/* =========================================
   CSS Custom Properties (Design Tokens)
   ========================================= */
:root {
  /* Colors */
  --color-bg: #0f0f14;
  --color-bg-secondary: #16161d;
  --color-bg-card: #1c1c26;
  --color-bg-card-hover: #22222e;
  --color-sidebar: #12121a;
  --color-primary: #0ea5e9;
  --color-primary-light: #38bdf8;
  --color-primary-dark: #0284c7;
  --color-accent: #10b981;
  --color-text: #e4e4ed;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-border: #1e293b;
  --color-border-light: #334155;
  --color-highlight: rgba(14, 165, 233, 0.1);
  --color-success: #10b981;
  --color-warning: #f59e0b;

  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --sidebar-width: 280px;
  --section-padding: 80px;

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 20px rgba(14, 165, 233, 0.3);
}

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

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

body {
  font-family: var(--font-primary);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-primary-light);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

ul {
  list-style: none;
}

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

::selection {
  background: var(--color-primary);
  color: #fff;
}

/* =========================================
   Scrollbar Styling
   ========================================= */
::-webkit-scrollbar {
  width: 6px;
}

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

::-webkit-scrollbar-thumb {
  background: var(--color-border-light);
  border-radius: var(--radius-full);
}

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

/* =========================================
   Sidebar Navigation
   ========================================= */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--color-sidebar);
  border-right: 1px solid var(--color-border);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal);
}

.sidebar-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: 40px 30px;
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 50px;
}

.logo-symbol {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.2rem;
  color: #fff;
}

.sidebar-logo .logo-text {
  font-size: 1.1rem;
  font-weight: 300;
  color: var(--color-text);
}

.sidebar-logo .logo-text strong {
  font-weight: 700;
}

.sidebar-nav {
  flex: 1;
}

.sidebar-nav li {
  margin-bottom: 4px;
}

.sidebar-nav .nav-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition-fast);
  position: relative;
}

.sidebar-nav .nav-link i {
  width: 20px;
  text-align: center;
  font-size: 0.9rem;
}

.sidebar-nav .nav-link:hover {
  color: var(--color-text);
  background: var(--color-highlight);
}

.sidebar-nav .nav-link.active {
  color: var(--color-primary-light);
  background: var(--color-highlight);
}

.sidebar-nav .nav-link.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 24px;
  background: var(--color-primary);
  border-radius: var(--radius-full);
}

/* =========================================
   Language Switcher
   ========================================= */
.lang-switcher {
  display: flex;
  gap: 4px;
  padding: 3px;
  background: var(--color-highlight);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  margin-bottom: 16px;
}

.lang-btn {
  background: none;
  border: none;
  color: var(--color-text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  font-family: var(--font-mono);
  padding: 6px 12px;
  border-radius: 4px;
  cursor: pointer;
  transition: all var(--transition-fast);
  letter-spacing: 0.5px;
}

.lang-btn:hover {
  color: var(--color-text);
}

.lang-btn.active {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(14, 165, 233, 0.3);
}

.lang-switcher-mobile {
  margin-bottom: 0;
}

.mobile-header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.sidebar-social {
  display: flex;
  gap: 12px;
  padding-top: 20px;
  border-top: 1px solid var(--color-border);
}

.sidebar-social a {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: 1rem;
  transition: all var(--transition-fast);
}

.sidebar-social a:hover {
  color: var(--color-primary-light);
  border-color: var(--color-primary);
  background: var(--color-highlight);
}

/* =========================================
   Mobile Header
   ========================================= */
.mobile-header {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  background: rgba(15, 15, 20, 0.95);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  z-index: 999;
  padding: 0 20px;
  align-items: center;
  justify-content: space-between;
}

.mobile-header .logo-text {
  font-size: 1.2rem;
  font-weight: 300;
  color: var(--color-text);
}

.mobile-header .logo-text strong {
  font-weight: 800;
  color: var(--color-primary-light);
}

.menu-toggle {
  background: none;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  font-size: 1.2rem;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.menu-toggle:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-light);
}

/* =========================================
   Main Content
   ========================================= */
.main-content {
  margin-left: var(--sidebar-width);
  min-height: 100vh;
}

.section {
  padding: var(--section-padding) 60px;
  max-width: 1200px;
}

/* =========================================
   Buttons
   ========================================= */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-family: var(--font-primary);
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all var(--transition-normal);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
  box-shadow: 0 4px 15px rgba(14, 165, 233, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(14, 165, 233, 0.5);
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border-light);
}

