/* ==========================================================================
   STYLE.CSS — CORE DESIGN TOKENS, RESETS & FOUNDATION
   Project: Personal Portfolio Website — Shanto Paul (DIU)
   Architecture: UI/UX Pro Max Bento Box + AI-Native Interface
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. Google Fonts Imports
   -------------------------------------------------------------------------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500;600&family=Space+Grotesk:wght@500;600;700&display=swap');

/* --------------------------------------------------------------------------
   2. Design Tokens & CSS Custom Properties
   -------------------------------------------------------------------------- */
:root {
  /* Color System — Light Theme (Default) */
  --primary: #2563EB;
  --primary-dark: #1D4ED8;
  --primary-light: #DBEAFE;
  --primary-rgb: 37, 99, 235;

  --secondary: #10B981;
  --secondary-light: #D1FAE5;
  --accent: #7C3AED;
  --accent-cyan: #0891B2;
  --accent-light: #EDE9FE;

  --bg-primary: #FFFFFF;
  --bg-secondary: #F8FAFC;
  --bg-tertiary: #F1F5F9;
  --surface: #FFFFFF;
  --surface-alt: #F1F5F9;

  --text-primary: #1E293B;
  --text-secondary: #64748B;
  --text-muted: #94A3B8;

  --border: #E2E8F0;
  --border-focus: #2563EB;

  --error: #EF4444;
  --warning: #F59E0B;
  --success: #10B981;
  --info: #0284C7;

  /* Typography Stacks */
  --font-heading: 'Space Grotesk', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

  /* Spacing Scale (8-point grid) */
  --space-2xs: 0.125rem; /* 2px */
  --space-xs:  0.25rem;  /* 4px */
  --space-sm:  0.5rem;   /* 8px */
  --space-md:  1.0rem;   /* 16px */
  --space-lg:  1.5rem;   /* 24px */
  --space-xl:  2.0rem;   /* 32px */
  --space-2xl: 3.0rem;   /* 48px */
  --space-3xl: 4.0rem;   /* 64px */
  --space-4xl: 6.0rem;   /* 96px */

  /* Border Radius Tokens */
  --radius-xs:   0.25rem; /* 4px */
  --radius-sm:   0.375rem;/* 6px */
  --radius-md:   0.5rem;  /* 8px */
  --radius-lg:   0.75rem; /* 12px */
  --radius-xl:   1.0rem;  /* 16px */
  --radius-2xl:  1.5rem;  /* 24px */
  --radius-full: 9999px;

  /* Elevation Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.03);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.10), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --shadow-primary-glow: 0 0 25px rgba(37, 99, 235, 0.25);
  --shadow-accent-glow:  0 0 25px rgba(124, 58, 237, 0.25);

  /* Gradients */
  --gradient-hero: linear-gradient(135deg, #2563EB 0%, #7C3AED 100%);
  --gradient-card-hover: linear-gradient(135deg, rgba(37, 99, 235, 0.05) 0%, rgba(124, 58, 237, 0.05) 100%);
  --gradient-chatbot: linear-gradient(135deg, #2563EB 0%, #7C3AED 100%);
  --gradient-border: linear-gradient(135deg, #2563EB, #0891B2, #7C3AED);

  /* Transitions & Animation Easings */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Layout Standards */
  --navbar-height: 70px;
  --container-max-width: 1200px;
}

/* --------------------------------------------------------------------------
   3. Dark Theme Tokens
   -------------------------------------------------------------------------- */
[data-theme='dark'] {
  --primary: #3B82F6;
  --primary-dark: #60A5FA;
  --primary-light: #1E3A5F;
  --primary-rgb: 59, 130, 246;

  --secondary: #10B981;
  --secondary-light: #064E3B;
  --accent: #8B5CF6;
  --accent-cyan: #06B6D4;
  --accent-light: #2E1065;

  --bg-primary: #0F172A;
  --bg-secondary: #1E293B;
  --bg-tertiary: #334155;
  --surface: #1E293B;
  --surface-alt: #334155;

  --text-primary: #F1F5F9;
  --text-secondary: #94A3B8;
  --text-muted: #64748B;

  --border: #334155;
  --border-focus: #3B82F6;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
  --shadow-primary-glow: 0 0 30px rgba(59, 130, 246, 0.35);
  --shadow-accent-glow:  0 0 30px rgba(139, 92, 246, 0.35);

  --gradient-card-hover: linear-gradient(135deg, rgba(59, 130, 246, 0.10) 0%, rgba(139, 92, 246, 0.10) 100%);
}

