/* ==========================================================================
   CSS Variables & Theme Setup
   ========================================================================== */
:root {
  --bg-color: #0f172a; /* Slate 900 */
  --bg-color-lighter: #1e293b; /* Slate 800 */
  --card-bg: rgba(30, 41, 59, 0.7);
  --card-border: rgba(255, 255, 255, 0.1);
  --text-main: #f8fafc; /* Slate 50 */
  --text-muted: #94a3b8; /* Slate 400 */
  --accent-color: #38bdf8; /* Sky 400 */
  --accent-color-hover: #0ea5e9; /* Sky 500 */
  --gradient-text: linear-gradient(135deg, #38bdf8 0%, #818cf8 100%);
  --gradient-bg: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
  
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-heading: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
  --shadow-glow: 0 0 20px rgba(56, 189, 248, 0.15);
  
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --max-width: 1200px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px; /* Account for sticky header */
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  background-image: radial-gradient(circle at top right, rgba(30, 27, 75, 0.5) 0%, transparent 40%),
                    radial-gradient(circle at bottom left, rgba(15, 23, 42, 0.8) 0%, transparent 40%);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  font-weight: 700;
  color: var(--text-main);
}

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

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

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

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

/* ==========================================================================
   Typography & Utilities
   ========================================================================== */
.highlight {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: inline-block;
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.section-header p {
  color: var(--text-muted);
  font-size: 1.125rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-full);
  font-weight: 500;
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--transition-normal);
  border: none;
  outline: none;
}

.btn-primary {
  background: var(--text-main);
  color: var(--bg-color);
}

.btn-primary:hover {
  background: var(--accent-color);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(56, 189, 248, 0.3);
}

.btn-accent {
  background: var(--gradient-text);
  color: var(--bg-color);
  border: none;
  font-weight: 700;
  box-shadow: 0 0 15px rgba(56, 189, 248, 0.3);
}

.btn-accent:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 0 25px rgba(56, 189, 248, 0.5);
  color: var(--bg-color);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-main);
  backdrop-filter: blur(10px);
  border: 1px solid var(--card-border);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateY(-2px);
}

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

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--text-muted);
}

/* ==========================================================================
   Navigation
   ========================================================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  transition: all var(--transition-normal);
}

.nav-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 80px;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-main);
  letter-spacing: -0.5px;
}

.logo .dot {
  color: var(--accent-color);
}

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

.nav-links a {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
}

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

.nav-links a::after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: -4px;
  left: 0;
  background-color: var(--accent-color);
  transition: width var(--transition-fast);
}

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

.mobile-nav-toggle {
  display: none;
  background: transparent;
  color: var(--text-main);
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  padding-top: 80px; /* Offset nav */
}

.hero-content {
  position: relative;
  z-index: 10;
}

.hero-text {
  max-width: 800px;
}

.greeting {
  font-size: 1.2rem;
  font-family: var(--font-heading);
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.hero-title {
  font-size: clamp(3rem, 8vw, 5.5rem);
  letter-spacing: -1.5px;
  margin-bottom: 1.5rem;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-description {
  font-size: clamp(1.1rem, 2vw, 1.25rem);
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  max-width: 650px;
}

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

/* Background Glow Effects */
.glow-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  z-index: 1;
  opacity: 0.4;
}

.orb-1 {
  top: 20%;
  left: 10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.4) 0%, transparent 70%);
}

.orb-2 {
  bottom: 10%;
  right: 5%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(129, 140, 248, 0.3) 0%, transparent 70%);
}

/* ==========================================================================
   Portfolio Section
   ========================================================================== */
.portfolio {
  padding: 8rem 2rem;
}

.filters {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 3rem;
}

.filter-btn {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--card-border);
  color: var(--text-muted);
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-full);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-main);
}

.filter-btn.active {
  background: var(--text-main);
  color: var(--bg-color);
  border-color: var(--text-main);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 2rem;
}

.loading-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: 4rem;
  color: var(--text-muted);
  font-style: italic;
}

