/* ============================================
   Portfolio — Backend Systems & Memory-Centric AI
   Dark theme, glassmorphism, modern typography
   ============================================ */

:root {
  /* 8px grid */
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-5: 40px;
  --space-6: 48px;
  --space-8: 64px;
  --space-10: 80px;
  --space-12: 96px;
  --bg-deep: #0b0f14;
  --bg-card: rgba(15, 23, 32, 0.6);
  --bg-card-hover: rgba(20, 30, 45, 0.8);
  --accent: #4f9cff;
  --accent-dim: rgba(79, 156, 255, 0.15);
  --accent-glow: rgba(79, 156, 255, 0.4);
  --purple: #8b5cf6;
  --purple-dim: rgba(139, 92, 246, 0.15);
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --border: rgba(148, 163, 184, 0.12);
  --gradient-1: linear-gradient(135deg, #4f9cff 0%, #8b5cf6 100%);
  --gradient-bg: radial-gradient(ellipse 80% 50% at 50% -20%, rgba(79, 156, 255, 0.15), transparent),
                 radial-gradient(ellipse 60% 40% at 80% 50%, rgba(139, 92, 246, 0.08), transparent);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --radius: 12px;
  --radius-lg: 20px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-glow: 0 0 40px var(--accent-dim);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-deep);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
  background-image: var(--gradient-bg);
}

/* ----- Particles ----- */
#particles {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
}

/* ----- Navigation ----- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) var(--space-4);
  background: rgba(11, 15, 20, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}

.nav-logo {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  font-size: 1rem;
}

.nav-links {
  display: flex;
  gap: var(--space-4);
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
}

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

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
  transition: var(--transition);
}

@media (max-width: 768px) {
  .nav {
    padding: var(--space-2) var(--space-3);
  }
  .nav-links {
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: var(--space-1);
    padding: var(--space-3);
    background: rgba(11, 15, 20, 0.98);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: transform 0.35s cubic-bezier(0.22, 1, 0.36, 1), opacity 0.35s ease, visibility 0.35s;
  }
  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  .nav-links a {
    display: block;
    padding: var(--space-2) 0;
    border-bottom: 1px solid var(--border);
  }
  .nav-links a:last-child {
    border-bottom: none;
  }
  .nav-toggle {
    display: flex;
  }
  .hero {
    padding: var(--space-8) var(--space-3) var(--space-6);
    min-height: 100vh;
  }
  .hero-avatar-wrap {
    width: 104px;
    height: 104px;
    margin-bottom: var(--space-3);
  }
  .hero-avatar {
    width: 104px;
    height: 104px;
  }
  .hero-avatar-glow {
    inset: -12px;
  }
  .hero-title {
    margin-bottom: var(--space-2);
  }
  .hero-intro {
    margin-bottom: var(--space-3);
  }
  .hero-typing {
    margin-bottom: var(--space-4);
  }
  .section {
    padding: var(--space-8) 0;
  }
  .container {
    padding: 0 var(--space-3);
  }
  .section-subtitle {
    margin-bottom: var(--space-4);
  }
  .projects-grid {
    grid-template-columns: 1fr;
    gap: var(--space-3);
  }
  .project-card {
    padding: var(--space-3);
    gap: var(--space-2);
  }
  .project-icon {
    width: 36px;
    height: 36px;
    top: var(--space-2);
    right: var(--space-2);
  }
  .project-icon svg {
    width: 18px;
    height: 18px;
  }
  .opensource-grid {
    gap: var(--space-2);
  }
  .repo-card {
    padding: var(--space-3);
    gap: var(--space-2);
  }
  .skills-grid {
    gap: var(--space-2);
  }
  .skill-group {
    padding: var(--space-3);
  }
  .skill-group h3 {
    margin-bottom: var(--space-2);
  }
  .tech-logos {
    gap: var(--space-2);
  }
  .tech-logo {
    min-width: 80px;
    padding: var(--space-2) var(--space-3);
  }
  .arch-diagram {
    padding: var(--space-3) var(--space-3);
  }
  .arch-node {
    padding: var(--space-2) var(--space-3);
  }
  .arch-label {
    font-size: 0.9rem;
  }
  .metrics-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-2);
  }
  .metric-card {
    padding: var(--space-3) var(--space-2);
    gap: var(--space-1);
  }
  .metric-value {
    font-size: 1.35rem;
  }
  .metric-label {
    font-size: 0.8rem;
  }
  .about-card {
    padding: var(--space-4);
  }
  .contact-card {
    padding: var(--space-4);
    margin-bottom: var(--space-3);
  }
  .footer {
    padding: var(--space-4) var(--space-3);
  }
  .footer-divider {
    margin-bottom: var(--space-3);
  }
}