/* --------------------------------------------------------------------------
   4. Universal CSS Reset & Base Rules
   -------------------------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--navbar-height) + 1rem);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  min-height: 100dvh;
  overflow-x: hidden;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* --------------------------------------------------------------------------
   5. Accessible Focus Ring & Skip Link
   -------------------------------------------------------------------------- */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: var(--space-md);
  background: var(--primary);
  color: #FFFFFF;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  font-weight: 600;
  z-index: 9999;
  text-decoration: none;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-md);
}

/* --------------------------------------------------------------------------
   6. Typography Hierarchy
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--text-primary);
  font-weight: 700;
  line-height: 1.2;
  text-wrap: balance;
  overflow-wrap: break-word;
}

h1 {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  letter-spacing: -0.025em;
}

h2 {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  letter-spacing: -0.02em;
}

h3 {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  letter-spacing: -0.015em;
}

h4 {
  font-size: 1.25rem;
}

p {
  color: var(--text-secondary);
  line-height: 1.7;
  text-wrap: pretty;
  max-width: 70ch;
}

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

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

code, pre {
  font-family: var(--font-mono);
}

/* Gradient Text Mask */
.text-gradient {
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* --------------------------------------------------------------------------
   7. Layout & Container Architecture
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-md);
  padding-right: var(--space-md);
}

.section {
  padding: var(--space-4xl) 0;
  position: relative;
}

.section-alt {
  background-color: var(--bg-secondary);
}

.section-header {
  text-align: center;
  max-width: 650px;
  margin: 0 auto var(--space-3xl) auto;
}

.section-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 600;
  background: var(--primary-light);
  color: var(--primary);
  margin-bottom: var(--space-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

[data-theme='dark'] .section-badge {
  background: rgba(59, 130, 246, 0.15);
  color: var(--primary);
}

.section-title {
  margin-bottom: var(--space-sm);
}

.section-subtitle {
  color: var(--text-secondary);
  font-size: 1.05rem;
  margin: 0 auto;
}

/* --------------------------------------------------------------------------
   7.1 Navigation Bar Component (Glassmorphism & Sticky Header)
   -------------------------------------------------------------------------- */
.navbar {
  position: sticky;
  top: 0;
  width: 100%;
  height: var(--navbar-height);
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: background-color var(--transition-normal), 
              box-shadow var(--transition-normal),
              border-color var(--transition-normal);
}

[data-theme='dark'] .navbar {
  background-color: rgba(15, 23, 42, 0.85);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
  border-bottom-color: rgba(37, 99, 235, 0.2);
}

.navbar-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  text-decoration: none;
}

.nav-brand-text {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
}

.nav-brand:hover .text-gradient {
  filter: brightness(1.15);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  list-style: none;
}

.nav-link {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  position: relative;
  padding: 0.35rem 0;
  transition: color var(--transition-fast);
}

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

.nav-link.active {
  color: var(--primary);
  font-weight: 600;
}

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

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

.btn-icon {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
  background: var(--bg-tertiary);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background: var(--surface-alt);
  color: var(--primary);
  border-color: var(--primary);
  transform: scale(1.05);
}

/* --------------------------------------------------------------------------
   7.2 Hero Section Architecture (Ambient Mesh & Layout)
   -------------------------------------------------------------------------- */
.hero-section {
  padding-top: calc(var(--space-2xl) + 1rem);
  padding-bottom: var(--space-4xl);
  position: relative;
  overflow: hidden;
}

/* Ambient Background Radial Glows */
.hero-section::before {
  content: '';
  position: absolute;
  top: -10%;
  right: -5%;
  width: 550px;
  height: 550px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(37, 99, 235, 0.15) 0%, rgba(124, 58, 237, 0.08) 45%, transparent 70%);
  filter: blur(60px);
  pointer-events: none;
  z-index: 0;
}

[data-theme='dark'] .hero-section::before {
  background: radial-gradient(circle, rgba(59, 130, 246, 0.22) 0%, rgba(139, 92, 246, 0.14) 45%, transparent 70%);
}

.hero-section::after {
  content: '';
  position: absolute;
  bottom: 0%;
  left: -5%;
  width: 450px;
  height: 450px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(16, 185, 129, 0.12) 0%, rgba(8, 145, 178, 0.06) 50%, transparent 70%);
  filter: blur(50px);
  pointer-events: none;
  z-index: 0;
}

