/* =========================================================================
   Sharath — Portfolio Design System
   Derived from Bridge's "Trust-Ledger Modern" system (DESIGN_GUIDE.md v1.1),
   adapted for a personal engineering portfolio: same ink/emerald token
   language and precision-over-decoration principle, tuned with a warmer
   ink-950 headline weight, an ink-based (not emerald) primary button so the
   one emerald accent in this shell reads as deliberate, and a wider
   editorial content column for case-study prose.
   ========================================================================= */

:root {
  /* Neutrals — ink scale (slate-based) */
  --ink-950: #0B1220;
  --ink-900: #0F172A;
  --ink-700: #334155;
  --ink-500: #64748B;
  --ink-400: #94A3B8;
  --ink-300: #CBD5E1;
  --ink-200: #E2E8F0;
  --ink-100: #F1F5F9;
  --ink-50:  #F8FAFC;

  /* Surfaces */
  --canvas: #FAFAF9;
  --surface: #FFFFFF;
  --surface-sunken: #F5F5F4;
  --surface-overlay: rgba(15, 23, 42, .48);

  /* Brand: Emerald — the one accent, used deliberately and sparingly */
  --brand-700: #047857;
  --brand-600: #059669;
  --brand-500: #10B981;
  --brand-100: #D1FAE5;
  --brand-50:  #ECFDF5;

  /* Brass — secondary accent for highlights/metrics */
  --brass-600: #B45309;
  --brass-100: #FEF3C7;

  /* Semantic */
  --danger-600: #DC2626;
  --danger-50:  #FEF2F2;
  --info-600: #0369A1;
  --info-50:  #F0F9FF;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --radius-full: 999px;

  /* Shadows — quiet, cool-tinted */
  --shadow-xs: 0 1px 2px rgba(15, 23, 42, .05);
  --shadow-sm: 0 2px 8px rgba(15, 23, 42, .06);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, .10);
  --shadow-lg: 0 16px 48px rgba(15, 23, 42, .16);

  /* Motion */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 120ms;
  --dur-base: 200ms;
  --dur-slow: 320ms;

  /* Type */
  --font-display: "Inter", system-ui, sans-serif;
  --font-body: "Inter", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;

  /* Layout */
  --container-max: 1120px;
  --content-max: 720px;
  --header-h: 72px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --canvas: #0B1220;
    --surface: #101827;
    --surface-sunken: #0D1420;
    --ink-950: #F8FAFC;
    --ink-900: #F1F5F9;
    --ink-700: #CBD5E1;
    --ink-500: #94A3B8;
    --ink-400: #64748B;
    --ink-300: #334155;
    --ink-200: #1E293B;
    --ink-100: #17202E;
    --ink-50: #131B27;
    --brand-50: rgba(16, 185, 129, 0.12);
    --brand-100: rgba(16, 185, 129, 0.20);
    --surface-overlay: rgba(2, 6, 15, .6);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--canvas);
  color: var(--ink-900);
  font: 400 16px/1.6 var(--font-body);
  -webkit-font-smoothing: antialiased;
}

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

.tnum { font-variant-numeric: tabular-nums lining-nums; }

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

::selection { background: var(--brand-100); color: var(--brand-700); }

/* ---------- Typography ---------- */

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink-950);
  line-height: 1.15;
  margin: 0 0 .5em;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.25rem, 4vw, 3.25rem); font-weight: 700; max-width: 20ch; }
h2 { font-size: clamp(1.5rem, 2.6vw, 2rem); font-weight: 650; max-width: 22ch; }
h3 { font-size: 1.2rem; font-weight: 600; }
h4 { font-size: 1rem; font-weight: 600; }

p { max-width: 65ch; color: var(--ink-700); }

.lede {
  font-size: 1.15rem;
  line-height: 1.65;
  color: var(--ink-700);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--brand-700);
}

.muted { color: var(--ink-500); }

/* ---------- Layout ---------- */

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding-inline: 24px;
}

.content {
  max-width: var(--content-max);
  margin: 0 auto;
  padding-inline: 24px;
}

section { padding-block: 80px; }
@media (max-width: 768px) { section { padding-block: 48px; } }

.section-head { max-width: 640px; margin-bottom: 40px; }

hr.hairline {
  border: 0;
  border-top: 1px solid var(--ink-200);
  margin: 0;
}

/* ---------- Header / Nav ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  display: flex;
  align-items: center;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: saturate(150%) blur(8px);
  border-bottom: 1px solid var(--ink-200);
}

.site-header .container {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.wordmark {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--ink-950);
  letter-spacing: -0.02em;
}

.wordmark .mark {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--ink-950);
  color: var(--brand-500);
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: .8rem;
}

.wordmark .role {
  color: var(--ink-500);
  font-weight: 500;
  font-size: .85rem;
  border-left: 1px solid var(--ink-200);
  padding-left: 10px;
  margin-left: 2px;
}
@media (max-width: 640px) { .wordmark .role { display: none; } }