/* Project Card */
.project-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
  backdrop-filter: blur(10px);
  position: relative;
}

.project-card:hover {
  transform: translateY(-8px);
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: var(--shadow-md), var(--shadow-glow);
}



.featured-badge {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(4px);
  border: 1px solid var(--accent-color);
  color: var(--accent-color);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

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

.card-category {
  color: var(--accent-color);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.card-title {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
}

.card-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.tech-tag {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
  font-size: 0.75rem;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.card-links {
  display: flex;
  gap: 1rem;
  margin-top: auto;
  border-top: 1px solid var(--card-border);
  padding-top: 1.25rem;
}

.card-link {
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.9rem;
  font-weight: 500;
}

.card-link:hover {
  color: var(--accent-color);
}

.view-all-container {
  display: flex;
  justify-content: center;
  margin-top: 4rem;
}

/* ==========================================================================
   Library Section
   ========================================================================== */
.library {
  padding: 6rem 2rem 4rem;
  position: relative;
  z-index: 5;
}

.library-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 2rem;
}

.library-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  backdrop-filter: blur(10px);
}

.library-card h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--accent-color);
}

.articles-card {
  display: flex;
  flex-direction: column;
}

.book-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.book-list li a {
  display: flex;
  flex-direction: column;
  padding: 1rem;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-md);
  color: var(--text-main);
  transition: all var(--transition-fast);
  font-weight: 600;
  height: 100%;
}

.book-list li a span {
  font-weight: 400;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
}

.book-list li a:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--accent-color);
  transform: translateY(-2px);
}

/* ==========================================================================
   About Section
   ========================================================================== */
.about {
  padding: 8rem 2rem;
  background: linear-gradient(to bottom, transparent, rgba(30, 41, 59, 0.3));
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.about-content {
  display: flex;
  justify-content: center;
}

.about-text {
  max-width: 800px;
}

.about-text h2 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: inline-block;
}

.about-text p {
  color: var(--text-muted);
  font-size: 1.125rem;
  margin-bottom: 1.5rem;
}

.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2rem;
}

.skill-tag {
  background: rgba(56, 189, 248, 0.1);
  color: var(--accent-color);
  border: 1px solid rgba(56, 189, 248, 0.2);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-full);
  font-weight: 500;
  font-size: 0.9rem;
}

/* ==========================================================================
   Footer
   ========================================================================== */
footer {
  background: #0f172a;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding: 5rem 2rem 2rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 3rem;
  margin-bottom: 4rem;
}

.footer-info {
  max-width: 400px;
}

.footer-info h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.footer-info p {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

.email-link {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-main);
  position: relative;
  display: inline-block;
}

.email-link::after {
  content: '';
  position: absolute;
  width: 100%;
  height: 2px;
  bottom: -4px;
  left: 0;
  background-color: var(--accent-color);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--transition-normal);
}

.email-link:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

.social-links {
  display: flex;
  gap: 1.5rem;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  color: var(--text-main);
  font-size: 1.5rem;
  transition: all var(--transition-normal);
}

.social-links a:hover {
  background: var(--accent-color);
  color: #fff;
  border-color: var(--accent-color);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow);
}

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* ==========================================================================
   Animations & Responsive
   ========================================================================== */
.fade-in-section {
  opacity: 0;
  transform: translateY(20px);
  visibility: hidden;
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
  will-change: opacity, visibility;
}

.fade-in-section.is-visible {
  opacity: 1;
  transform: none;
  visibility: visible;
}

@media (max-width: 768px) {
  .nav-links {
    display: none; /* simple mobile nav hidden by default */
  }
  
  .mobile-nav-toggle {
    display: block;
  }
  
  .nav-links.active {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 80px;
    left: 0;
    width: 100%;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    box-shadow: var(--shadow-md);
  }
  

  .hero-title {
    font-size: clamp(2.5rem, 10vw, 3.5rem);
  }
  
  .projects-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-content {
    flex-direction: column;
  }
  
  .library-grid {
    grid-template-columns: 1fr;
  }
}