/* ========================================
   PHẠM TẤN GIÀU - MODERN PORTFOLIO
   Pure CSS - Clean, Well-Commented, Responsive
   ======================================== */

/* CSS Custom Properties (Theme Variables) */
:root {
  /* Dark Theme (Default) */
  --bg-primary: #0f172a;
  --bg-secondary: #1e2937;
  --bg-card: #1e2937;
  --bg-glass: rgba(30, 41, 55, 0.85);
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-primary: #6366f1;
  --accent-secondary: #10b981;
  --accent-green: #22c55e;
  --border-color: #334155;
  --shadow-soft: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-strong: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --gradient-hero: linear-gradient(135deg, #0f172a 0%, #1e2937 100%);
  --gradient-accent: linear-gradient(90deg, #6366f1, #10b981);
}

/* Light Theme */
body.light-mode {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-glass: rgba(255, 255, 255, 0.9);
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --accent-primary: #6366f1;
  --accent-secondary: #059669;
  --accent-green: #16a34a;
  --border-color: #e2e8f0;
  --shadow-soft: 0 10px 15px -3px rgb(0 0 0 / 0.05), 0 4px 6px -4px rgb(0 0 0 / 0.05);
  --shadow-strong: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --gradient-hero: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 100%);
}

/* Base Reset & Typography */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: 'Inter', system_ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background-color 0.3s ease, color 0.3s ease;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 { font-size: clamp(2.5rem, 6vw, 4.5rem); }
h2 { font-size: clamp(2rem, 5vw, 3rem); }
h3 { font-size: clamp(1.25rem, 3vw, 1.75rem); }

p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--accent-primary);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Utility Classes */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 6rem 0;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -12px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--gradient-accent);
  border-radius: 2px;
}

.glass {
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-color);
}

/* ========================================
   NAVBAR
   ======================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 1rem 0;
  transition: all 0.3s ease;
}

.navbar.scrolled {
  background: var(--bg-glass);
  box-shadow: var(--shadow-soft);
  padding: 0.75rem 0;
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

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

.nav-links a {
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: 0.5rem 0;
}

.nav-links a:hover {
  color: var(--text-primary);
}

.nav-links a.active {
  color: var(--text-primary);
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--gradient-accent);
  border-radius: 2px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Theme & Music Toggle Buttons */
.toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 9999px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 1.1rem;
}

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

.music-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: 9999px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.music-btn:hover {
  background: var(--accent-secondary);
  color: white;
  border-color: var(--accent-secondary);
}

.music-btn.playing {
  background: var(--accent-secondary);
  color: white;
  border-color: var(--accent-secondary);
  animation: pulse 2s infinite ease-in-out;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.4); }
  50% { box-shadow: 0 0 0 8px rgba(16, 185, 129, 0); }
}

/* Hamburger Menu */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  z-index: 1001;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  transition: all 0.3s ease;
}

.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(5px, -5px); }

/* Mobile Menu */
.mobile-menu {
  display: none;
  position: fixed;
  top: 70px;
  left: 0;
  right: 0;
  background: var(--bg-primary);
  padding: 2rem;
  border-bottom: 1px solid var(--border-color);
  z-index: 999;
  flex-direction: column;
  gap: 1.5rem;
}

.mobile-menu.active {
  display: flex;
}

.mobile-menu a {
  font-size: 1.1rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border-color);
}

/* ========================================
   HERO SECTION
   ======================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 5rem;
  background: var(--gradient-hero);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  align-items: center;
}

@media (min-width: 1024px) {
  .hero-content {
    grid-template-columns: 1fr 420px;
    gap: 4rem;
  }
}

.hero-text h1 {
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.verified-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: linear-gradient(90deg, #166534, #15803d);
  color: white;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.35rem 0.9rem;
  border-radius: 9999px;
  box-shadow: 0 0 0 4px rgba(34, 197, 94, 0.2);
  animation: badge-pop 0.6s cubic-bezier(0.34, 1.56, 0.64, 1), badge-glow 2s ease-in-out infinite;
  user-select: none;
}