.header-actions {
  display: flex;
  align-items: center;
  gap: 20px;
  position: relative;
}

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

.site-nav a {
  font-size: .9rem;
  font-weight: 500;
  color: var(--ink-700);
  transition: color var(--dur-fast) var(--ease-out);
}
.site-nav a:hover { color: var(--ink-950); }
.site-nav a.active { color: var(--ink-950); font-weight: 600; }

.nav-toggle-input { display: none; }
.nav-toggle-btn { display: none; }

@media (max-width: 720px) {
  .nav-toggle-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    cursor: pointer;
    color: var(--ink-900);
  }
  .nav-toggle-btn:hover { background: var(--ink-100); }
  .nav-toggle-btn svg { width: 20px; height: 20px; }
  .nav-toggle-btn .icon-close { display: none; }
  .nav-toggle-input:checked ~ .nav-toggle-btn .icon-menu { display: none; }
  .nav-toggle-input:checked ~ .nav-toggle-btn .icon-close { display: block; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    right: 0;
    left: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--ink-200);
    box-shadow: var(--shadow-md);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--dur-base) var(--ease-out);
  }
  .nav-toggle-input:checked ~ .site-nav { max-height: 260px; }
  .site-nav a {
    padding: 16px 24px;
    border-top: 1px solid var(--ink-100);
    font-size: 1rem;
  }
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 44px;
  padding-inline: 20px;
  border-radius: var(--radius-md);
  font-size: .9rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
  white-space: nowrap;
}
.btn svg { width: 16px; height: 16px; }

.btn.primary {
  background: var(--ink-950);
  color: var(--surface);
}
.btn.primary:hover { background: var(--ink-700); }
.btn.primary:active { transform: translateY(1px); }

.btn.secondary {
  background: var(--surface);
  border-color: var(--ink-300);
  color: var(--ink-900);
}
.btn.secondary:hover { background: var(--ink-50); border-color: var(--ink-400); }

.btn.ghost {
  background: transparent;
  color: var(--ink-700);
}
.btn.ghost:hover { background: var(--ink-100); }

.btn.sm { height: 36px; padding-inline: 14px; font-size: .82rem; }
.btn.lg { height: 52px; padding-inline: 26px; font-size: .95rem; }

/* ---------- Cards ---------- */

.card {
  background: var(--surface);
  border: 1px solid var(--ink-200);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xs);
}

.card--hover { transition: transform var(--dur-base) var(--ease-out), box-shadow var(--dur-base) var(--ease-out); }
.card--hover:hover { transform: translateY(-2px); box-shadow: var(--shadow-sm); }

/* ---------- Badges / Tags ---------- */

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: .75rem;
  font-weight: 600;
  background: var(--ink-100);
  color: var(--ink-700);
}

.tag--brand { background: var(--brand-50); color: var(--brand-700); }
.tag--brass { background: var(--brass-100); color: var(--brass-600); }
.tag--outline { background: transparent; border: 1px solid var(--ink-300); color: var(--ink-700); }

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; }

/* ---------- Hero ---------- */

.hero {
  padding-top: 64px;
  padding-bottom: 72px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr .9fr;
  gap: 64px;
  align-items: center;
}
@media (max-width: 900px) { .hero-grid { grid-template-columns: 1fr; gap: 40px; } }

.hero h1 { margin-top: 14px; margin-bottom: 20px; }
.hero .lede { margin-bottom: 32px; }

.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 40px; }

/* Stat row */

.stat-row {
  display: flex;
  gap: 32px;
  flex-wrap: wrap;
  padding-top: 24px;
  border-top: 1px solid var(--ink-200);
}

.stat-item .value {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink-950);
}
.stat-item .label {
  font-size: .78rem;
  color: var(--ink-500);
  margin-top: 2px;
}

/* Hero visual: abstract architecture card */

.hero-visual {
  background: var(--surface);
  border: 1px solid var(--ink-200);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  padding: 20px;
}

.hero-visual .visual-titlebar {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
}
.hero-visual .dot { width: 9px; height: 9px; border-radius: 50%; background: var(--ink-200); }
.hero-visual .visual-label {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: .7rem;
  color: var(--ink-400);
}

/* ---------- Skill / stack grid ---------- */

.stack-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
}

.stack-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 16px;
  border: 1px solid var(--ink-200);
  border-radius: var(--radius-md);
  background: var(--surface);
  font-size: .85rem;
  font-weight: 500;
  color: var(--ink-700);
}
.stack-item .dot-icon { width: 8px; height: 8px; border-radius: 50%; background: var(--brand-500); flex-shrink: 0; }

/* ---------- Project cards ---------- */

.project-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}
@media (max-width: 800px) { .project-grid { grid-template-columns: 1fr; } }

.capability-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
@media (max-width: 900px) { .capability-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .capability-grid { grid-template-columns: 1fr; } }

.project-card {
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.project-card .kicker {
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--ink-500);
}

.project-card h3 { margin-bottom: 0; }
.project-card p { font-size: .92rem; margin: 0; }

