/* ============================================================
   CV Portfolio – Design System & Styles
   Dark-mode first, mobile-first, single-page portfolio
   ============================================================ */

/* ---------- Google Font ---------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background 0.4s ease, color 0.4s ease;
  overflow-x: hidden;
}

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

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

/* ---------- Custom Properties – Dark (default) ---------- */
:root {
  --bg-primary: #0a0a1a;
  --bg-secondary: #111128;
  --bg-tertiary: #16163a;
  --text-primary: #e8e8f0;
  --text-secondary: #9a9ab8;
  --accent: #4fc3f7;
  --accent-dark: #0288d1;
  --accent-glow: rgba(79, 195, 247, 0.2);
  --accent-glow-strong: rgba(79, 195, 247, 0.35);
  --card-bg: #13132e;
  --card-border: rgba(79, 195, 247, 0.08);
  --border: #1e1e48;
  --shadow: rgba(0, 0, 0, 0.5);
  --glass-bg: rgba(10, 10, 26, 0.75);
  --glass-border: rgba(79, 195, 247, 0.1);
  --gradient-text: linear-gradient(135deg, #4fc3f7, #81d4fa, #b3e5fc);
  --gradient-accent: linear-gradient(135deg, #4fc3f7, #0288d1);
  --section-gap: clamp(60px, 10vw, 100px);
}

/* ---------- Custom Properties – Light ---------- */
[data-theme="light"] {
  --bg-primary: #f0f2f8;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e8eaf0;
  --text-primary: #1a1a2e;
  --text-secondary: #555570;
  --accent: #0288d1;
  --accent-dark: #01579b;
  --accent-glow: rgba(2, 136, 209, 0.12);
  --accent-glow-strong: rgba(2, 136, 209, 0.22);
  --card-bg: #ffffff;
  --card-border: rgba(2, 136, 209, 0.1);
  --border: #d8d8e8;
  --shadow: rgba(0, 0, 0, 0.08);
  --glass-bg: rgba(240, 242, 248, 0.8);
  --glass-border: rgba(2, 136, 209, 0.12);
  --gradient-text: linear-gradient(135deg, #0288d1, #01579b);
  --gradient-accent: linear-gradient(135deg, #0288d1, #01579b);
}

/* ---------- Typography ---------- */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  font-weight: 700;
}

h1 { font-size: clamp(2.2rem, 5vw, 3.8rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.4rem); }
h3 { font-size: clamp(1.1rem, 2vw, 1.4rem); }

p {
  font-size: clamp(0.95rem, 1.5vw, 1.05rem);
}

/* ---------- Layout ---------- */
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: var(--section-gap) 0;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-header h2 {
  display: inline-block;
  position: relative;
  margin-bottom: 12px;
}

.section-header h2::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 50%;
  transform: translateX(-50%);
  width: 50px;
  height: 3px;
  border-radius: 2px;
  background: var(--gradient-accent);
}

.section-header p {
  color: var(--text-secondary);
  margin-top: 16px;
}

/* ---------- Scroll Reveal ---------- */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* stagger children */
.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ============================================================
   NAVBAR
   ============================================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 16px 0;
  background: var(--glass-bg);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--glass-border);
  transition: padding 0.3s ease, background 0.3s ease;
}

.navbar.scrolled {
  padding: 10px 0;
  box-shadow: 0 4px 30px var(--shadow);
}

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

.nav-logo {
  font-size: 1.3rem;
  font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.5px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  transition: color 0.3s ease;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
  transition: width 0.3s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
}

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

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: 2px solid var(--border);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-primary);
  font-size: 1.1rem;
  transition: border-color 0.3s, transform 0.3s, background 0.3s;
}

.theme-toggle:hover {
  border-color: var(--accent);
  transform: rotate(30deg);
  background: var(--accent-glow);
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 6px;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding-top: 80px;
}

.hero::before {
  content: '';
  position: absolute;
  top: -40%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  animation: float 8s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -15%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(79, 195, 247, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  animation: float 10s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(30px, -30px); }
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--accent-glow);
  border: 1px solid var(--card-border);
  border-radius: 100px;
  padding: 6px 16px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--accent);
  margin-bottom: 24px;
}

.hero-badge span {
  display: inline-block;
  width: 8px;
  height: 8px;
  background: var(--accent);
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.hero h1 {
  margin-bottom: 8px;
}

.hero h1 .gradient-text {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-title-sub {
  font-size: clamp(1.1rem, 2.5vw, 1.6rem);
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.hero-description {
  max-width: 560px;
  color: var(--text-secondary);
  margin-bottom: 32px;
  font-size: clamp(0.95rem, 1.5vw, 1.05rem);
}

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

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: 12px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: transform 0.3s, box-shadow 0.3s, background 0.3s;
}

.btn-primary {
  background: var(--gradient-accent);
  color: #fff;
  box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px var(--accent-glow-strong);
}