.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-light);
  background: var(--color-highlight);
}

/* =========================================
   Section Headers
   ========================================= */
.section-header {
  margin-bottom: 50px;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 8px;
}

.section-subtitle {
  font-size: 1rem;
  color: var(--color-primary-light);
  font-weight: 500;
}

/* =========================================
   About / Hero Section
   ========================================= */
.section-about {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
}

.hero-content {
  margin-bottom: 60px;
}

.hero-role {
  font-size: 1.3rem;
  color: var(--color-accent);
  font-weight: 500;
  margin-bottom: 24px;
  font-family: var(--font-mono);
}

.hero-bio {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 680px;
  line-height: 1.8;
  margin-bottom: 32px;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.stat-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  text-align: center;
  transition: all var(--transition-normal);
}

.stat-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.stat-number {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-primary-light);
  font-family: var(--font-mono);
}

.stat-plus {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary-light);
}

.stat-label {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: 4px;
  font-weight: 500;
}

/* =========================================
   Resume Section
   ========================================= */
.resume-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  margin-bottom: 60px;
}

.resume-category-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 30px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.resume-category-title i {
  color: var(--color-primary-light);
}

/* Timeline */
.timeline {
  position: relative;
  padding-left: 28px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  padding-bottom: 32px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -33px;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 2px solid var(--color-primary);
}

.timeline-date {
  font-size: 0.8rem;
  color: var(--color-primary-light);
  font-weight: 600;
  font-family: var(--font-mono);
  letter-spacing: 0.5px;
}

.timeline-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 6px 0 4px;
}

.timeline-company {
  font-size: 0.9rem;
  color: var(--color-accent);
  font-weight: 500;
  display: block;
  margin-bottom: 0;
  text-decoration: none;
  transition: color var(--transition-fast);
}

.timeline-degree {
  display: block;
  font-size: 0.8rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-top: 2px;
  margin-bottom: 0;
}

a.timeline-company i {
  font-size: 0.7rem;
  margin-left: 4px;
  opacity: 0.5;
  transition: opacity var(--transition-fast);
}

a.timeline-company:hover {
  color: var(--color-primary-light);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a.timeline-company:hover i {
  opacity: 1;
}

.timeline-location {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 10px;
}

.timeline-location i {
  font-size: 0.7rem;
  margin-right: 4px;
}

.timeline-item p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.timeline-list {
  list-style: none;
  padding: 0;
}

.timeline-list li {
  font-size: 0.88rem;
  color: var(--color-text-secondary);
  padding: 3px 0;
  padding-left: 18px;
  position: relative;
  line-height: 1.6;
}

.timeline-list li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-weight: bold;
}

/* Skills */
.skills-section {
  margin-bottom: 60px;
}

.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
}

.skills-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.skill-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 20px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.skill-item:hover {
  border-color: var(--color-primary);
  transform: translateX(4px);
}

.skill-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
}

.skill-level {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.skill-level.expert {
  background: rgba(16, 185, 129, 0.15);
  color: var(--color-accent);
}

.skill-level.intermediate {
  background: rgba(245, 158, 11, 0.15);
  color: var(--color-warning);
}

/* Soft Skills Tags */
.soft-skills-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.soft-skill-tag {
  padding: 10px 20px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.soft-skill-tag:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-light);
  background: var(--color-highlight);
}

/* Certificates */
.certificates-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}

.certificate-card {
  display: block;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all var(--transition-normal);
  text-decoration: none;
  color: inherit;
  cursor: pointer;
  position: relative;
}

.certificate-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
  color: inherit;
}

.cert-view {
  position: absolute;
  top: 16px;
  right: 16px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  opacity: 0;
  transition: opacity var(--transition-fast), color var(--transition-fast);
}

.certificate-card:hover .cert-view {
  opacity: 1;
  color: var(--color-primary-light);
}

.certificate-card.highlight {
  border-color: var(--color-accent);
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.05), transparent);
}

.certificate-card.highlight:hover {
  border-color: var(--color-accent);
  box-shadow: 0 0 20px rgba(16, 185, 129, 0.15);
}

.cert-icon {
  font-size: 1.5rem;
  color: var(--color-primary-light);
  margin-bottom: 12px;
}

.certificate-card.highlight .cert-icon {
  color: var(--color-accent);
}

.certificate-card h4 {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
  line-height: 1.4;
}