/* Hero Typewriter Subtitle Container (Zero CLS) */
.hero-typewriter-container {
  min-height: 2.2rem;
  display: flex;
  align-items: center;
  margin-bottom: var(--space-sm);
  font-family: var(--font-heading);
  font-size: clamp(1.15rem, 2.5vw, 1.45rem);
  font-weight: 600;
  color: var(--primary);
}

/* Hero Social Icons Row */
.hero-socials {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-top: var(--space-lg);
}

.hero-social-btn {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.hero-social-btn:hover {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  box-shadow: var(--shadow-sm), var(--shadow-primary-glow);
  transform: translateY(-3px);
}

/* Hero Profile Avatar Container & Floating Badges */
.hero-avatar-card {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
}

.hero-avatar-ring {
  position: relative;
  width: 220px;
  height: 220px;
  border-radius: 50%;
  padding: 5px;
  background: var(--gradient-border);
  box-shadow: var(--shadow-xl), var(--shadow-primary-glow);
}

.hero-avatar-img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  background: var(--bg-primary);
  display: block;
}

/* Floating Glassmorphism Badges */
.hero-floating-badge {
  position: absolute;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  padding: 0.45rem 0.9rem;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-primary);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  z-index: 2;
  white-space: nowrap;
}

[data-theme='dark'] .hero-floating-badge {
  background: rgba(30, 41, 59, 0.88);
  border-color: var(--border);
}

.badge-pos-top-right {
  top: 15px;
  right: 0px;
}

.badge-pos-bottom-left {
  bottom: 20px;
  left: 0px;
}

/* --------------------------------------------------------------------------
   7.3 About Me Section Architecture
   -------------------------------------------------------------------------- */
.about-grid {
  display: grid;
  grid-template-columns: 360px 1fr;
  gap: var(--space-2xl);
  align-items: start;
}

.about-profile-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-md);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.about-profile-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 80px;
  background: var(--gradient-hero);
  opacity: 0.15;
}

.about-avatar-wrap {
  position: relative;
  width: 140px;
  height: 140px;
  margin: var(--space-md) auto var(--space-md);
  border-radius: 50%;
  padding: 4px;
  background: var(--gradient-border);
  box-shadow: var(--shadow-lg), var(--shadow-primary-glow);
}

.about-avatar-img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  background: var(--bg-primary);
  display: block;
}

.about-facts-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  margin-top: var(--space-lg);
  text-align: left;
}

.about-fact-item {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 0.65rem 0.85rem;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  border: 1px solid var(--border);
  color: var(--text-secondary);
}

.about-fact-item i {
  color: var(--primary);
  font-size: 1rem;
  min-width: 20px;
  text-align: center;
}

.about-fact-item strong {
  color: var(--text-primary);
  font-weight: 600;
}

.about-bio-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.about-career-box {
  background: rgba(37, 99, 235, 0.06);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-md) var(--space-lg);
}

[data-theme='dark'] .about-career-box {
  background: rgba(37, 99, 235, 0.12);
}

.about-stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  margin-top: var(--space-xs);
}

.stat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  text-align: center;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.stat-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
}

.stat-card-value {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  line-height: 1.1;
}

.stat-card-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: var(--space-2xs);
  font-weight: 500;
}

/* --------------------------------------------------------------------------
   7.4 Technical Skills Matrix Architecture
   -------------------------------------------------------------------------- */
.skills-nav-tabs {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-2xl);
}

.skill-tab-btn {
  padding: 0.5rem 1.1rem;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.skill-tab-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--primary);
}

.skill-tab-btn.active {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  box-shadow: var(--shadow-sm), var(--shadow-primary-glow);
}

.skills-categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-xl);
}

.skill-cat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  transition: transform var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

.skill-cat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border);
  padding-bottom: var(--space-sm);
}

.skill-cat-title {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

.skill-cat-title i {
  color: var(--primary);
  font-size: 1.25rem;
}

.skills-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.skill-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 0.9rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

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

.skill-name-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-primary);
}

.skill-icon {
  font-size: 1.15rem;
  width: 22px;
  text-align: center;
  color: var(--primary);
}

.skill-level-badge {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-full);
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-secondary);
}

.skill-level-badge.advanced {
  background: rgba(37, 99, 235, 0.12);
  color: var(--primary);
  border-color: rgba(37, 99, 235, 0.3);
}

.skill-level-badge.proficient {
  background: rgba(16, 185, 129, 0.12);
  color: var(--secondary);
  border-color: rgba(16, 185, 129, 0.3);
}

.skill-level-badge.intermediate {
  background: rgba(124, 58, 237, 0.12);
  color: var(--accent);
  border-color: rgba(124, 58, 237, 0.3);
}

