/* ---------------------------------------------------------------------------
   Nimit Jain — Portfolio & Quantitative Engineering Showcase Design System
   Architecture: Engineering Notebook meets Production Systems Console
   Typography: Instrument Serif (Editorial Display) + Plus Jakarta Sans (Prose) + JetBrains Mono (Telemetry)
   Colors: High-contrast Dark Void, Precision Cyan, Mathematical Amber, Emerald, Ruby
   Motion: Physics-based cubic-bezier transitions + CSS 3D perspective transforms
--------------------------------------------------------------------------- */

@import url('https://fonts.googleapis.com/css2?family=Instrument+Serif:ital@0;1&family=JetBrains+Mono:ital,wght@0,400;0,500;0,600;1,400&family=Plus+Jakarta+Sans:wght@400;500;600;700&display=swap');

:root {
  --font-serif: 'Instrument Serif', Georgia, serif;
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Default Dark Mode: Deep Engineered Void */
  --bg: #090b0e;
  --bg-grid: rgba(255, 255, 255, 0.025);
  --surface: #11151d;
  --surface-2: #171d28;
  --surface-3: #1f2736;
  --surface-hover: #263042;
  
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);
  --border-accent: rgba(56, 189, 248, 0.4);

  --text: #f8fafc;
  --text-2: #cbd5e1;
  --text-3: #94a3b8;
  --text-muted: #64748b;

  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.1);
  --accent-glow: rgba(56, 189, 248, 0.25);
  --accent-text: #042f44;

  --amber: #f59e0b;
  --amber-soft: rgba(245, 158, 11, 0.12);
  --amber-border: rgba(245, 158, 11, 0.35);

  --good: #10b981;
  --good-soft: rgba(16, 185, 129, 0.12);
  --good-border: rgba(16, 185, 129, 0.35);

  --bad: #ef4444;
  --bad-soft: rgba(239, 68, 68, 0.12);
  --bad-border: rgba(239, 68, 68, 0.35);

  --radius: 6px;
  --radius-sm: 4px;
  --radius-pill: 9999px;
  --maxw: 1140px;
  --transition-fast: 0.15s ease;
  --transition-smooth: 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

:root[data-theme="light"] {
  --bg: #f8fafc;
  --bg-grid: rgba(0, 0, 0, 0.03);
  --surface: #ffffff;
  --surface-2: #f1f5f9;
  --surface-3: #e2e8f0;
  --surface-hover: #cbd5e1;

  --border: rgba(0, 0, 0, 0.08);
  --border-strong: rgba(0, 0, 0, 0.16);
  --border-accent: rgba(2, 132, 199, 0.4);

  --text: #0f172a;
  --text-2: #334155;
  --text-3: #64748b;
  --text-muted: #94a3b8;

  --accent: #0284c7;
  --accent-soft: rgba(2, 132, 199, 0.08);
  --accent-glow: rgba(2, 132, 199, 0.2);
  --accent-text: #ffffff;

  --amber: #d97706;
  --amber-soft: rgba(217, 119, 6, 0.08);
  --amber-border: rgba(217, 119, 6, 0.3);

  --good: #059669;
  --good-soft: rgba(5, 150, 105, 0.08);
  --good-border: rgba(5, 150, 105, 0.3);

  --bad: #dc2626;
  --bad-soft: rgba(220, 38, 38, 0.08);
  --bad-border: rgba(220, 38, 38, 0.3);
}

/* --- Base & Reset -------------------------------------------------------- */

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  background-color: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  background-image: 
    linear-gradient(var(--bg-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--bg-grid) 1px, transparent 1px);
  background-size: 32px 32px;
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography Hierarchy */

h1, h2, h3, h4, h5, h6 {
  color: var(--text);
  margin-top: 0;
  line-height: 1.15;
}

h1 {
  font-family: var(--font-serif);
  font-weight: 400;
  font-size: clamp(2.4rem, 5.5vw, 4rem);
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

h2 {
  font-family: var(--font-serif);
  font-weight: 400;
  font-size: clamp(1.8rem, 3.5vw, 2.75rem);
  letter-spacing: -0.015em;
  margin-bottom: 0.75rem;
}

h3 {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1.2rem;
  letter-spacing: -0.01em;
  margin-bottom: 0.5rem;
}

p {
  margin-top: 0;
  margin-bottom: 1.25rem;
  color: var(--text-2);
}

.lede {
  font-size: clamp(1.05rem, 1.8vw, 1.25rem);
  line-height: 1.6;
  color: var(--text-2);
  font-weight: 400;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.5rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.eyebrow::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  background: var(--accent);
  border-radius: 50%;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

.small { font-size: 0.875rem; }
.xs { font-size: 0.75rem; }
.muted { color: var(--text-3); }

code, pre {
  font-family: var(--font-mono);
  font-size: 0.85em;
}

code {
  background: var(--surface-2);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  color: var(--accent);
}

pre {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 1.2rem;
  border-radius: var(--radius);
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--text-2);
}

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

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

/* Layout Utilities */

.wrap {
  width: 100%;
  max-width: var(--maxw);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

section {
  padding: 4.5rem 0;
  border-bottom: 1px solid var(--border);
  position: relative;
}

section:last-of-type {
  border-bottom: none;
}

.row {
  display: flex;
  align-items: center;
}

.between { justify-content: space-between; }
.center { justify-content: center; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }

.grid {
  display: grid;
  gap: 1.25rem;
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }

@media (max-width: 768px) {
  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }
  section {
    padding: 3rem 0;
  }
}

/* Navigation Bar */

.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(9, 11, 14, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

:root[data-theme="light"] .nav {
  background: rgba(248, 250, 252, 0.88);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3.75rem;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 1.5rem;
  font-size: 0.875rem;
}