/* ----- Container ----- */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

/* ----- Section ----- */
.section {
  position: relative;
  z-index: 1;
  padding: var(--space-12) 0;
}

.section-title {
  font-size: clamp(2rem, 4.5vw, 2.5rem);
  font-weight: 700;
  margin-bottom: var(--space-1);
  margin-top: 0;
  letter-spacing: -0.02em;
  line-height: 1.2;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-subtitle {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.5;
  margin-top: var(--space-1);
  margin-bottom: var(--space-6);
}

/* ----- Section dividers ----- */
.section-divider {
  height: 1px;
  max-width: 200px;
  margin: var(--space-2) auto;
  background: linear-gradient(90deg, transparent, var(--accent-glow), transparent);
  opacity: 0.5;
  position: relative;
  z-index: 1;
}

/* ----- Reveal (scroll animation) ----- */
.reveal {
  opacity: 0;
  transform: translateY(28px) scale(0.98);
  transition: opacity 0.65s cubic-bezier(0.22, 1, 0.36, 1), transform 0.65s cubic-bezier(0.22, 1, 0.36, 1);
}

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

/* ----- Hero ----- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-12) var(--space-4) var(--space-8);
  position: relative;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 100% 80% at 50% 20%, rgba(79, 156, 255, 0.08), transparent 50%),
              radial-gradient(ellipse 60% 60% at 80% 80%, rgba(139, 92, 246, 0.06), transparent 50%);
  pointer-events: none;
}

/* Floating gradient blobs */
.hero-blobs {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

.hero-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.4;
  animation: blobFloat 20s ease-in-out infinite;
}

.hero-blob-1 {
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(79, 156, 255, 0.25) 0%, transparent 70%);
  top: -10%;
  left: -5%;
  animation-delay: 0s;
}

.hero-blob-2 {
  width: 350px;
  height: 350px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.2) 0%, transparent 70%);
  bottom: -5%;
  right: -5%;
  animation-delay: -7s;
}

.hero-blob-3 {
  width: 280px;
  height: 280px;
  background: radial-gradient(circle, rgba(79, 156, 255, 0.15) 0%, transparent 70%);
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  animation-delay: -14s;
}

@keyframes blobFloat {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(30px, -30px) scale(1.05); }
  66% { transform: translate(-20px, 20px) scale(0.95); }
}

.hero-blob-2 { animation-duration: 22s; }
.hero-blob-3 { animation-duration: 25s; }

/* Mouse-follow spotlight */
.hero-spotlight {
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(79, 156, 255, 0.07) 0%, transparent 60%);
  pointer-events: none;
  transform: translate(-50%, -50%);
  left: 50%;
  top: 50%;
  will-change: left, top;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 680px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.hero-avatar-wrap {
  position: relative;
  width: 136px;
  height: 136px;
  margin: 0 auto var(--space-4);
  flex-shrink: 0;
}

.hero-avatar-glow {
  position: absolute;
  inset: -16px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 72%);
  opacity: 0.28;
  animation: avatarGlow 4s ease-in-out infinite;
}

@keyframes avatarGlow {
  0%, 100% { opacity: 0.22; transform: scale(1); }
  50% { opacity: 0.38; transform: scale(1.03); }
}

.hero-avatar {
  position: relative;
  width: 136px;
  height: 136px;
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid var(--accent-dim);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.25), 0 0 20px rgba(79, 156, 255, 0.08);
  transition: var(--transition);
}

.hero-avatar-wrap:hover .hero-avatar {
  border-color: rgba(79, 156, 255, 0.4);
  box-shadow: 0 6px 32px rgba(0, 0, 0, 0.3), 0 0 28px rgba(79, 156, 255, 0.15);
  transform: scale(1.02);
}

.hero-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  display: block;
}

.hero-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.25;
  margin: 0 0 var(--space-3);
  color: var(--text);
}

.gradient-text {
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-intro {
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.55;
  margin: 0 0 var(--space-4);
  max-width: 540px;
}