.skill-level-badge.foundation {
  background: var(--bg-secondary);
  color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   7.5 Education Timeline Architecture
   -------------------------------------------------------------------------- */
.timeline {
  position: relative;
  max-width: 860px;
  margin: var(--space-xl) auto 0;
  padding: var(--space-md) 0;
}

.timeline::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 28px;
  width: 3px;
  background: var(--gradient-hero);
  border-radius: var(--radius-full);
  opacity: 0.7;
}

.timeline-item {
  position: relative;
  padding-left: 72px;
  margin-bottom: var(--space-2xl);
}

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

.timeline-marker {
  position: absolute;
  left: 17px;
  top: 20px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--surface);
  border: 3px solid var(--primary);
  box-shadow: 0 0 14px var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
  transition: transform var(--transition-fast), background-color var(--transition-fast);
}

.timeline-item:hover .timeline-marker {
  transform: scale(1.2);
  background: var(--primary);
}

.timeline-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.timeline-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md), var(--shadow-primary-glow);
}

.timeline-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-sm);
}

.timeline-degree {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.timeline-institution {
  font-size: 1rem;
  font-weight: 600;
  color: var(--primary);
  margin-top: 2px;
}

.timeline-period {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.3rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 600;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text-secondary);
}

.timeline-courses-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-top: var(--space-md);
  margin-bottom: var(--space-xs);
}

.timeline-course-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

/* --------------------------------------------------------------------------
   7.6 Experience & Achievements Section Architecture
   -------------------------------------------------------------------------- */
.experience-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: var(--space-xl);
  max-width: 1040px;
  margin: var(--space-xl) auto 0;
}

.exp-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: var(--space-md);
  transition: transform var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

.exp-badge-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.exp-role-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: var(--space-xs);
}

.exp-org-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--primary);
}

.exp-desc {
  font-size: 0.925rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.exp-highlights-list {
  list-style: none;
  padding-left: 0;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.exp-highlights-list li {
  font-size: 0.875rem;
  color: var(--text-secondary);
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}

.exp-highlights-list li i {
  color: var(--secondary);
  margin-top: 3px;
  flex-shrink: 0;
}

.exp-tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  padding-top: var(--space-sm);
  border-top: 1px solid var(--border);
}

/* --------------------------------------------------------------------------
   8. Button Component Specifications
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 0.75rem 1.5rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  min-height: 44px; /* WCAG touch target */
  min-width: 44px;
  transition: transform var(--transition-fast), 
              box-shadow var(--transition-fast), 
              background-color var(--transition-fast), 
              border-color var(--transition-fast);
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--primary);
  color: #FFFFFF;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background: var(--primary-dark);
  color: #FFFFFF;
  box-shadow: var(--shadow-md), var(--shadow-primary-glow);
  transform: translateY(-2px);
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

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

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

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

.btn-gradient {
  background: var(--gradient-hero);
  color: #FFFFFF;
  box-shadow: var(--shadow-md);
}

.btn-gradient:hover {
  box-shadow: var(--shadow-lg), var(--shadow-accent-glow);
  transform: translateY(-2px);
}

/* --------------------------------------------------------------------------
   9. Bento Box Grid System (UI/UX Pro Max)
   -------------------------------------------------------------------------- */
.bento-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: minmax(180px, auto);
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.bento-item--col-1 { grid-column: span 1; }
.bento-item--col-2 { grid-column: span 2; }
.bento-item--col-3 { grid-column: span 3; }
.bento-item--col-4 { grid-column: span 4; }

.bento-item--row-1 { grid-row: span 1; }
.bento-item--row-2 { grid-row: span 2; }

.bento-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-lg);
  overflow: hidden;
  transition: transform var(--transition-normal), 
              box-shadow var(--transition-normal), 
              border-color var(--transition-normal);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.bento-card:hover {
  transform: translateY(-4px) scale(1.01);
  box-shadow: var(--shadow-xl), var(--shadow-primary-glow);
  border-color: var(--primary);
}

/* --------------------------------------------------------------------------
   10. Badges & Tags
   -------------------------------------------------------------------------- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 500;
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.badge:hover {
  background-color: var(--primary-light);
  color: var(--primary);
  border-color: var(--primary);
}

.badge-verified {
  background-color: rgba(16, 185, 129, 0.12);
  color: var(--secondary);
  border-color: rgba(16, 185, 129, 0.3);
}

.badge-featured {
  background: var(--gradient-hero);
  color: #FFFFFF;
  font-weight: 600;
  border: none;
  box-shadow: var(--shadow-sm);
}