.brand {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  color: var(--text);
  font-weight: 400;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

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

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.nav-link {
  color: var(--text-3);
  font-weight: 500;
  padding: 0.4rem 0.2rem;
  border-bottom: 2px solid transparent;
  transition: all var(--transition-fast);
}

.nav-link:hover, .nav-link.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

.theme-toggle {
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-2);
  width: 2rem;
  height: 2rem;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--text);
  border-color: var(--border-strong);
}

/* Cards & Components */

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  position: relative;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}

.card:hover {
  border-color: var(--border-strong);
}

.card-link {
  display: block;
  color: inherit;
}

.card-link:hover {
  border-color: var(--border-accent);
  background: var(--surface-2);
}

/* Metric / Stat Card */

.card.stat {
  padding: 1.2rem;
  display: flex;
  flex-direction: column;
}

.card.stat .label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-3);
  margin-bottom: 0.4rem;
}

.card.stat .value {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--text);
  line-height: 1.1;
  letter-spacing: -0.02em;
}

.card.stat .sub {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

/* Pills & Badges */

.pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-family: var(--font-mono);
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-2);
  white-space: nowrap;
}

.pill.accent {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 500;
}

.pill.good {
  background: var(--good-soft);
  border-color: var(--good);
  color: var(--good);
}

.pill.amber {
  background: var(--amber-soft);
  border-color: var(--amber);
  color: var(--amber);
}

.pill.bad {
  background: var(--bad-soft);
  border-color: var(--bad);
  color: var(--bad);
}

.badge {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  background: var(--surface-3);
  border: 1px solid var(--border);
  color: var(--text-2);
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  font-family: var(--font-sans);
  background: var(--accent);
  color: var(--accent-text);
  text-decoration: none;
}

.btn:hover {
  filter: brightness(1.1);
  color: var(--accent-text);
  box-shadow: 0 0 16px var(--accent-glow);
}

.btn-outline {
  background: var(--surface);
  border-color: var(--border-strong);
  color: var(--text);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: none;
}

.btn-sm {
  padding: 0.35rem 0.75rem;
  font-size: 0.78rem;
}

/* Callouts & Notes */

.callout {
  padding: 1.25rem;
  border-radius: var(--radius);
  border-left: 3px solid var(--accent);
  background: var(--surface);
  margin: 1.5rem 0;
  font-size: 0.9rem;
}

.callout.warn {
  border-left-color: var(--amber);
  background: var(--amber-soft);
}

.callout.bad {
  border-left-color: var(--bad);
  background: var(--bad-soft);
}

/* Tables */

.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin: 1.25rem 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  text-align: left;
}

th, td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
}

th {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-3);
  background: var(--surface-2);
}

tr:last-child td {
  border-bottom: none;
}

td.num, th.num {
  text-align: right;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

/* Interactive Workbench & Forms */

.workbench {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 2rem 0;
}

.workbench-header {
  padding: 1rem 1.5rem;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.workbench-body {
  padding: 1.5rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1.25rem;
}

.control-group label {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-2);
  display: flex;
  justify-content: space-between;
}

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  background: var(--surface-3);
  border-radius: 3px;
  outline: none;
  border: 1px solid var(--border);
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 2px solid var(--surface);
  box-shadow: 0 0 8px var(--accent-glow);
  transition: transform var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

select {
  background: var(--surface-2);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 0.6rem 0.8rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  outline: none;
}

select:focus {
  border-color: var(--accent);
}

/* ===========================================================================
   3D Interactive Career Resume Centerpiece (CSS 3D Engine)
=========================================================================== */

.career-viewport {
  position: relative;
  perspective: 1400px;
  perspective-origin: 50% 30%;
  padding: 2rem 0;
  overflow: visible;
}

.career-track {
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--transition-smooth);
  display: flex;
  flex-direction: column;
  gap: 3rem;
}

.waypoint-node {
  transform-style: preserve-3d;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 2rem;
  position: relative;
  transition: transform var(--transition-smooth), border-color var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.waypoint-node.active-focus {
  border-color: var(--accent);
  box-shadow: 0 0 30px var(--accent-glow), 0 15px 40px rgba(0, 0, 0, 0.6);
  transform: translateZ(40px);
}

.waypoint-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1.2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1rem;
}

.waypoint-meta {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent);
}

.waypoint-org {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text);
  margin-top: 0.2rem;
}

.waypoint-highlights {
  list-style: none;
  padding-left: 0;
  margin: 0 0 1.5rem 0;
}

.waypoint-highlights li {
  position: relative;
  padding-left: 1.5rem;
  margin-bottom: 0.75rem;
  font-size: 0.92rem;
  color: var(--text-2);
}

.waypoint-highlights li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-family: var(--font-mono);
}

.waypoint-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

/* Timeline Interactive Scrubber */

.timeline-scrubber {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  padding: 0.4rem;
  margin-bottom: 2.5rem;
}

.scrub-btn {
  background: none;
  border: none;
  color: var(--text-3);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.45rem 1rem;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.scrub-btn:hover {
  color: var(--text);
}

.scrub-btn.active {
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 600;
}

/* KaTeX Overrides & Polish */

.katex {
  font-size: 1.05em !important;
  color: var(--text);
}

.katex-display {
  margin: 1.25rem 0 !important;
  padding: 0.75rem !important;
  background: var(--surface-2);
  border-radius: var(--radius-sm);
  border-left: 2px solid var(--accent);
  overflow-x: auto;
  overflow-y: hidden;
}

/* Footer */

footer {
  margin-top: auto;
  padding: 3rem 0;
  border-top: 1px solid var(--border);
  background: var(--surface);
  font-size: 0.85rem;
  color: var(--text-3);
}

footer a {
  color: var(--text-2);
}

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