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

:root {
  --primary-color: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #3b82f6;
  --secondary-color: #64748b;
  --accent-color: #f59e0b;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-light: #94a3b8;
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-accent: #f1f5f9;
  --border-color: #e2e8f0;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --gradient: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  --max-width: 1200px;
  --border-radius: 8px;
  --border-radius-lg: 12px;
  --transition: all 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  overflow-x: hidden;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition);
}

.navbar.scrolled {
  background: rgba(255, 255, 255, 0.98);
  box-shadow: var(--shadow-md);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  text-decoration: none;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2rem;
  align-items: center;
}

.nav-link {
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
  position: relative;
  transition: var(--transition);
}

.nav-link:hover {
  color: var(--primary-color);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient);
  transition: var(--transition);
}

.nav-link:hover::after {
  width: 100%;
}

.hamburger {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 4px;
}

.hamburger span {
  width: 25px;
  height: 3px;
  background: var(--text-primary);
  transition: var(--transition);
}

.hamburger.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -6px);
}

/* Hero section */
.hero {
  padding: 120px 0 80px;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(37, 99, 235, 0.1) 0%, transparent 70%);
  pointer-events: none;
}

.hero-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.highlight {
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: var(--primary-color);
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero-description {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  line-height: 1.7;
}

.hero-buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  padding: 12px 24px;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  cursor: pointer;
  border: none;
  font-size: 1rem;
}

.btn-primary {
  background: var(--gradient);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

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

.btn-secondary:hover {
  background: var(--primary-color);
  color: white;
  transform: translateY(-2px);
}

.hero-image {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

.profile-image {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  object-fit: cover;
  border: 5px solid white;
  box-shadow: var(--shadow-xl);
  position: relative;
  z-index: 2;
}

.image-backdrop {
  position: absolute;
  width: 320px;
  height: 320px;
  background: var(--gradient);
  border-radius: 50%;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 1;
  opacity: 0.1;
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translate(-50%, -50%) translateY(0px); }
  50% { transform: translate(-50%, -50%) translateY(-20px); }
}

/* Section styles */
section {
  padding: 80px 0;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--text-primary);
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--gradient);
  border-radius: 2px;
}

/* About section */
.about {
  background: var(--bg-secondary);
}

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

.about-text p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  line-height: 1.8;
}

.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.stat-item {
  text-align: center;
  padding: 1.5rem;
  background: white;
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.stat-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.stat-number {
  display: block;
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--text-secondary);
  font-weight: 500;
}

/* Skills section */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.skill-category {
  background: white;
  padding: 2rem;
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.skill-category:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.skill-category h3 {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  text-align: center;
}

.skill-items {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.skill-tag {
  display: inline-block;
  padding: 8px 16px;
  background: var(--bg-accent);
  color: var(--text-primary);
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: var(--transition);
  border: 1px solid var(--border-color);
}

.skill-tag:hover {
  background: var(--primary-color);
  color: white;
  transform: translateY(-2px);
}

/* Projects section */
.projects {
  background: var(--bg-secondary);
}

.enterprise-projects {
  background: var(--bg-primary);
  padding: 80px 0;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
}

.project-card {
  background: white;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
}

.project-card.featured {
  border: 2px solid var(--primary-color);
  position: relative;
}

.project-card.featured::before {
  content: '⭐ Featured';
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: var(--gradient);
  color: white;
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 500;
  z-index: 10;
}

.project-image {
  position: relative;
  height: 200px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.project-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: var(--transition);
}

.project-card:hover .project-overlay {
  opacity: 1;
}

.project-links {
  display: flex;
  gap: 1rem;
}

.project-link {
  background: white;
  color: var(--text-primary);
  padding: 8px 16px;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.project-link:hover {
  background: var(--primary-color);
  color: white;
  transform: scale(1.05);
}

.project-content {
  padding: 2rem;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.project-content h3 {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.project-content p {
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 1.5rem;
  flex: 1;
}

.project-tech {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tech-tag {
  background: var(--bg-accent);
  color: var(--text-primary);
  padding: 4px 12px;
  border-radius: 16px;
  font-size: 0.8rem;
  font-weight: 500;
  border: 1px solid var(--border-color);
}