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

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

/* ============================================================
   ABOUT
   ============================================================ */
.about-content {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  max-width: 800px;
  margin: 0 auto;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.about-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.stat-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 16px;
  padding: 24px;
  text-align: center;
  transition: transform 0.3s, box-shadow 0.3s;
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px var(--shadow);
}

.stat-card .stat-number {
  font-size: 2rem;
  font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-card .stat-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ============================================================
   SKILLS
   ============================================================ */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.skill-category {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  padding: 32px;
  transition: transform 0.3s, box-shadow 0.3s;
}

.skill-category:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px var(--shadow);
}

.skill-category-icon {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  background: var(--accent-glow);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 16px;
}

.skill-category h3 {
  margin-bottom: 16px;
  color: var(--text-primary);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.skill-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 100px;
  font-size: 0.85rem;
  font-weight: 500;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: border-color 0.3s, color 0.3s, background 0.3s;
}

.skill-tag:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-glow);
}

/* ============================================================
   PROJECTS
   ============================================================ */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 28px;
}

.project-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  overflow: hidden;
  transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.project-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 60px var(--shadow);
}

.project-card-image {
  position: relative;
  overflow: hidden;
  height: 200px;
}

.project-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.project-card:hover .project-card-image img {
  transform: scale(1.05);
}

.project-card-image .project-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(0,0,0,0.6), transparent);
  opacity: 0;
  display: flex;
  align-items: flex-end;
  justify-content: flex-end;
  padding: 16px;
  transition: opacity 0.3s;
}

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

.project-overlay a {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  margin-left: 8px;
  transition: transform 0.3s;
}

.project-overlay a:hover {
  transform: scale(1.1);
}

.project-card-body {
  padding: 24px;
}

.project-card-body h3 {
  margin-bottom: 8px;
  color: var(--text-primary);
}

.project-card-body p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 16px;
}

.project-features {
  margin-bottom: 16px;
}

.project-features li {
  color: var(--text-secondary);
  font-size: 0.85rem;
  padding: 4px 0;
  padding-left: 18px;
  position: relative;
}

.project-features li::before {
  content: '▹';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-size: 0.9rem;
}

.project-tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.project-tech-tag {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 100px;
  background: var(--accent-glow);
  color: var(--accent);
  border: 1px solid var(--card-border);
}

/* ============================================================
   EDUCATION
   ============================================================ */
.education-card {
  max-width: 650px;
  margin: 0 auto;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  padding: 40px;
  position: relative;
  overflow: hidden;
}

.education-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--gradient-accent);
  border-radius: 0 2px 2px 0;
}

.education-icon {
  width: 56px;
  height: 56px;
  border-radius: 16px;
  background: var(--accent-glow);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 20px;
}

.education-card h3 {
  font-size: 1.3rem;
  margin-bottom: 8px;
}

.education-card .education-major {
  color: var(--accent);
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 16px;
}

.education-details {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
}

.education-detail {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.education-detail .detail-icon {
  color: var(--accent);
  font-size: 1rem;
}

/* ============================================================
   CONTACT
   ============================================================ */
.contact-content {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
}

.contact-content > p {
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
  margin-bottom: 32px;
}

.contact-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 24px;
  border-radius: 14px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  color: var(--text-primary);
  font-weight: 500;
  font-size: 0.95rem;
  transition: transform 0.3s, border-color 0.3s, box-shadow 0.3s, color 0.3s;
}

.contact-link:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: 0 8px 30px var(--accent-glow);
}

.contact-link .link-icon {
  font-size: 1.2rem;
}

.contact-cta {
  margin-top: 24px;
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  text-align: center;
}

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

.footer .footer-heart {
  color: var(--accent);
}

/* ============================================================
   MOBILE RESPONSIVE
   ============================================================ */
@media (max-width: 768px) {
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    background: var(--bg-secondary);
    flex-direction: column;
    align-items: flex-start;
    padding: 80px 32px 32px;
    gap: 24px;
    transition: right 0.4s ease;
    box-shadow: -10px 0 40px var(--shadow);
    z-index: 999;
  }

  .nav-links.open {
    right: 0;
  }

  .hamburger {
    display: flex;
    z-index: 1001;
  }

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

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

  .nav-open .hamburger span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

  .hero {
    min-height: auto;
    padding-top: 120px;
    padding-bottom: 60px;
  }

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

  .hero-cta .btn {
    width: 100%;
    justify-content: center;
  }

  .about-stats {
    grid-template-columns: 1fr;
    gap: 12px;
  }

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

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

  .education-card {
    padding: 28px 24px;
  }

  .education-details {
    flex-direction: column;
    gap: 12px;
  }

  .contact-links {
    flex-direction: column;
    align-items: stretch;
  }
}

/* Tablet */
@media (min-width: 769px) and (max-width: 1024px) {
  .projects-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Desktop enhancements */
@media (min-width: 1025px) {
  .hero-content {
    max-width: 680px;
  }
}

/* Nav overlay for mobile */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 998;
}

.nav-overlay.show {
  display: block;
}