.hero-typing {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text-muted);
  margin: 0 0 var(--space-5);
  min-height: 1.5em;
}

.typing-prefix {
  color: var(--text-muted);
}

.typing-text {
  color: var(--accent);
}

.typing-cursor {
  color: var(--accent);
  animation: blink 1s step-end infinite;
}

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

.hero-cta {
  display: flex;
  gap: var(--space-2);
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: var(--radius);
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--gradient-1);
  color: white;
  box-shadow: 0 4px 20px rgba(79, 156, 255, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 28px rgba(79, 156, 255, 0.4);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text);
  border: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-dim);
}

.hero-scroll {
  position: absolute;
  bottom: var(--space-4);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  color: var(--text-muted);
  font-size: 0.75rem;
  font-family: var(--font-mono);
}

.scroll-line {
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, var(--accent), transparent);
  border-radius: 2px;
  animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
  0%, 100% { opacity: 0.3; transform: scaleY(0.5); }
  50% { opacity: 1; transform: scaleY(1); }
}

/* ----- Glass card ----- */
.glass {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: var(--transition);
}

.glass:hover {
  background: var(--bg-card-hover);
  border-color: rgba(79, 156, 255, 0.2);
  box-shadow: 0 0 40px var(--accent-dim);
}

/* ----- Overview App (About + Architecture + Metrics) ----- */
.overview-app .section-subtitle {
  margin-bottom: var(--space-5);
}

.app-card {
  max-width: 960px;
  margin: 0 auto;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: 0 24px 48px rgba(0, 0, 0, 0.25);
}

.app-tabs {
  display: flex;
  background: rgba(0, 0, 0, 0.4);
  border-bottom: 1px solid var(--border);
  padding: var(--space-2);
  gap: var(--space-1);
}

.app-tab {
  flex: 1;
  padding: var(--space-2) var(--space-4);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-muted);
  background: transparent;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: color 0.2s ease, background 0.2s ease;
}

.app-tab:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.06);
}

.app-tab.active {
  color: var(--text);
  background: rgba(79, 156, 255, 0.15);
  box-shadow: 0 0 0 1px rgba(79, 156, 255, 0.2);
}

.app-panels {
  position: relative;
  min-height: 360px;
}

.app-panel {
  display: none;
  animation: appPanelIn 0.35s ease;
}

.app-panel.active {
  display: block;
}

.app-panel[hidden] {
  display: none !important;
}

@keyframes appPanelIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.app-panel-inner {
  padding: var(--space-6);
}

.arch-intro {
  font-size: 1rem;
  line-height: 1.55;
  color: var(--text);
  margin: 0 auto var(--space-2);
  text-align: center;
  max-width: 520px;
}

.app-panel-caption {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 0 0 var(--space-4);
  text-align: center;
}

/* About panel — full-width text first, then icons (no cramped column) */
.about-panel {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
  max-width: 800px;
  margin: 0 auto;
}

.about-panel .about-content {
  min-width: 0;
}

.about-panel .about-content p {
  margin: 0 0 var(--space-4);
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.65;
  max-width: 65ch;
}

.about-panel .about-content p:last-child {
  margin-bottom: 0;
}

.about-panel .about-content strong {
  color: var(--accent);
  font-weight: 600;
}

.about-panel .about-icons {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-3);
}

.about-panel .about-icon-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border);
  border-radius: 12px;
  font-size: 0.95rem;
  color: var(--text-muted);
  transition: var(--transition);
}

.about-panel .about-icon-item:hover {
  border-color: rgba(79, 156, 255, 0.25);
  background: rgba(79, 156, 255, 0.06);
}

.about-panel .about-icon {
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-dim);
  border-radius: 10px;
  color: var(--accent);
}

.about-panel .about-icon svg {
  width: 22px;
  height: 22px;
}

/* Architecture panel — live animation */
.arch-panel {
  display: block;
}

.arch-live {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-5);
  align-items: start;
}

@media (max-width: 768px) {
  .arch-live {
    grid-template-columns: 1fr;
  }
}

.arch-flow-column {
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* Single node: appear / disappear (no scroll) */
.arch-node-slot {
  width: 100%;
  max-width: 300px;
  min-height: 72px;
}

.arch-node-current {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  text-align: center;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: opacity 0.25s ease, border 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
}