.cert-date {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* =========================================
   Portfolio Section
   ========================================= */
.portfolio-filters {
  display: flex;
  gap: 8px;
  margin-bottom: 30px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 8px 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--color-text-secondary);
  font-family: var(--font-primary);
  font-size: 0.88rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-light);
}

.filter-btn.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 20px;
}

.portfolio-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px;
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.portfolio-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.portfolio-card.hidden {
  display: none;
}

.portfolio-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 20px;
}

.portfolio-icon {
  font-size: 1.8rem;
  color: var(--color-primary-light);
}

.portfolio-links a {
  color: var(--color-text-muted);
  font-size: 1.1rem;
  transition: color var(--transition-fast);
}

.portfolio-links a:hover {
  color: var(--color-accent);
}

.portfolio-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 10px;
}

.portfolio-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
  flex: 1;
}

.portfolio-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.portfolio-tags span {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  padding: 3px 10px;
  background: var(--color-highlight);
  color: var(--color-primary-light);
  border-radius: var(--radius-full);
  font-weight: 500;
}

.portfolio-date {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* =========================================
   Seminars Section
   ========================================= */
.seminar-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 32px;
  position: relative;
  transition: all var(--transition-normal);
}

.seminar-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.seminar-badge {
  display: inline-block;
  padding: 4px 14px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
  font-size: 0.78rem;
  font-weight: 700;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 16px;
}

.seminar-date {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 10px;
  display: block;
}

.seminar-date i {
  margin-right: 6px;
}

.seminar-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 12px;
}

.seminar-desc {
  font-size: 0.93rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 16px;
}

.seminar-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.seminar-tags span {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  padding: 3px 10px;
  background: var(--color-highlight);
  color: var(--color-primary-light);
  border-radius: var(--radius-full);
  font-weight: 500;
}

/* =========================================
   Contact Section
   ========================================= */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.5fr;
  gap: 50px;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.contact-icon {
  width: 48px;
  height: 48px;
  background: var(--color-highlight);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary-light);
  font-size: 1rem;
  flex-shrink: 0;
}

.contact-text h4 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 4px;
}

.contact-text a,
.contact-text p {
  font-size: 1rem;
  color: var(--color-text);
}

.contact-text a:hover {
  color: var(--color-primary-light);
}

.contact-socials {
  display: flex;
  gap: 12px;
  margin-top: 8px;
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.social-link:hover {
  border-color: var(--color-primary);
  color: var(--color-primary-light);
  background: var(--color-highlight);
}

/* Contact Form */
.contact-form-wrapper h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 24px;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 14px 18px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-family: var(--font-primary);
  font-size: 0.95rem;
  transition: all var(--transition-fast);
  outline: none;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--color-text-muted);
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.15);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

.btn-submit {
  align-self: flex-start;
}

.btn-submit.loading {
  pointer-events: none;
  opacity: 0.7;
}

.form-status {
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  display: none;
}

.form-status.success {
  display: block;
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid var(--color-accent);
  color: var(--color-accent);
}

.form-status.error {
  display: block;
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid #ef4444;
  color: #ef4444;
}

/* =========================================
   Footer
   ========================================= */
.footer {
  padding: 30px 60px;
  border-top: 1px solid var(--color-border);
}

.footer p {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

/* =========================================
   Back to Top Button
   ========================================= */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 44px;
  height: 44px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all var(--transition-normal);
  z-index: 900;
  box-shadow: var(--shadow-md);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

/* =========================================
   Scroll Progress Bar
   ========================================= */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  z-index: 9999;
  transition: width 0.1s linear;
  box-shadow: 0 0 10px var(--color-primary);
}

/* =========================================
   Particle Canvas (Hero)
   ========================================= */
.particle-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
}

.section-about .hero-content,
.section-about .stats-grid {
  position: relative;
  z-index: 1;
}

/* =========================================
   Typing Cursor
   ========================================= */
.typing-cursor {
  font-weight: 300;
  animation: blink 0.8s step-end infinite;
  color: var(--color-primary-light);
}

@keyframes blink {
  50% { opacity: 0; }
}

/* =========================================
   Animated Gradient Hero Name
   ========================================= */
.hero-name {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 12px;
  background: linear-gradient(
    135deg,
    var(--color-text) 0%,
    var(--color-primary-light) 25%,
    var(--color-accent) 50%,
    var(--color-primary-light) 75%,
    var(--color-text) 100%
  );
  background-size: 300% 300%;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: gradientShift 6s ease infinite;
}

@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

/* =========================================
   Mouse-Follow Glow on Cards
   ========================================= */
.glow-card {
  position: relative;
  overflow: hidden;
}

