/* ===========================================
   DESIGN SYSTEM - Personal Branding Portfolio
     Fullstack Developer | NodeJS & ReactJS
   =========================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --bg-card: rgba(255, 255, 255, 0.03);
  --bg-card-hover: rgba(255, 255, 255, 0.06);
  --text-primary: #ffffff;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --accent-cyan: #06b6d4;
  --accent-purple: #a855f7;
  --accent-blue: #3b82f6;
  --accent-green: #10b981;
  --gradient-primary: linear-gradient(135deg, var(--accent-cyan), var(--accent-purple));
  --gradient-hero: linear-gradient(135deg, #0a0a0f 0%, #1a1a2e 50%, #0a0a0f 100%);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(6, 182, 212, 0.3);
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-4xl: 6rem;
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);
  --container-max: 1200px;
  --container-padding: 1.5rem;
}

*, *::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(--bg-primary); color: var(--text-primary); line-height: 1.6; overflow-x: hidden; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
img { max-width: 100%; height: auto; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
.container { width: 100%; max-width: var(--container-max); margin: 0 auto; padding: 0 var(--container-padding); }
.gradient-text { background: var(--gradient-primary); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.mono { font-family: var(--font-mono); }
section { padding: var(--spacing-4xl) 0; }
.section-header { text-align: center; margin-bottom: var(--spacing-3xl); }
.section-label { display: inline-block; font-family: var(--font-mono); font-size: 0.875rem; color: var(--accent-cyan); text-transform: uppercase; letter-spacing: 0.15em; margin-bottom: var(--spacing-md); }
.section-title { font-size: clamp(2rem, 5vw, 3rem); font-weight: 700; margin-bottom: var(--spacing-md); }
.section-subtitle { font-size: 1.125rem; color: var(--text-secondary); max-width: 600px; margin: 0 auto; }

.navbar { position: fixed; top: 0; left: 0; right: 0; z-index: 1000; padding: var(--spacing-lg) 0; transition: all var(--transition-base); background: transparent; }
.navbar.scrolled { background: rgba(10, 10, 15, 0.9); backdrop-filter: blur(20px); border-bottom: 1px solid var(--border-color); padding: var(--spacing-md) 0; }
.navbar .container { display: flex; justify-content: space-between; align-items: center; }
.nav-logo { font-size: 1.5rem; font-weight: 700; letter-spacing: -0.02em; }
.nav-links { display: flex; align-items: center; gap: var(--spacing-xl); }
.nav-link { font-size: 0.9rem; font-weight: 500; color: var(--text-secondary); transition: color var(--transition-fast); position: relative; }
.nav-link::after { content: ''; position: absolute; bottom: -4px; left: 0; width: 0; height: 2px; background: var(--gradient-primary); transition: width var(--transition-base); }
.nav-link:hover { color: var(--text-primary); }
.nav-link:hover::after { width: 100%; }
.nav-toggle { display: none; flex-direction: column; gap: 5px; padding: var(--spacing-sm); }
.nav-toggle span { display: block; width: 24px; height: 2px; background: var(--text-primary); transition: all var(--transition-fast); }

.lang-switcher { display: inline-flex; align-items: center; gap: 0.25rem; padding: 0.25rem; border: 1px solid var(--border-color); border-radius: 999px; background: rgba(255,255,255,0.04); box-shadow: inset 0 1px 0 rgba(255,255,255,0.04); }
.lang-btn { display: inline-flex; align-items: center; justify-content: center; gap: 0.35rem; min-width: 56px; min-height: 34px; padding: 0.35rem 0.65rem; border-radius: 999px; color: var(--text-secondary); font-size: 0.8rem; font-weight: 700; letter-spacing: 0.02em; transition: all var(--transition-base); }
.lang-btn:hover { color: var(--text-primary); background: rgba(255,255,255,0.06); transform: translateY(-1px); }
.lang-btn.active { color: #0a0a0f; background: var(--gradient-primary); box-shadow: 0 8px 24px rgba(6, 182, 212, 0.22); }
.light-mode .lang-switcher { border-color: rgba(124, 58, 237, 0.14); background: rgba(255,255,255,0.7); }
.light-mode .lang-btn { color: #64748b; }
.light-mode .lang-btn:hover { color: #0f172a; background: rgba(124, 58, 237, 0.08); }
.light-mode .lang-btn.active { color: #ffffff; background: linear-gradient(135deg, #8b5cf6, #ec4899); box-shadow: 0 8px 24px rgba(124, 58, 237, 0.2); }

