/* ==========================================================================
   Aravindh Subramaniyan — Personal Portfolio (portfolio.avenra.org)
   Design System: Swiss Editorial / Minimalist Systems Engineering
   ========================================================================== */

/* --------------------------------------------------------------------------
   Root Variables & Color System
   -------------------------------------------------------------------------- */
:root {
  /* Color Palette (Light mode default) */
  --bg: #FAFAF8;
  --surface: #FFFFFF;
  --surface-subtle: #F4F4F0;
  --text-primary: #171717;
  --text-secondary: #666666;
  --text-muted: #8A8A8A;
  --border: #E5E5E5;
  --border-subtle: #EDEDEB;
  --accent: #171717;
  --accent-blue: #1D4ED8;
  --accent-blue-subtle: rgba(29, 78, 216, 0.08);
  --live-indicator: #059669;

  /* Typography */
  --font-sans: 'Geist', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: 'Geist Mono', ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  /* Spacing & Layout */
  --max-width: 900px;
  --container-px: 32px;
  --section-spacing: 56px;
  --section-spacing-mobile: 44px;

  /* Radii & Shadows (Minimalist restraint) */
  --radius-xs: 3px;
  --radius-sm: 5px;
  --radius-pill: 9999px;

  /* Transitions */
  --transition-fast: 140ms ease-out;
}

/* Dark Mode via prefers-color-scheme */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0F0F0E;
    --surface: #151514;
    --surface-subtle: #1C1C1A;
    --text-primary: #ECECE9;
    --text-secondary: #969692;
    --text-muted: #6B6B67;
    --border: #242422;
    --border-subtle: #1C1C1A;
    --accent: #ECECE9;
    --accent-blue: #60A5FA;
    --accent-blue-subtle: rgba(96, 165, 250, 0.12);
    --live-indicator: #10B981;
  }
}

/* Explicit Manual Theme Overrides */
[data-theme="dark"] {
  --bg: #0F0F0E;
  --surface: #151514;
  --surface-subtle: #1C1C1A;
  --text-primary: #ECECE9;
  --text-secondary: #969692;
  --text-muted: #6B6B67;
  --border: #242422;
  --border-subtle: #1C1C1A;
  --accent: #ECECE9;
  --accent-blue: #60A5FA;
  --accent-blue-subtle: rgba(96, 165, 250, 0.12);
  --live-indicator: #10B981;
}

[data-theme="light"] {
  --bg: #FAFAF8;
  --surface: #FFFFFF;
  --surface-subtle: #F4F4F0;
  --text-primary: #171717;
  --text-secondary: #666666;
  --text-muted: #8A8A8A;
  --border: #E5E5E5;
  --border-subtle: #EDEDEB;
  --accent: #171717;
  --accent-blue: #1D4ED8;
  --accent-blue-subtle: rgba(29, 78, 216, 0.08);
  --live-indicator: #059669;
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg);
  color: var(--text-primary);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
  font-size: 16px;
  line-height: 1.6;
}

body {
  background-color: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Selection */
::selection {
  background-color: var(--text-primary);
  color: var(--bg);
}

/* Skip Link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 20px;
  background: var(--text-primary);
  color: var(--bg);
  padding: 8px 16px;
  font-size: 0.875rem;
  font-family: var(--font-mono);
  z-index: 999;
  border-radius: var(--radius-xs);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 16px;
}

/* Focus Visible */
:focus-visible {
  outline: 2px solid var(--text-primary);
  outline-offset: 3px;
}

/* Links */
a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

/* --------------------------------------------------------------------------
   Layout Containers
   -------------------------------------------------------------------------- */
.site-container {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 0 var(--container-px);
}

.site-main {
  flex: 1 0 auto;
}

.section-divider {
  border: 0;
  border-top: 1px solid var(--border);
  margin: var(--section-spacing) 0;
}

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */
.site-header {
  padding-top: 40px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: 12px;
}

.site-brand {
  font-family: var(--font-sans);
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  display: inline-flex;
  align-items: center;
}

.site-brand .dot {
  color: var(--text-muted);
  transition: color var(--transition-fast);
}