.project-card .metrics {
  display: flex;
  gap: 20px;
  padding-top: 10px;
  border-top: 1px solid var(--ink-100);
  margin-top: auto;
}
.project-card .metrics .m-value {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--ink-950);
}
.project-card .metrics .m-label { font-size: .72rem; color: var(--ink-500); }

.project-card .card-links { display: flex; gap: 16px; margin-top: 4px; }
.project-card .card-links a {
  font-size: .85rem;
  font-weight: 600;
  color: var(--brand-700);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.project-card .card-links a:hover { color: var(--brand-600); }
.project-card .card-links a svg { width: 14px; height: 14px; }

/* Featured (flagship) card */

.featured-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
  overflow: hidden;
}
@media (max-width: 860px) { .featured-card { grid-template-columns: 1fr; } }

.featured-card .fc-body { padding: 40px; display: flex; flex-direction: column; gap: 18px; }
.featured-card .fc-visual {
  background: var(--ink-950);
  padding: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ---------- Timeline (case study) ---------- */

.timeline { display: flex; flex-direction: column; }

.timeline-item {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 20px;
  padding-bottom: 32px;
  position: relative;
}
.timeline-item:not(:last-child)::before {
  content: "";
  position: absolute;
  left: 13px;
  top: 28px;
  bottom: 0;
  width: 1px;
  background: var(--ink-200);
}
.timeline-node {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--brand-50);
  border: 1px solid var(--brand-100);
  color: var(--brand-700);
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: .7rem;
  font-weight: 700;
  flex-shrink: 0;
}

/* ---------- Architecture diagram (SVG wrapper) ---------- */

.diagram-card {
  padding: 28px;
  overflow-x: auto;
}

/* ---------- KPI strip ---------- */

.kpi-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1px;
  background: var(--ink-200);
  border: 1px solid var(--ink-200);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.kpi-cell {
  background: var(--surface);
  padding: 20px;
}
.kpi-cell .value {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--ink-950);
}
.kpi-cell .label { font-size: .78rem; color: var(--ink-500); margin-top: 4px; }

/* ---------- Callout ---------- */

.callout {
  display: flex;
  gap: 14px;
  padding: 18px 20px;
  border-radius: var(--radius-md);
  border: 1px solid var(--brand-100);
  background: var(--brand-50);
  font-size: .9rem;
  color: var(--brand-700);
}
.callout svg { width: 20px; height: 20px; flex-shrink: 0; margin-top: 1px; }
.callout p { color: inherit; margin: 0; max-width: none; }

.callout--info { border-color: var(--info-50); background: var(--info-50); color: var(--info-600); }

/* ---------- CTA band ---------- */

.cta-band {
  background: var(--ink-950);
  border-radius: var(--radius-xl);
  padding: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  color: var(--surface);
}
.cta-band h2 { color: var(--surface); margin-bottom: 6px; }
.cta-band p { color: var(--ink-300); margin: 0; }
.cta-band .btn.primary { background: var(--brand-600); }
.cta-band .btn.primary:hover { background: var(--brand-500); }

/* ---------- Footer ---------- */

.site-footer {
  border-top: 1px solid var(--ink-200);
  background: var(--surface-sunken);
  padding-block: 48px;
}
.footer-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}
.footer-links { display: flex; gap: 24px; }
.footer-links a { font-size: .85rem; color: var(--ink-500); }
.footer-links a:hover { color: var(--ink-900); }
.footer-note { font-size: .8rem; color: var(--ink-400); }

/* ---------- Case-study prose page ---------- */

.case-hero {
  padding-block: 56px 40px;
  border-bottom: 1px solid var(--ink-200);
}

.case-meta {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--ink-200);
}
.case-meta .item .k { font-size: .72rem; text-transform: uppercase; letter-spacing: .05em; color: var(--ink-500); }
.case-meta .item .v { font-size: .92rem; font-weight: 600; color: var(--ink-900); margin-top: 2px; }

.prose h2 { margin-top: 2.4em; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { margin-top: 1.8em; }
.prose p, .prose ul { color: var(--ink-700); font-size: 1rem; }
.prose ul { padding-left: 1.2em; }
.prose li { margin-bottom: .5em; }
.prose strong { color: var(--ink-900); }
.prose code {
  font-family: var(--font-mono);
  font-size: .85em;
  background: var(--ink-100);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--ink-900);
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: .85rem;
  font-weight: 600;
  color: var(--ink-500);
  margin-bottom: 24px;
}
.back-link:hover { color: var(--ink-900); }
.back-link svg { width: 14px; height: 14px; }

/* ---------- Utility ---------- */

.mt-0 { margin-top: 0; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
@media (max-width: 800px) { .grid-2 { grid-template-columns: 1fr; gap: 24px; } }

.reveal { opacity: 0; transform: translateY(12px); transition: opacity .5s var(--ease-out), transform .5s var(--ease-out); }
.reveal.is-visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; scroll-behavior: auto !important; }
}