@keyframes badge-pop {
  0% { transform: scale(0.6); opacity: 0; }
  60% { transform: scale(1.15); }
  100% { transform: scale(1); }
}

@keyframes badge-glow {
  0%, 100% { box-shadow: 0 0 0 4px rgba(34, 197, 94, 0.2); }
  50% { box-shadow: 0 0 0 8px rgba(34, 197, 94, 0.35); }
}

.verified-badge svg {
  width: 18px;
  height: 18px;
}

.hero-text .subtitle {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  color: var(--accent-primary);
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.hero-text .bio {
  font-size: 1.1rem;
  max-width: 520px;
  margin-bottom: 2rem;
  color: var(--text-secondary);
}

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

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.75rem;
  border-radius: 9999px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: none;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-accent);
  color: white;
  box-shadow: 0 10px 15px -3px rgb(99 102 241 / 0.3);
}

.btn-primary:hover {
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 20px 25px -5px rgb(99 102 241 / 0.4);
}

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

.btn-outline:hover {
  background: var(--bg-secondary);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

/* Prominent Avatar with Tilt Effect */
.avatar-container {
  position: relative;
  width: 100%;
  max-width: 380px;
  margin: 0 auto;
  perspective: 1000px;
}

.avatar-wrapper {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 9999px;
  overflow: hidden;
  box-shadow: var(--shadow-strong);
  transition: transform 0.1s ease-out;
  will-change: transform;
  border: 8px solid var(--bg-secondary);
}

.avatar-wrapper::before {
  content: '';
  position: absolute;
  inset: -4px;
  border-radius: 9999px;
  background: var(--gradient-accent);
  z-index: -1;
  opacity: 0.9;
}

.avatar-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.avatar-container:hover .avatar-wrapper img {
  transform: scale(1.08);
}

.avatar-status {
  position: absolute;
  bottom: 18px;
  right: 18px;
  background: var(--accent-green);
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 14px;
  border-radius: 9999px;
  box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.2);
  display: flex;
  align-items: center;
  gap: 6px;
  z-index: 2;
}

.avatar-status::before {
  content: '';
  width: 8px;
  height: 8px;
  background: white;
  border-radius: 50%;
  animation: ping 2s cubic-bezier(0, 0, 0.2, 1) infinite;
}

@keyframes ping {
  75%, 100% { transform: scale(2); opacity: 0; }
}

/* ========================================
   STATS BAR (Quick Highlights)
   ======================================== */
.stats-bar {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  padding: 1.5rem 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  text-align: center;
}

@media (min-width: 640px) {
  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.stat-item {
  padding: 0.5rem;
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent-primary);
  line-height: 1;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* ========================================
   ABOUT SECTION
   ======================================== */
.about-content {
  max-width: 820px;
  margin: 0 auto;
  text-align: center;
}

.about-content p {
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
}

/* ========================================
   SKILLS SECTION
   ======================================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.skill-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 1.5rem;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.skill-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-strong);
}

.skill-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.skill-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(99, 102, 241, 0.1);
  color: var(--accent-primary);
  border-radius: 12px;
  font-size: 1.5rem;
}

.skill-info h4 {
  margin: 0 0 0.25rem 0;
  font-size: 1.1rem;
}

.skill-level {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.progress-bar {
  height: 8px;
  background: var(--border-color);
  border-radius: 9999px;
  overflow: hidden;
  margin-top: 0.75rem;
}

.progress-fill {
  height: 100%;
  background: var(--gradient-accent);
  border-radius: 9999px;
  width: 0;
  transition: width 1.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ========================================
   PROJECTS SECTION
   ======================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  overflow: hidden;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  transform: translateY(-12px);
  box-shadow: var(--shadow-strong);
  border-color: var(--accent-primary);
}

.project-image {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
}

.project-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.6s ease;
}

.project-card:hover .project-image img {
  transform: scale(1.12);
}

.project-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(15, 23, 42, 0.75), transparent);
  opacity: 0;
  transition: opacity 0.3s ease;
  display: flex;
  align-items: flex-end;
  padding: 1.25rem;
}