.arch-node-current.arch-node-fade {
  opacity: 0;
}

.arch-node-current .arch-label {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  display: block;
}

.arch-node-current .arch-sublabel {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: block;
  margin-top: var(--space-1);
}

.arch-node-current.arch-node-entry {
  border-color: rgba(139, 92, 246, 0.4);
  box-shadow: 0 0 20px rgba(139, 92, 246, 0.15);
  background: rgba(139, 92, 246, 0.06);
}

.arch-node-current.arch-node-exit {
  border-color: rgba(34, 197, 94, 0.4);
  box-shadow: 0 0 20px rgba(34, 197, 94, 0.15);
  background: rgba(34, 197, 94, 0.06);
}

.arch-node-current:not(.arch-node-entry):not(.arch-node-exit) {
  border-color: rgba(79, 156, 255, 0.35);
  box-shadow: 0 0 24px rgba(79, 156, 255, 0.12);
  background: rgba(79, 156, 255, 0.06);
}

.arch-step-indicator {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: var(--space-3);
  text-align: center;
}

.arch-example-column {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  min-width: 0;
}

.arch-example-box {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  padding: 0;
  transition: border 0.3s ease;
}

.arch-example-box:hover {
  border-color: rgba(79, 156, 255, 0.2);
}

.arch-example-header {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent);
  margin: 0;
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.15);
}

.arch-example-body {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
  max-height: 340px;
  overflow-y: auto;
  padding: var(--space-4);
}

.arch-example-body::-webkit-scrollbar {
  width: 6px;
}

.arch-example-body::-webkit-scrollbar-track {
  background: rgba(0, 0, 0, 0.15);
  border-radius: 3px;
}

.arch-example-body::-webkit-scrollbar-thumb {
  background: var(--accent-dim);
  border-radius: 3px;
}

.arch-example-body p {
  margin: 0 0 var(--space-3);
  color: var(--text-muted);
}

.arch-example-body p:last-of-type {
  margin-bottom: 0;
}

.arch-example-body p + .arch-example-code {
  margin-top: var(--space-3);
}

.arch-example-body strong {
  color: var(--text);
  font-weight: 600;
}

.arch-example-body code {
  font-family: var(--font-mono);
  font-size: 0.82em;
  color: var(--accent);
  background: rgba(79, 156, 255, 0.1);
  padding: 2px 6px;
  border-radius: 4px;
  word-break: break-word;
}

.arch-example-code {
  display: block;
  margin: var(--space-2) 0 0;
  padding: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.5;
  background: rgba(0, 0, 0, 0.4);
  border-radius: 8px;
  color: var(--text);
  white-space: pre-wrap;
  word-break: break-word;
  border: 1px solid var(--border);
}

.arch-output-box {
  background: rgba(34, 197, 94, 0.06);
  border: 1px solid rgba(34, 197, 94, 0.25);
  border-radius: 12px;
  padding: var(--space-4);
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: opacity 0.4s ease, max-height 0.4s ease, padding 0.4s ease, margin 0.4s ease;
}

.arch-output-box.visible {
  opacity: 1;
  max-height: 280px;
}

.arch-output-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: rgba(34, 197, 94, 0.9);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-2);
}

.arch-output-content {
  font-size: 0.95rem;
  color: var(--text);
  line-height: 1.5;
}

/* Metrics panel inside app */
.metrics-panel {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.app-metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-4);
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
}

.app-metric {
  padding: var(--space-4) var(--space-3);
  text-align: center;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border);
  border-radius: 12px;
  transition: var(--transition);
}

.app-metric:hover {
  border-color: rgba(79, 156, 255, 0.3);
  box-shadow: 0 0 24px var(--accent-dim);
}

.app-metric-value {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}

.app-metric-label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.35;
}

@media (max-width: 768px) {
  .app-tabs {
    padding: var(--space-2);
  }
  .app-tab {
    padding: var(--space-2) var(--space-3);
    font-size: 0.9rem;
  }
  .app-panel-inner {
    padding: var(--space-4);
  }
  .app-panels {
    min-height: 320px;
  }
  .about-panel .about-content p {
    font-size: 1rem;
    max-width: none;
  }
  .about-panel .about-icons {
    grid-template-columns: 1fr 1fr;
  }
}

/* ----- About ----- */
.about-card {
  padding: var(--space-5);
  max-width: 900px;
  margin: 0 auto;
}