.site-brand:hover .dot {
  color: var(--accent-blue);
}

.availability-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  padding: 2px 8px;
  background: var(--surface-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
}

.pulse-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--live-indicator);
  display: inline-block;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav-link {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 450;
  letter-spacing: -0.01em;
  padding: 6px 0;
  display: inline-flex;
  align-items: center;
  gap: 2px;
  position: relative;
}

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

.nav-link.external-link svg {
  opacity: 0.5;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.nav-link.external-link:hover svg {
  opacity: 1;
  transform: translate(1px, -1px);
}

/* Theme Toggle Button */
.theme-toggle-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 4px 8px;
  border-radius: var(--radius-xs);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
  line-height: 1;
}

.theme-toggle-btn:hover {
  background: var(--surface-subtle);
  color: var(--text-primary);
  border-color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Introduction Section
   -------------------------------------------------------------------------- */
.intro-section {
  padding-top: var(--section-spacing);
}

.intro-lead {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.intro-name {
  font-size: 2.125rem;
  font-weight: 600;
  letter-spacing: -0.035em;
  line-height: 1.15;
  color: var(--text-primary);
}

.intro-headline {
  font-size: 1.25rem;
  font-weight: 400;
  letter-spacing: -0.02em;
  line-height: 1.45;
  color: var(--text-primary);
}

.intro-metadata {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  letter-spacing: -0.01em;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.intro-metadata .sep {
  color: var(--border);
}

.intro-summary {
  margin-top: 24px;
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 760px;
}

.intro-summary strong {
  color: var(--text-primary);
  font-weight: 500;
}

.intro-actions {
  margin-top: 28px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.action-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  padding: 8px 16px;
  border-radius: var(--radius-xs);
  transition: all var(--transition-fast);
  cursor: pointer;
  line-height: 1.2;
}

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

.action-btn-primary:hover {
  background: #333333;
  color: #FFFFFF;
}

[data-theme="dark"] .action-btn-primary:hover,
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .action-btn-primary:hover {
    background: #FFFFFF;
    color: #000000;
  }
}

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

.action-btn-secondary:hover {
  background: var(--surface-subtle);
  border-color: var(--text-muted);
}

.action-btn .meta-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  opacity: 0.75;
}

.copy-feedback-toast {
  display: none;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--live-indicator);
  margin-left: 4px;
}

/* --------------------------------------------------------------------------
   Section Common Typography
   -------------------------------------------------------------------------- */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 28px;
}

.section-title {
  font-size: 0.875rem;
  font-family: var(--font-mono);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.section-counter {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Selected Work — Editorial Rows
   -------------------------------------------------------------------------- */
.projects-list {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--border);
}

.project-row {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 32px;
  padding: 28px 0;
  border-bottom: 1px solid var(--border);
  transition: background-color var(--transition-fast);
}

.project-meta-col {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.project-name-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

.project-name {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.project-badge {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  padding: 2px 6px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border);
  background: var(--surface-subtle);
  color: var(--text-secondary);
}

.project-badge.live-badge {
  color: var(--live-indicator);
  border-color: rgba(5, 150, 105, 0.25);
  background: rgba(5, 150, 105, 0.05);
}

.project-role {
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
}

.project-links {
  margin-top: 4px;
}

.project-link-item {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-primary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1px;
}

.project-link-item:hover {
  border-color: var(--text-primary);
  color: var(--accent-blue);
}

.btn-arch-inspect {
  background: transparent;
  border: 1px dashed var(--border);
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  padding: 2px 6px;
  border-radius: var(--radius-xs);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: 6px;
  transition: all var(--transition-fast);
}

.btn-arch-inspect:hover {
  border-color: var(--text-primary);
  color: var(--text-primary);
  background: var(--surface-subtle);
}

.deepdive-target-slot {
  grid-column: 1 / -1;
}

.project-deepdive-panel {
  margin-top: 16px;
  padding: 20px;
  background: var(--surface-subtle);
  border: 1px solid var(--border);
  border-left: 3px solid var(--text-primary);
  border-radius: var(--radius-xs);
  animation: fadeIn 150ms ease-out;
}