/* Enterprise project styles */
.project-card.enterprise {
  border: 2px solid var(--accent-color);
  position: relative;
}

.project-card.enterprise::before {
  content: '💼 Enterprise';
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: linear-gradient(135deg, var(--accent-color), #d97706);
  color: white;
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 500;
  z-index: 10;
}

.project-placeholder {
  /* block-level để chứa cả đoạn văn + ul */
  display: block;
  background: linear-gradient(
    to right,
    rgba(32, 34, 37, 0.9),
    rgba(40, 42, 48, 0.9)
  );
  border-radius: 12px;
  padding: 1.8rem;
  color: var(--text-light);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
  margin-bottom: 2rem;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

/* Căn chỉnh câu mở đầu */
.project-placeholder > p {
  margin: 0 0 1rem;
  font-weight: 500;
  line-height: 1.4;
}

/* Style list */
.project-placeholder ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.project-placeholder ul li {
  position: relative;
  padding-left: 1.6rem;
  margin-bottom: 0.75rem;
  line-height: 1.5;
}
.project-placeholder ul li::before {
  content: "✔";
  position: absolute;
  left: 0;
  top: 0;
  font-size: 0.9rem;
  color: var(--primary-color);
}

/* Hover nâng nhẹ block */
.project-placeholder:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.5);
}



/* Contact section */
.contact-description {
  text-align: center;
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.contact-methods {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  max-width: 800px;
  margin: 0 auto;
}

.contact-item {
  display: flex;
  align-items: center;
  padding: 2rem;
  background: white;
  border-radius: var(--border-radius-lg);
  text-decoration: none;
  color: inherit;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.contact-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-color);
}

.contact-icon {
  font-size: 2rem;
  margin-right: 1.5rem;
  flex-shrink: 0;
}

.contact-details {
  display: flex;
  flex-direction: column;
}

.contact-label {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.contact-value {
  color: var(--text-secondary);
}

/* Footer */
.footer {
  background: var(--text-primary);
  color: white;
  padding: 2rem 0;
  text-align: center;
}

.footer-content p {
  margin-bottom: 0.5rem;
}

.footer-note {
  color: var(--text-light);
  font-size: 0.9rem;
}

/* Responsive design */
@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background-color: white;
    width: 100%;
    text-align: center;
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
    padding: 2rem 0;
  }

  .nav-menu.active {
    left: 0;
  }

  .hamburger {
    display: flex;
  }

  .hero {
    padding: 100px 0 60px;
  }

  .hero-content {
    grid-template-columns: 1fr;
    gap: 3rem;
    text-align: center;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1.3rem;
  }

  .profile-image {
    width: 250px;
    height: 250px;
  }

  .image-backdrop {
    width: 270px;
    height: 270px;
  }

  .section-title {
    font-size: 2rem;
  }

  .stats {
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .hero-buttons {
    justify-content: center;
  }

  section {
    padding: 60px 0;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 0.75rem;
  }

  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1.1rem;
  }

  .hero-description {
    font-size: 1rem;
  }

  .btn {
    padding: 10px 20px;
    font-size: 0.9rem;
  }

  .profile-image {
    width: 200px;
    height: 200px;
  }

  .image-backdrop {
    width: 220px;
    height: 220px;
  }

  .skill-category,
  .project-card,
  .contact-item {
    padding: 1.5rem;
  }

  .contact-methods {
    grid-template-columns: 1fr;
  }
}

/* Dark mode support (optional) */
@media (prefers-color-scheme: dark) {
  :root {
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-light: #94a3b8;
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-accent: #334155;
    --border-color: #334155;
  }

  .navbar {
    background: rgba(15, 23, 42, 0.95);
  }

  .navbar.scrolled {
    background: rgba(15, 23, 42, 0.98);
  }

  .skill-category,
  .project-card,
  .contact-item,
  .stat-item {
    background: var(--bg-secondary);
    border-color: var(--border-color);
  }

  .skill-tag,
  .tech-tag {
    background: var(--bg-accent);
    border-color: var(--border-color);
  }
}

/* Animation for smooth loading */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero-content,
.section-title,
.project-card,
.skill-category,
.contact-item {
  animation: fadeInUp 0.8s ease-out;
}

/* Scrollbar styling */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--primary-color);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--primary-dark);
}