0 25%;
  padding: 30px 40px;
  box-sizing: border-box;
  color: #c0ffff;
  outline: none;
}

.tab-panel h2 {
  color: #00ffff;
  border-bottom: 2px solid #ff3f3f;
  padding-bottom: 8px;
  margin-bottom: 20px;
  font-weight: 700;
  font-size: 2rem;
  text-shadow: 0 0 12px #00ffff;
}

.features-list {
  padding-left: 25px;
  font-weight: 500;
  font-size: 1.1rem;
  color: #a0f0f0;
  list-style-type: disc;
  line-height: 1.7;
}

.features-list li {
  margin-bottom: 14px;
}

/* Download button */
.download-button {
  background: linear-gradient(45deg, #00ffff, #0077ff);
  color: #121212;
  border: none;
  padding: 16px 42px;
  font-weight: 700;
  border-radius: 14px;
  box-shadow: 0 0 28px #00ffff;
  cursor: pointer;
  transition: all 0.3s ease-in-out;
  display: inline-block;
  margin-top: 18px;
  text-decoration: none;
  text-align: center;
}

.download-button:hover,
.download-button:focus {
  background: linear-gradient(45deg, #ff0000, #8b0000);
  color: #fff;
  box-shadow: 0 0 38px #ff0000;
  outline: none;
}

/* Note under download */
.note {
  margin-top: 14px;
  font-size: 0.95rem;
  color: #70d6f9;
  font-weight: 500;
  max-width: 320px;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

/* About Us extended text */
.tab-panel h3 {
  color: #ff3f3f;
  margin-top: 25px;
  margin-bottom: 10px;
  font-weight: 700;
  font-size: 1.4rem;
  text-shadow: 0 0 8px #ff3f3f;
}

/* Links */
a {
  color: #00ffff;
  font-weight: 600;
  text-decoration: none;
  transition: color 0.3s ease, text-shadow 0.3s ease;
  outline-offset: 2px;
}

a:hover,
a:focus {
  color: #32ff7e;
  text-shadow: 0 0 10px #32ff7e, 0 0 16px #32ff7e;
  outline: none;
}

/* Footer */
.footer {
  background-color: rgba(18, 18, 18, 0.85);
  border-top: 2px solid #ff3f3f;
  color: #888;
  box-shadow: 0 -2px 15px #ff3f3f;
  border-radius: 15px 15px 0 0;
  text-align: center;
  padding: 15px 10px;
  font-size: 0.9rem;
  position: relative;
  z-index: 10;
}

/* Social links */
.social-links {
  list-style: none;
  display: flex;
  gap: 20px;