.hero { min-height: 100vh; display: flex; align-items: center; justify-content: center; position: relative; overflow: hidden; padding-top: 80px; }
.hero-bg { position: absolute; inset: 0; background: var(--gradient-hero); z-index: -2; }
.hero-grid { position: absolute; inset: 0; background-image: linear-gradient(rgba(6, 182, 212, 0.03) 1px, transparent 1px), linear-gradient(90deg, rgba(6, 182, 212, 0.03) 1px, transparent 1px); background-size: 60px 60px; z-index: -1; mask-image: radial-gradient(ellipse 80% 50% at 50% 50%, black 40%, transparent 100%); }
.hero-glow { position: absolute; width: 600px; height: 600px; border-radius: 50%; filter: blur(120px); opacity: 0.4; z-index: -1; }
.hero-glow-1 { top: 10%; left: 20%; background: var(--accent-cyan); }
.hero-glow-2 { bottom: 20%; right: 20%; background: var(--accent-purple); }
.hero-content { text-align: center; max-width: 900px; padding: 0 var(--container-padding); }
.hero-badge { display: inline-flex; align-items: center; gap: var(--spacing-sm); padding: var(--spacing-sm) var(--spacing-lg); background: var(--bg-card); border: 1px solid var(--border-color); border-radius: 100px; font-size: 0.875rem; color: var(--text-secondary); margin-bottom: var(--spacing-xl); animation: fadeInUp 0.6s ease forwards; }
.hero-badge .dot { width: 8px; height: 8px; background: var(--accent-green); border-radius: 50%; animation: pulse 2s ease-in-out infinite; }
.hero-title { font-size: clamp(2.5rem, 8vw, 5rem); font-weight: 800; line-height: 1.1; letter-spacing: -0.03em; margin-bottom: var(--spacing-lg); animation: fadeInUp 0.6s ease 0.1s forwards; opacity: 0; }
.hero-title .highlight { position: relative; display: inline-block; }
.hero-subtitle { font-size: clamp(1.125rem, 2.5vw, 1.5rem); color: var(--text-secondary); margin-bottom: var(--spacing-md); animation: fadeInUp 0.6s ease 0.2s forwards; opacity: 0; }
.hero-tech { display: flex; justify-content: center; align-items: center; gap: var(--spacing-md); font-family: var(--font-mono); font-size: 1rem; color: var(--text-muted); margin-bottom: var(--spacing-2xl); animation: fadeInUp 0.6s ease 0.3s forwards; opacity: 0; }
.hero-tech .divider { width: 4px; height: 4px; background: var(--accent-cyan); border-radius: 50%; }
.hero-tech span { transition: color var(--transition-fast); }
.hero-tech span:hover { color: var(--accent-cyan); }
.hero-cta { display: flex; justify-content: center; gap: var(--spacing-lg); flex-wrap: wrap; animation: fadeInUp 0.6s ease 0.4s forwards; opacity: 0; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: var(--spacing-sm); padding: var(--spacing-md) var(--spacing-xl); font-size: 0.95rem; font-weight: 600; border-radius: var(--radius-lg); transition: all var(--transition-base); }
.btn-primary { background: var(--gradient-primary); color: var(--bg-primary); position: relative; overflow: hidden; }
.btn-secondary { background: var(--bg-card); border: 1px solid var(--border-color); color: var(--text-primary); }
.btn-secondary:hover { background: var(--bg-card-hover); border-color: var(--accent-cyan); box-shadow: 0 0 20px rgba(6, 182, 212, 0.2); }
.btn-backend, .btn-frontend { min-width: 220px; }
.btn-backend { background: var(--gradient-primary); color: var(--bg-primary); }
.btn-frontend { background: var(--bg-card); border: 1px solid var(--border-color); color: var(--text-primary); }