.about-grid {
  display: grid;
  gap: var(--space-4);
}

@media (min-width: 768px) {
  .about-grid {
    grid-template-columns: 1fr auto;
  }
}

.about-content p {
  margin: 0 0 var(--space-3);
  color: var(--text-muted);
  line-height: 1.55;
}

.about-content p:last-child {
  margin-bottom: 0;
}

.about-content strong {
  color: var(--accent);
  font-weight: 600;
}

.about-icons {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-2);
  align-content: start;
}

.about-icon-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  background: rgba(0, 0, 0, 0.2);
  border-radius: var(--radius);
  font-size: 0.9rem;
  color: var(--text-muted);
}

.about-icon {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-dim);
  border-radius: 8px;
  color: var(--accent);
}

.about-icon svg {
  width: 20px;
  height: 20px;
}

/* ----- System Architecture ----- */
.architecture .section-subtitle {
  margin-bottom: var(--space-5);
}

.arch-diagram {
  max-width: 420px;
  margin: 0 auto;
  padding: var(--space-5) var(--space-5);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
}

.arch-node {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  text-align: center;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: var(--transition);
}

.arch-node:hover {
  border-color: rgba(79, 156, 255, 0.35);
  box-shadow: 0 0 24px var(--accent-dim);
}

.arch-node-entry {
  border-color: rgba(139, 92, 246, 0.3);
  color: var(--text);
}

.arch-node-exit {
  border-color: rgba(34, 197, 94, 0.35);
  color: var(--text);
}

.arch-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
}

.arch-sublabel {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: var(--space-1);
}

.arch-connector {
  width: 2px;
  height: 28px;
  background: linear-gradient(to bottom, var(--accent), transparent);
  opacity: 0.6;
  flex-shrink: 0;
  position: relative;
}

.arch-connector::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: -5px;
  transform: translateX(-50%);
  border: 5px solid transparent;
  border-top: 5px solid var(--accent);
  border-bottom: none;
  opacity: 0.8;
}

/* ----- System Metrics ----- */
.metrics .section-subtitle {
  margin-bottom: var(--space-5);
}

.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-3);
  max-width: 900px;
  margin: 0 auto;
}

.metric-card {
  padding: var(--space-4) var(--space-3);
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.metric-card:hover {
  border-color: rgba(79, 156, 255, 0.28);
  box-shadow: 0 8px 32px var(--accent-dim);
  transform: translateY(-4px);
}

.metric-value {
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.metric-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ----- Projects ----- */
.projects-grid {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.project-card {
  position: relative;
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  overflow: hidden;
}

.project-card-border {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  padding: 1px;
  background: linear-gradient(135deg, rgba(79, 156, 255, 0.4), rgba(139, 92, 246, 0.2), rgba(79, 156, 255, 0.2));
  background-size: 200% 200%;
  animation: borderGlow 6s ease infinite;
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition);
}

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

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

.project-card-lift {
  transition: transform 0.4s cubic-bezier(0.22, 1, 0.36, 1), box-shadow 0.4s ease, background var(--transition), border-color var(--transition);
}

.project-card-lift:hover {
  transform: translateY(-6px);
  box-shadow: 0 12px 48px rgba(79, 156, 255, 0.18), 0 0 0 1px rgba(79, 156, 255, 0.1);
}

.project-icon {
  position: absolute;
  top: var(--space-3);
  right: var(--space-3);
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  opacity: 0.7;
  transition: opacity var(--transition), transform var(--transition);
}

.project-icon svg {
  width: 22px;
  height: 22px;
}

.project-icon-ai { color: var(--purple); background: var(--purple-dim); }
.project-icon-db { color: var(--accent); background: var(--accent-dim); }
.project-icon-bot { color: #22c55e; background: rgba(34, 197, 94, 0.15); }

.project-card:hover .project-icon {
  opacity: 1;
  transform: scale(1.05);
}

.project-header {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2);
  padding-right: 48px;
}

.project-badge {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  padding: 0.25rem 0.5rem;
  background: var(--purple-dim);
  color: var(--purple);
  border-radius: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.project-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  line-height: 1.3;
  margin: 0;
}

.project-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.52;
  margin: 0;
}

.project-features {
  list-style: none;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin: 0;
  padding: 0;
  line-height: 1.5;
}