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

.deepdive-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-subtle);
}

.deepdive-title-wrap {
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
}

.deepdive-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

.deepdive-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
}

.deepdive-close-btn {
  background: transparent;
  border: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 6px;
}

.deepdive-close-btn:hover {
  color: var(--text-primary);
}

.deepdive-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px 24px;
}

.deepdive-block h5 {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.deepdive-block p {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

@media (max-width: 600px) {
  .deepdive-grid {
    grid-template-columns: 1fr;
  }
}

.project-details-col {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.project-description {
  font-size: 0.9375rem;
  color: var(--text-primary);
  line-height: 1.6;
}

.project-contribution {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

.project-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 12px;
  margin-top: 4px;
}

.stack-item {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: -0.01em;
}

.stack-item::after {
  content: "·";
  margin-left: 12px;
  color: var(--border);
}

.stack-item:last-child::after {
  content: "";
  margin-left: 0;
}

/* --------------------------------------------------------------------------
   Experience Section — Chronological Timeline
   -------------------------------------------------------------------------- */
.timeline-list {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--border);
}

.timeline-row {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 32px;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
}

.timeline-meta-col {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.timeline-period {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-primary);
  font-weight: 500;
  letter-spacing: -0.01em;
}

.timeline-location {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

.timeline-content-col {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.timeline-role-title {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--text-primary);
}

.timeline-company {
  font-weight: 400;
  color: var(--text-secondary);
}

.timeline-company a {
  border-bottom: 1px solid var(--border);
  padding-bottom: 1px;
}

.timeline-company a:hover {
  border-color: var(--text-primary);
}

.timeline-summary {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.timeline-points {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 4px;
}

.timeline-point {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.55;
  position: relative;
  padding-left: 14px;
}

.timeline-point::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--text-muted);
}

/* Education Sub-block inside Experience */
.education-block {
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px dashed var(--border);
}

.education-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 16px;
}

/* --------------------------------------------------------------------------
   Technical Interests & Core Competencies
   -------------------------------------------------------------------------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px 40px;
  border-top: 1px solid var(--border);
  padding-top: 28px;
}

.skill-category {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.skill-category-name {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

.skill-items-list {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.skill-focus-note {
  grid-column: 1 / -1;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-subtle);
  padding-top: 16px;
  margin-top: 8px;
  line-height: 1.5;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.site-footer {
  margin-top: var(--section-spacing);
  padding: 40px 0 60px 0;
  border-top: 1px solid var(--border);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.footer-heading {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.footer-links-group {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px 24px;
}

.footer-link {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

.footer-copy-utility {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.btn-inline-copy {
  background: transparent;
  border: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  text-decoration: underline;
  cursor: pointer;
  padding: 0;
}

.btn-inline-copy:hover {
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
   Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 768px) {
  :root {
    --container-px: 20px;
    --section-spacing: var(--section-spacing-mobile);
  }

  .site-header {
    padding-top: 24px;
    padding-bottom: 20px;
  }

  .header-inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }

  .site-nav {
    width: 100%;
    overflow-x: auto;
    gap: 16px;
    padding-bottom: 4px;
    -webkit-overflow-scrolling: touch;
  }

  .nav-link {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
  }

  .intro-name {
    font-size: 1.75rem;
  }

  .intro-headline {
    font-size: 1.125rem;
  }

  .intro-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .action-btn {
    justify-content: center;
    min-height: 44px;
  }

  .project-row {
    grid-template-columns: 1fr;
    gap: 16px;
    padding: 24px 0;
  }

  .timeline-row {
    grid-template-columns: 1fr;
    gap: 12px;
    padding: 20px 0;
  }

  .skills-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .footer-top {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
}

/* Ultra small devices (320px - 360px) */
@media (max-width: 360px) {
  .site-brand {
    font-size: 1rem;
  }
  .intro-name {
    font-size: 1.5rem;
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Print Styles */
@media print {
  body {
    background: #FFFFFF;
    color: #000000;
  }
  .site-header, .theme-toggle-btn, .footer-bottom, .intro-actions {
    display: none;
  }
  .section-divider {
    border-color: #000000;
  }
}