.badge-category {
  background: rgba(37, 99, 235, 0.12);
  color: var(--primary);
  border-color: rgba(37, 99, 235, 0.3);
  font-weight: 600;
}

/* --------------------------------------------------------------------------
   11. Projects Showcase Section Architecture
   -------------------------------------------------------------------------- */
.project-filters {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: var(--space-xs);
  flex-wrap: wrap;
  margin-bottom: var(--space-2xl);
}

.project-filter-btn {
  padding: 0.5rem 1.15rem;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.project-filter-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--primary);
}

.project-filter-btn.active {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  box-shadow: var(--shadow-sm), var(--shadow-primary-glow);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: var(--space-xl);
}

.project-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), 
              box-shadow var(--transition-fast), 
              border-color var(--transition-fast);
  padding: 0;
}

.project-card:hover {
  transform: translateY(-6px);
  border-color: var(--primary);
  box-shadow: var(--shadow-xl), var(--shadow-primary-glow);
}

.project-card-image-wrap {
  position: relative;
  width: 100%;
  height: 210px;
  overflow: hidden;
  background: var(--bg-tertiary);
}

.project-card-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-normal);
  display: block;
}

.project-card:hover .project-card-image {
  transform: scale(1.06);
}

.project-card-image-wrap .badge-featured {
  position: absolute;
  top: 12px;
  right: 12px;
  z-index: 2;
}

.project-card-body {
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  flex-grow: 1;
}

.project-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
  margin-top: 4px;
}

.project-card-desc {
  font-size: 0.925rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-top: var(--space-2xs);
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: var(--space-sm);
}

.project-card-footer {
  padding: var(--space-md) var(--space-lg);
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: var(--space-sm);
}

.btn-sm {
  padding: 0.45rem 0.9rem;
  font-size: 0.85rem;
  min-height: 36px;
  border-radius: var(--radius-sm);
}

.no-projects {
  grid-column: 1 / -1;
  text-align: center;
  padding: var(--space-3xl) var(--space-md);
  color: var(--text-muted);
  font-size: 1.05rem;
}

/* --------------------------------------------------------------------------
   12. Contact Section Architecture
   -------------------------------------------------------------------------- */
.contact-grid {
  display: grid;
  grid-template-columns: 360px 1fr;
  gap: var(--space-2xl);
  align-items: start;
}

.contact-info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.contact-info-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.contact-info-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
}

.contact-info-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-lg);
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.15rem;
  flex-shrink: 0;
  transition: all var(--transition-fast);
}

.contact-info-item:hover .contact-info-icon {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  transform: scale(1.05);
}

.contact-info-label {
  font-size: 0.8125rem;
  color: var(--text-muted);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.contact-info-val {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-top: 2px;
}

.contact-info-val a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.contact-info-val a:hover {
  color: var(--primary);
}

.contact-form-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-2xl);
  box-shadow: var(--shadow-sm);
}

.form-group {
  margin-bottom: var(--space-md);
  position: relative;
}

.form-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: var(--space-2xs);
  color: var(--text-primary);
}

.form-label .char-counter {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 400;
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-control:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.form-control.error {
  border-color: var(--error);
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.15);
}

.field-error {
  display: none;
  font-size: 0.8125rem;
  color: var(--error);
  margin-top: 4px;
}

.contact-status-msg {
  display: none;
  padding: var(--space-md);
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  margin-bottom: var(--space-md);
  line-height: 1.5;
}

.contact-status-msg.success {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  background: rgba(16, 185, 129, 0.12);
  color: var(--secondary);
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.contact-status-msg.error {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  background: rgba(239, 68, 68, 0.12);
  color: var(--error);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

/* --------------------------------------------------------------------------
   13. Comprehensive Footer Component
   -------------------------------------------------------------------------- */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: var(--space-3xl) 0 var(--space-xl);
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-lg);
  padding-bottom: var(--space-2xl);
  border-bottom: 1px solid var(--border);
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-2xs);
}

.footer-brand .nav-brand {
  margin-bottom: 4px;
}

.footer-tagline {
  font-size: 0.875rem;
  color: var(--text-secondary);
  max-width: 320px;
  line-height: 1.5;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.footer-nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-fast);
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-md);
  padding-top: var(--space-xl);
}

.footer-socials {
  display: flex;
  gap: var(--space-sm);
}

.footer-social-link {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--surface);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  transition: all var(--transition-fast);
}

.footer-social-link:hover {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm), var(--shadow-primary-glow);
}

.back-to-top-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-full);
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-fast);
}

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