.project-features li {
  padding: var(--space-1) 0;
  padding-left: var(--space-4);
  position: relative;
}

.project-features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 4px;
  height: 4px;
  background: var(--accent);
  border-radius: 50%;
}

.project-expand-btn {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-1) 0;
  text-align: left;
  transition: color var(--transition);
  margin: 0;
}

.project-expand-btn:hover {
  color: var(--purple);
}

.project-expand-btn[aria-expanded="true"]::before {
  content: '− ';
}

.project-expand-btn[aria-expanded="false"]::before {
  content: '+ ';
}

.project-expand-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
}

.project-expand-content p {
  font-size: 0.85rem;
  color: var(--text-muted);
  padding-top: var(--space-2);
  margin: 0;
  line-height: 1.5;
}

.project-stack {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin-top: auto;
  padding-top: var(--space-1);
}

.project-stack span {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: var(--space-1) var(--space-2);
  background: rgba(0, 0, 0, 0.3);
  border-radius: 6px;
  color: var(--text-muted);
}

/* ----- Open Source ----- */
.opensource-grid {
  display: grid;
  gap: var(--space-3);
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.repo-card {
  padding: var(--space-4);
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  transition: var(--transition);
}

.repo-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px var(--accent-dim);
}

.repo-card h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  margin: 0 0 var(--space-1);
  line-height: 1.3;
}

.repo-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  flex-grow: 1;
  margin: 0;
  line-height: 1.5;
}

.repo-tags {
  display: flex;
  gap: var(--space-1);
  flex-wrap: wrap;
}

.repo-tags span {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  padding: 0.2rem 0.5rem;
  background: var(--accent-dim);
  color: var(--accent);
  border-radius: 4px;
}

.repo-link {
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 500;
  margin-top: 0.25rem;
}

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

/* ----- Skills ----- */
.skills-grid {
  display: grid;
  gap: var(--space-3);
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.skill-group {
  padding: var(--space-4);
}

.skill-group h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--border);
  color: var(--text);
  line-height: 1.3;
}

.skill-group ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.skill-group li {
  font-size: 0.9rem;
  color: var(--text-muted);
  padding: var(--space-1) 0;
  padding-left: var(--space-4);
  position: relative;
  line-height: 1.45;
}

.skill-group li::before {
  content: '▹';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-family: var(--font-mono);
}

/* ----- Infrastructure / Tech logos ----- */
.tech-logos {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  justify-content: center;
}

.tech-logo {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  transition: var(--transition);
  min-width: 90px;
}

.tech-logo:hover {
  border-color: rgba(79, 156, 255, 0.35);
  color: var(--accent);
  box-shadow: 0 0 24px var(--accent-dim);
  transform: translateY(-2px);
}

.tech-logo-icon {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  transition: var(--transition);
}

.tech-logo:hover .tech-logo-icon {
  filter: drop-shadow(0 0 8px var(--accent-glow));
}

.tech-logo-icon svg {
  width: 100%;
  height: 100%;
}

.tech-logo span {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 500;
}

/* ----- Contact ----- */
.contact-card {
  max-width: 520px;
  margin: 0 auto var(--space-4);
  padding: var(--space-5);
  text-align: center;
}

.contact-card p {
  color: var(--text-muted);
  margin: 0 0 var(--space-4);
  line-height: 1.55;
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  justify-content: center;
}

.contact-license {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  opacity: 0.8;
  margin: 0;
  line-height: 1.5;
}

/* ----- Footer ----- */
.footer {
  position: relative;
  z-index: 1;
  padding: var(--space-6) var(--space-4);
  text-align: center;
}

.footer-divider {
  height: 1px;
  max-width: 120px;
  margin: 0 auto var(--space-4);
  background: linear-gradient(90deg, transparent, var(--accent-glow), transparent);
  opacity: 0.6;
}

.footer-github {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  margin-bottom: var(--space-3);
  color: var(--text-muted);
  transition: var(--transition);
  border-radius: 50%;
}

.footer-github:hover {
  color: var(--accent);
  box-shadow: 0 0 24px var(--accent-dim);
  transform: scale(1.08);
}

.footer-github svg {
  width: 22px;
  height: 22px;
}

.footer-tagline {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  margin: 0 0 var(--space-1);
  line-height: 1.3;
}

.footer-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
  opacity: 0.9;
  margin: 0;
  line-height: 1.4;
}