body {
  scroll-behavior: smooth;
  font-family: "Segoe UI", sans-serif;
}

.hero {
  background: linear-gradient(135deg, #007bff, #6610f2);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.service-card:hover {
  transform: translateY(-5px);
  transition: all 0.3s;
}

.portfolio-item img {
  transition: transform 0.3s;
}

.portfolio-item img:hover {
  transform: scale(1.05);
}

.btn-primary {
  background: linear-gradient(90deg, #007bff, #00c4ff);
  border: none;
}

/* Navbar Tech Style */
.tech-navbar {
  background: linear-gradient(90deg, rgba(10,25,47,0.95) 0%, rgba(22,9,63,0.95) 50%, rgba(5,17,36,0.95) 100%);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(0, 255, 255, 0.2);
  transition: all 0.4s ease;
}

.tech-navbar .navbar-brand {
  font-size: 1.4rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.text-glow {
  color: #00eaff;
  text-shadow: 0 0 8px #00eaff, 0 0 16px #00bfff;
}

.tech-navbar .nav-link {
  color: #dfe6f0 !important;
  font-weight: 500;
  text-transform: uppercase;
  position: relative;
  margin-left: 18px;
  letter-spacing: 0.5px;
  transition: color 0.3s ease;
}

.tech-navbar .nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0%;
  height: 2px;
  background: linear-gradient(90deg, #00eaff, #6f00ff);
  transition: all 0.3s ease;
  transform: translateX(-50%);
}

.tech-navbar .nav-link:hover::after {
  width: 60%;
}

.tech-navbar .nav-link:hover {
  color: #00eaff !important;
  text-shadow: 0 0 5px #00eaff;
}

/* Hiệu ứng đổi nền khi cuộn */
.tech-navbar.scrolled {
  background: linear-gradient(90deg, rgba(5, 10, 25, 0.95), rgba(9, 20, 50, 0.95));
  box-shadow: 0 2px 10px rgba(0,255,255,0.15);
}

.hero {
  position: relative;
  height: 100vh;
  color: white;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
}

.hero video {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  object-fit: cover;
  z-index: -2;
  filter: brightness(0.4);
}

#particles-js {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  z-index: -1;
  pointer-events: none;
}

.hero .overlay-content {
  position: relative;
  z-index: 1;
}

/* =============================
   🌌 STYLE CHO TRANG CHỦ
   ============================= */

/* Reset & Font */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background: linear-gradient(180deg, #070a1a, #0b1030 80%);
  color: #fff;
  font-family: 'Roboto', sans-serif;
  overflow-x: hidden;
  scroll-behavior: smooth;
}

/* Navbar */
.navbar {
  background: rgba(10, 14, 35, 0.85);
  backdrop-filter: blur(8px);
  transition: all 0.3s ease;
}

.navbar.scrolled {
  background: rgba(0, 0, 0, 0.9);
  box-shadow: 0 0 10px rgba(0,255,255,0.2);
}

.navbar-brand {
  font-family: 'Orbitron', sans-serif;
  color: #00ffe7 !important;
}

/* HERO SECTION */
#hero {
  position: relative;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  overflow: hidden;
}

#hero video {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  object-fit: cover;
  z-index: -2;
}

.hero-overlay {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.6);
  z-index: -1;
}

.hero-content {
  z-index: 2;
  color: #fff;
  text-shadow: 0 0 20px rgba(0,255,255,0.5);
  animation: fadeUp 1.5s ease;
}

.hero-content h1 {
  font-family: 'Orbitron', sans-serif;
  font-size: 2.8rem;
  color: #00ffe7;
}

/* Sections chung */
section {
  position: relative;
  overflow: hidden;
}

/* Hiệu ứng hạt sáng */
.particles-container {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  z-index: 0;
}

/* Contact + Portfolio có hạt riêng */
#portfolio .particles-container,
#contact .particles-container {
  opacity: 0.5;
  pointer-events: none;
}

/* Fade-in & slide hiệu ứng */
.fade-in {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 1s ease, transform 1s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.slide-right {
  opacity: 0;
  transform: translateX(60px);
  transition: all 1s ease;
}

.slide-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* Nút scroll lên top */
#scrollTopBtn {
  position: fixed;
  bottom: 25px;
  right: 25px;
  z-index: 1000;
  background: linear-gradient(90deg,#00ffe7,#007bff);
  color: #fff;
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  font-size: 20px;
  cursor: pointer;
  box-shadow: 0 0 15px rgba(0,255,255,0.4);
  transition: all 0.3s ease;
}
#scrollTopBtn:hover {
  transform: scale(1.1);
}

/* Nút Zalo */
#zaloBtn {
  position: fixed;
  bottom: 25px;
  right: 85px;
  z-index: 1000;
  background: #0084ff;
  color: #fff;
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 22px;
  box-shadow: 0 0 12px rgba(0,132,255,0.6);
  transition: all 0.3s ease;
}
#zaloBtn:hover {
  transform: scale(1.1);
  background: #00aaff;
}

/* Portfolio */
.portfolio-item {
  background: rgba(255,255,255,0.05);
  border-radius: 12px;
  transition: transform 0.4s ease, box-shadow 0.4s ease;
}
.portfolio-item:hover {
  transform: translateY(-5px) scale(1.02);
  box-shadow: 0 0 20px rgba(0,255,255,0.2);
}

/* Contact */
.contact-input {
  background: rgba(255,255,255,0.05);
  border: 1px solid #00ffe7;
  color: #fff;
}
.contact-input:focus {
  border-color: #00ffe7;
  box-shadow: 0 0 10px rgba(0,255,255,0.4);
  background: rgba(255,255,255,0.08);
}

/* Footer */
footer {
  background: linear-gradient(90deg, #007bff, #00ffe7);
  color: #0a0e23;
  text-align: center;
  padding: 14px;
  font-weight: 500;
}

/* Animation keyframes */
@keyframes fadeUp {
  from {opacity: 0; transform: translateY(40px);}
  to {opacity: 1; transform: translateY(0);}
}