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

.project-content {
  padding: 1.5rem;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.project-content h3 {
  margin-bottom: 0.5rem;
  font-size: 1.25rem;
}

.project-content p {
  flex: 1;
  font-size: 0.95rem;
  margin-bottom: 1rem;
}

.tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.tech-tag {
  font-size: 0.75rem;
  padding: 0.25rem 0.75rem;
  background: rgba(99, 102, 241, 0.1);
  color: var(--accent-primary);
  border-radius: 9999px;
  font-weight: 500;
}

.project-actions {
  display: flex;
  gap: 0.75rem;
  margin-top: auto;
}

.project-actions .btn {
  flex: 1;
  padding: 0.6rem 1rem;
  font-size: 0.875rem;
}

/* ========================================
   MODAL
   ======================================== */
.modal {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  background: rgba(15, 23, 42, 0.85);
  backdrop-filter: blur(8px);
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--bg-card);
  border-radius: 24px;
  max-width: 820px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-strong);
  animation: modalEnter 0.3s cubic-bezier(0.32, 0.72, 0, 1);
}

@keyframes modalEnter {
  from { opacity: 0; transform: translateY(40px) scale(0.96); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.modal-header {
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-header h2 {
  margin: 0;
}

.modal-close {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: 50%;
  transition: all 0.2s ease;
}

.modal-close:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.modal-body {
  padding: 2rem;
}

.modal-body img {
  width: 100%;
  border-radius: 16px;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-soft);
}

.modal-body .tech-tags {
  margin: 1.5rem 0;
}

.modal-body p {
  font-size: 1.05rem;
}

/* ========================================
   CONTACT SECTION
   ======================================== */
.contact-container {
  max-width: 720px;
  margin: 0 auto;
}

.contact-form {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 2.5rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
  color: var(--text-primary);
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.875rem 1.25rem;
  border: 1px solid var(--border-color);
  border-radius: 12px;
  background: var(--bg-primary);
  color: var(--text-primary);
  font-size: 1rem;
  transition: all 0.2s ease;
  font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.15);
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
}

.submit-btn {
  width: 100%;
  padding: 1rem;
  font-size: 1.05rem;
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg-secondary);
  color: var(--text-primary);
  padding: 1rem 1.75rem;
  border-radius: 9999px;
  box-shadow: var(--shadow-strong);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  z-index: 3000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  border: 1px solid var(--border-color);
}

.toast.show {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(-10px);
}

.toast.success {
  border-left: 5px solid var(--accent-green);
}

/* ========================================
   FOOTER
   ======================================== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  text-align: center;
}

.social-links {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  margin-bottom: 2rem;
}

.social-links a {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 50%;
  font-size: 1.25rem;
  color: var(--text-secondary);
  transition: all 0.3s ease;
}

.social-links a:hover {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  transform: translateY(-4px);
}

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

/* Back to Top */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 52px;
  height: 52px;
  background: var(--accent-primary);
  color: white;
  border: none;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  box-shadow: var(--shadow-strong);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-4px) scale(1.05);
}

/* ========================================
   RESPONSIVE STYLES
   ======================================== */
@media (max-width: 1024px) {
  .nav-links {
    display: none;
  }
  
  .hamburger {
    display: flex;
  }
}

@media (max-width: 768px) {
  .section {
    padding: 4rem 0;
  }
  
  .hero {
    min-height: auto;
    padding: 6rem 0 4rem;
  }
  
  .avatar-container {
    max-width: 280px;
    margin-top: 2rem;
  }
  
  .project-card {
    max-width: 100%;
  }
  
  .contact-form {
    padding: 1.75rem;
  }
}

@media (max-width: 480px) {
  .cta-buttons {
    flex-direction: column;
  }
  
  .btn {
    width: 100%;
    justify-content: center;
  }
  
  .stats-grid {
    grid-template-columns: 1fr 1fr;
  }
}

/* Accessibility & Performance */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Custom Scrollbar (Modern) */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}
::-webkit-scrollbar-thumb {
  background: var(--accent-primary);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: #4f46e5;
}