.glow-card::before {
  content: '';
  position: absolute;
  top: var(--glow-y, -100px);
  left: var(--glow-x, -100px);
  width: 250px;
  height: 250px;
  background: radial-gradient(
    circle,
    rgba(14, 165, 233, 0.15) 0%,
    transparent 70%
  );
  border-radius: 50%;
  transform: translate(-50%, -50%);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s ease;
  z-index: 0;
}

.glow-card:hover::before {
  opacity: 1;
}

.glow-card > * {
  position: relative;
  z-index: 1;
}

/* =========================================
   3D Tilt Effect on Portfolio Cards
   ========================================= */
.portfolio-card.glow-card {
  transform-style: preserve-3d;
  transition: all var(--transition-normal), transform 0.15s ease;
}

/* =========================================
   Staggered Grid Entrance
   ========================================= */
.portfolio-grid .portfolio-card,
.certificates-grid .certificate-card,
.stats-grid .stat-card {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.5s ease, transform 0.5s ease, border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.portfolio-grid .portfolio-card.stagger-visible,
.certificates-grid .certificate-card.stagger-visible,
.stats-grid .stat-card.stagger-visible {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================
   Interactive Section Divider
   ========================================= */
.section::after {
  content: '';
  display: block;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-full);
  margin-top: 60px;
  opacity: 0.4;
}

.section:last-of-type::after {
  display: none;
}

/* =========================================
   Pulse Effect on Hero Greeting
   ========================================= */
.hero-greeting {
  display: inline-block;
  font-size: 1rem;
  color: var(--color-primary-light);
  font-weight: 500;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 12px;
  position: relative;
}

.hero-greeting::before {
  content: '';
  display: inline-block;
  width: 8px;
  height: 8px;
  background: var(--color-accent);
  border-radius: 50%;
  margin-right: 10px;
  animation: pulse 2s ease-in-out infinite;
  vertical-align: middle;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.5); }
  50% { box-shadow: 0 0 0 8px rgba(16, 185, 129, 0); }
}

/* =========================================
   Animations
   ========================================= */
.animate-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Stagger children */
.animate-in:nth-child(2) { transition-delay: 0.1s; }
.animate-in:nth-child(3) { transition-delay: 0.2s; }
.animate-in:nth-child(4) { transition-delay: 0.3s; }
.animate-in:nth-child(5) { transition-delay: 0.4s; }

/* =========================================
   Responsive Design
   ========================================= */

/* Tablet */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .mobile-header {
    display: flex;
  }

  .main-content {
    margin-left: 0;
    padding-top: 60px;
  }

  .section {
    padding: 60px 40px;
  }

  .hero-name {
    font-size: 2.8rem;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .resume-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .skills-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .portfolio-grid {
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  }
}

/* Mobile */
@media (max-width: 640px) {
  .section {
    padding: 50px 20px;
  }

  .hero-name {
    font-size: 2.2rem;
  }

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

  .hero-bio {
    font-size: 0.95rem;
  }

  .hero-buttons {
    flex-direction: column;
  }

  .hero-buttons .btn {
    text-align: center;
    justify-content: center;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .stat-card {
    padding: 20px 16px;
  }

  .stat-number {
    font-size: 1.8rem;
  }

  .section-title {
    font-size: 1.8rem;
  }

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

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

  .contact-socials {
    flex-direction: column;
  }

  .footer {
    padding: 20px;
  }
}

/* Overlay for mobile menu */
.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: 999;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.sidebar-overlay.active {
  display: block;
}

/* =========================================
   Lightbox Modal
   ========================================= */
.lightbox-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.85);
  z-index: 2000;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  animation: lightboxFadeIn 0.25s ease;
}

.lightbox-overlay.active {
  display: flex;
}

.lightbox-content {
  max-width: 90vw;
  max-height: 85vh;
  position: relative;
}

.lightbox-content img {
  max-width: 100%;
  max-height: 85vh;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  object-fit: contain;
  animation: lightboxZoomIn 0.3s ease;
}

.lightbox-close {
  position: absolute;
  top: 20px;
  right: 24px;
  width: 44px;
  height: 44px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-sm);
  color: #fff;
  font-size: 1.2rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  z-index: 2001;
}

.lightbox-close:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: scale(1.1);
}

@keyframes lightboxFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes lightboxZoomIn {
  from { opacity: 0; transform: scale(0.9); }
  to { opacity: 1; transform: scale(1); }
}