.overview { background: var(--bg-primary); }
.overview-grid, .skills-grid, .portfolio-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--spacing-xl); }
.overview-card, .skill-card, .project-card { background: var(--bg-card); border: 1px solid var(--border-color); border-radius: var(--radius-2xl); padding: var(--spacing-2xl); transition: all var(--transition-base); }
.overview-card:hover, .skill-card:hover, .project-card:hover { transform: translateY(-8px); border-color: var(--accent-cyan); box-shadow: 0 20px 40px rgba(0,0,0,0.2); }
.overview-icon, .skill-icon { font-size: 2.5rem; margin-bottom: var(--spacing-md); }
.overview-card h3, .skill-card-title, .project-title { font-size: 1.35rem; margin-bottom: var(--spacing-sm); }
.overview-card p, .skill-card-desc, .project-desc { color: var(--text-secondary); margin-bottom: var(--spacing-md); }
.overview-tags, .skill-tags, .project-stack { display: flex; flex-wrap: wrap; gap: var(--spacing-sm); }
.overview-tags span, .skill-tag, .stack-tag { padding: 0.35rem 0.75rem; border-radius: 999px; background: rgba(255,255,255,0.05); color: var(--text-secondary); font-size: 0.8rem; }
.overview-link, .project-link { display: inline-flex; margin-top: var(--spacing-lg); color: var(--accent-cyan); font-weight: 700; }
.skills, .portfolio, .contact { background: var(--bg-secondary); }
.project-image { height: 150px; border-radius: var(--radius-xl); background: rgba(255,255,255,0.04); display: flex; align-items: center; justify-content: center; margin-bottom: var(--spacing-lg); }
.project-preview { font-size: 4rem; }
.project-category { display: inline-block; margin-bottom: var(--spacing-sm); color: var(--accent-cyan); font-size: 0.8rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; }
.contact-content { text-align: center; max-width: 760px; margin: 0 auto; }
.contact-title { font-size: clamp(2rem, 5vw, 3rem); margin-bottom: var(--spacing-md); }
.contact-desc { color: var(--text-secondary); font-size: 1.125rem; margin-bottom: var(--spacing-xl); }
.contact-email { display: inline-flex; align-items: center; justify-content: center; color: var(--accent-cyan); font-weight: 700; }
.footer { padding: var(--spacing-xl) 0; background: var(--bg-primary); border-top: 1px solid var(--border-color); text-align: center; color: var(--text-muted); }

.fade-in { opacity: 0; transform: translateY(24px); transition: all 0.7s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }
.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }
@keyframes fadeInUp { from { opacity: 0; transform: translateY(24px); } to { opacity: 1; transform: translateY(0); } }
@keyframes pulse { 0%, 100% { opacity: 1; transform: scale(1); } 50% { opacity: .55; transform: scale(1.25); } }

@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .nav-links { position: fixed; top: 72px; left: var(--container-padding); right: var(--container-padding); flex-direction: column; align-items: stretch; gap: var(--spacing-md); padding: var(--spacing-lg); border-radius: var(--radius-xl); background: rgba(10, 10, 15, 0.96); border: 1px solid var(--border-color); transform: translateY(-12px); opacity: 0; pointer-events: none; transition: all var(--transition-base); }
  .nav-links.active { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .nav-links li { width: 100%; }
  .nav-link { display: block; padding: .5rem 0; }
  .lang-switcher { width: 100%; justify-content: center; }
  .lang-btn { flex: 1; }
  .hero-tech { flex-wrap: wrap; }
  .hero-cta { flex-direction: column; align-items: center; }
  .btn { width: 100%; max-width: 280px; }
  .skills-grid, .portfolio-grid, .overview-grid { grid-template-columns: 1fr; }
}
@media (max-width: 375px) { :root { --container-padding: 1rem; } .hero-title { font-size: 2rem; } .section-title { font-size: 1.75rem; } }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }