/* ============================================================
   Chia Kang Yee — Portfolio
   Concept: technical AI/automation consultant.
   Cool ink surfaces + a precise cyan-teal accent. Mono accents
   for engineering credibility. Light + dark mode.
   ============================================================ */

/* ---------- Design tokens ---------- */
:root {
  /* Type scale (fluid) */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3.5rem);
  --text-3xl: clamp(2.5rem, 1rem + 4vw, 5rem);

  /* Spacing */
  --space-1: 0.25rem;  --space-2: 0.5rem;  --space-3: 0.75rem; --space-4: 1rem;
  --space-5: 1.25rem;  --space-6: 1.5rem;  --space-8: 2rem;    --space-10: 2.5rem;
  --space-12: 3rem;    --space-16: 4rem;   --space-20: 5rem;   --space-24: 6rem;
  --space-32: 8rem;

  /* Radius */
  --radius-sm: 0.375rem; --radius-md: 0.5rem; --radius-lg: 0.875rem; --radius-xl: 1.25rem;
  --radius-full: 9999px;

  --transition-interactive: 200ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Fonts */
  --font-display: 'General Sans', 'Satoshi', system-ui, sans-serif;
  --font-body: 'Satoshi', 'Inter', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SF Mono', monospace;

  /* Content widths */
  --content-wide: 1140px;
}

/* ---------- Dark mode (default for this brand) ---------- */
:root,
[data-theme='dark'] {
  --color-bg: #0b0f14;
  --color-surface: #11161d;
  --color-surface-2: #161c24;
  --color-surface-offset: #1b232d;
  --color-border: #232c37;
  --color-border-strong: #2f3a47;

  --color-text: #e7edf3;
  --color-text-muted: #9aa6b3;
  --color-text-faint: #5d6975;
  --color-text-inverse: #07120f;

  --color-primary: #36e0c0;       /* cyan-teal accent */
  --color-primary-hover: #5cf0d3;
  --color-primary-soft: rgba(54, 224, 192, 0.12);
  --color-primary-line: rgba(54, 224, 192, 0.32);

  --grid-line: rgba(255, 255, 255, 0.03);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 20px 48px rgba(0, 0, 0, 0.5);
  --glow: 0 0 0 1px var(--color-primary-line), 0 8px 32px rgba(54, 224, 192, 0.14);
}

/* ---------- Light mode ---------- */
[data-theme='light'] {
  --color-bg: #f6f8fa;
  --color-surface: #ffffff;
  --color-surface-2: #f1f4f7;
  --color-surface-offset: #eaeef2;
  --color-border: #dfe5ec;
  --color-border-strong: #cad3dd;

  --color-text: #0d1620;
  --color-text-muted: #56636f;
  --color-text-faint: #97a2ad;
  --color-text-inverse: #ffffff;

  --color-primary: #0a8f78;
  --color-primary-hover: #0b7666;
  --color-primary-soft: rgba(10, 143, 120, 0.10);
  --color-primary-line: rgba(10, 143, 120, 0.28);

  --grid-line: rgba(13, 22, 32, 0.04);
  --shadow-md: 0 8px 24px rgba(13, 22, 32, 0.08);
  --shadow-lg: 0 20px 48px rgba(13, 22, 32, 0.12);
  --glow: 0 0 0 1px var(--color-primary-line), 0 8px 28px rgba(10, 143, 120, 0.12);
}

/* System preference fallback if no manual toggle yet */
@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --color-bg: #f6f8fa; --color-surface: #ffffff; --color-surface-2: #f1f4f7;
    --color-surface-offset: #eaeef2; --color-border: #dfe5ec; --color-border-strong: #cad3dd;
    --color-text: #0d1620; --color-text-muted: #56636f; --color-text-faint: #97a2ad;
    --color-primary: #0a8f78; --color-primary-hover: #0b7666;
    --color-primary-soft: rgba(10,143,120,0.10); --color-primary-line: rgba(10,143,120,0.28);
    --grid-line: rgba(13,22,32,0.04);
  }
}

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

html {
  -webkit-text-size-adjust: none; text-size-adjust: none;
  -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}

img, svg { display: block; max-width: 100%; height: auto; }
ul[role='list'] { list-style: none; }
button { cursor: pointer; background: none; border: none; color: inherit; font: inherit; }

h1, h2, h3, h4 { text-wrap: balance; line-height: 1.12; font-family: var(--font-display); font-weight: 600; }
p { text-wrap: pretty; }

::selection { background: var(--color-primary-soft); color: var(--color-text); }

:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 3px; border-radius: var(--radius-sm); }

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

a, button, .filter, .case__toggle {
  transition: color var(--transition-interactive), background var(--transition-interactive),
    border-color var(--transition-interactive), box-shadow var(--transition-interactive),
    transform var(--transition-interactive);
}

.skip-link {
  position: absolute; left: var(--space-4); top: -100px; z-index: 200;
  background: var(--color-primary); color: var(--color-text-inverse);
  padding: var(--space-2) var(--space-4); border-radius: var(--radius-md); font-weight: 600;
}
.skip-link:focus { top: var(--space-4); }

.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;
}

/* ---------- Layout ---------- */
.container { width: 100%; max-width: var(--content-wide); margin-inline: auto; padding-inline: var(--space-6); }

.section { padding-block: clamp(var(--space-16), 9vw, var(--space-32)); }
.section--alt { background: var(--color-surface); border-block: 1px solid var(--color-border); }

.section__head { max-width: 56ch; margin-bottom: var(--space-12); }
.section__title { font-size: var(--text-xl); margin-top: var(--space-2); letter-spacing: -0.01em; }
.section__sub { color: var(--color-text-muted); margin-top: var(--space-4); font-size: var(--text-base); }

.eyebrow {
  font-family: var(--font-mono); font-size: var(--text-xs); text-transform: uppercase;
  letter-spacing: 0.18em; color: var(--color-primary); font-weight: 500;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--space-2);
  font-weight: 600; font-size: var(--text-sm); line-height: 1;
  padding: var(--space-3) var(--space-5); border-radius: var(--radius-full);
  border: 1px solid transparent; white-space: nowrap;
}
.btn--lg { padding: var(--space-4) var(--space-8); font-size: var(--text-base); }
.btn--small { padding: var(--space-2) var(--space-4); }
.btn--primary { background: var(--color-primary); color: var(--color-text-inverse); }
.btn--primary:hover { background: var(--color-primary-hover); transform: translateY(-2px); box-shadow: var(--glow); }
.btn--ghost { background: transparent; color: var(--color-text); border-color: var(--color-border-strong); }
.btn--ghost:hover { border-color: var(--color-primary); color: var(--color-primary); transform: translateY(-2px); }

/* ---------- Header ---------- */
.header {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--color-bg) 82%, transparent);
  backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-interactive), background var(--transition-interactive);
}
.header.is-scrolled { border-bottom-color: var(--color-border); }
.header__inner { display: flex; align-items: center; justify-content: space-between; gap: var(--space-6); height: 4.25rem; }

.brand { display: inline-flex; align-items: center; gap: var(--space-3); font-family: var(--font-display); font-weight: 600; }
.brand__mark { color: var(--color-text); --mark-accent: var(--color-primary); display: inline-flex; }
.brand__text { font-size: var(--text-base); letter-spacing: -0.01em; }

.nav { display: none; gap: var(--space-6); }
.nav a { font-size: var(--text-sm); color: var(--color-text-muted); font-weight: 500; }
.nav a:hover { color: var(--color-text); }

.header__actions { display: flex; align-items: center; gap: var(--space-3); }
.header__actions .btn--small { display: none; }

.theme-toggle {
  display: inline-flex; align-items: center; justify-content: center;
  width: 2.25rem; height: 2.25rem; border-radius: var(--radius-full);
  border: 1px solid var(--color-border-strong); color: var(--color-text-muted);
}
.theme-toggle:hover { color: var(--color-primary); border-color: var(--color-primary); }

@media (min-width: 860px) {
  .nav { display: flex; }
  .header__actions .btn--small { display: inline-flex; }
}

/* ---------- Hero ---------- */
.hero { position: relative; overflow: hidden; padding-block: clamp(var(--space-20), 14vw, var(--space-32)); }
.hero__grid-bg {
  position: absolute; inset: 0; z-index: 0; pointer-events: none;
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: radial-gradient(120% 90% at 70% 0%, #000 35%, transparent 78%);
  mask-image: radial-gradient(120% 90% at 70% 0%, #000 35%, transparent 78%);
}
.hero__inner { position: relative; z-index: 1; max-width: 56rem; }
.hero__title {
  font-size: var(--text-3xl); letter-spacing: -0.025em; margin-top: var(--space-5);
  font-weight: 600;
}
.hero__accent { display: block; color: var(--color-primary); }
.hero__lead { color: var(--color-text-muted); font-size: var(--text-lg); max-width: 50ch; margin-top: var(--space-6); }
.hero__cta { display: flex; flex-wrap: wrap; gap: var(--space-3); margin-top: var(--space-8); }
.hero__links { display: flex; gap: var(--space-6); margin-top: var(--space-8); }
.hero__links a { font-family: var(--font-mono); font-size: var(--text-sm); color: var(--color-text-muted); }
.hero__links a:hover { color: var(--color-primary); }

/* ---------- Metrics ---------- */
.metrics { border-block: 1px solid var(--color-border); background: var(--color-surface); }
.metrics__grid {
  display: grid; grid-template-columns: 1fr; gap: 0;
}
.metric { padding: var(--space-8) 0; border-bottom: 1px solid var(--color-border); }
.metric:last-child { border-bottom: none; }
.metric__value {
  display: block; font-family: var(--font-display); font-weight: 700;
  font-size: var(--text-2xl); color: var(--color-primary); letter-spacing: -0.02em;
}
.metric__label { display: block; color: var(--color-text-muted); font-size: var(--text-sm); margin-top: var(--space-2); max-width: 30ch; }

@media (min-width: 720px) {
  .metrics__grid { grid-template-columns: repeat(2, 1fr); gap: var(--space-8) var(--space-12); }
  .metric { padding: var(--space-10) 0; }
  .metric:nth-last-child(-n+2) { border-bottom: none; }
}
@media (min-width: 1000px) {
  .metrics__grid { grid-template-columns: repeat(4, 1fr); }
  .metric { border-bottom: none; border-right: 1px solid var(--color-border); padding: var(--space-12) var(--space-8) var(--space-12) 0; }
  .metric:last-child { border-right: none; }
}

/* ---------- Filters ---------- */
.filters { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-bottom: var(--space-8); }
.filter {
  font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.04em;
  padding: var(--space-2) var(--space-4); border-radius: var(--radius-full);
  border: 1px solid var(--color-border-strong); color: var(--color-text-muted);
}
.filter:hover { color: var(--color-text); border-color: var(--color-text-faint); }
.filter.is-active { background: var(--color-primary-soft); color: var(--color-primary); border-color: var(--color-primary-line); }

/* ---------- Case cards ---------- */
.cases { display: flex; flex-direction: column; gap: var(--space-4); }
.case {
  border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  background: var(--color-surface); overflow: hidden;
  transition: border-color var(--transition-interactive), box-shadow var(--transition-interactive), opacity 300ms ease, transform 300ms ease;
}
.case:hover { border-color: var(--color-border-strong); }
.case.is-hidden { display: none; }
.case__toggle {
  width: 100%; display: grid; grid-template-columns: auto 1fr auto;
  align-items: center; gap: var(--space-4); text-align: left;
  padding: var(--space-5) var(--space-6);
}
.case__index { font-family: var(--font-mono); font-size: var(--text-sm); color: var(--color-text-faint); }
.case__title { font-size: var(--text-lg); }
.case__tagline { color: var(--color-text-muted); font-size: var(--text-sm); margin-top: var(--space-1); }
.case__chevron { width: 11px; height: 11px; border-right: 2px solid var(--color-text-muted); border-bottom: 2px solid var(--color-text-muted); transform: rotate(45deg); transition: transform var(--transition-interactive); margin-right: var(--space-1); }
.case__toggle[aria-expanded='true'] .case__chevron { transform: rotate(-135deg); }
.case__toggle:hover .case__title { color: var(--color-primary); }

.case__body { display: grid; grid-template-rows: 0fr; transition: grid-template-rows 320ms cubic-bezier(0.16, 1, 0.3, 1); }
.case__toggle[aria-expanded='true'] + .case__body { grid-template-rows: 1fr; }
.case__content { overflow: hidden; }
.case__content > * { padding-inline: var(--space-6); }
.case__content p { color: var(--color-text-muted); padding-top: var(--space-1); }
.case__content p:first-child { padding-left: calc(var(--space-6) + var(--space-4) + 1.5ch); } /* align under title on wide */
.case__content .tags { padding-bottom: var(--space-6); padding-top: var(--space-4); }

.tags { display: flex; flex-wrap: wrap; gap: var(--space-2); list-style: none; }
.tags li {
  font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-text-muted);
  padding: var(--space-1) var(--space-3); border: 1px solid var(--color-border);
  border-radius: var(--radius-full); background: var(--color-surface-2);
}

@media (max-width: 620px) {
  .case__content p:first-child { padding-left: var(--space-6); }
  .case__toggle { padding-inline: var(--space-5); }
  .case__content > * { padding-inline: var(--space-5); }
}

/* ---------- Timeline ---------- */
.timeline { list-style: none; display: flex; flex-direction: column; gap: var(--space-8); }
.timeline__item {
  display: grid; grid-template-columns: 1fr; gap: var(--space-3);
  padding-left: var(--space-6); border-left: 2px solid var(--color-border); position: relative;
}
.timeline__item::before {
  content: ''; position: absolute; left: -7px; top: 6px; width: 12px; height: 12px;
  border-radius: var(--radius-full); background: var(--color-bg); border: 2px solid var(--color-primary);
}
.timeline__meta { display: flex; flex-direction: column; }
.timeline__period { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-primary); letter-spacing: 0.04em; }
.timeline__loc { font-size: var(--text-xs); color: var(--color-text-faint); margin-top: var(--space-1); }
.timeline__role { font-size: var(--text-lg); }
.timeline__org { color: var(--color-text-muted); font-size: var(--text-sm); margin-top: var(--space-1); margin-bottom: var(--space-3); }
.timeline__body ul { list-style: none; display: flex; flex-direction: column; gap: var(--space-2); }
.timeline__body li { position: relative; padding-left: var(--space-5); color: var(--color-text-muted); font-size: var(--text-sm); max-width: 70ch; }
.timeline__body li::before { content: '—'; position: absolute; left: 0; color: var(--color-primary); }

@media (min-width: 820px) {
  .timeline__item { grid-template-columns: 13rem 1fr; gap: var(--space-8); padding-left: var(--space-8); }
}

/* ---------- Capabilities ---------- */
.caps__grid { display: grid; grid-template-columns: 1fr; gap: var(--space-4); }
.cap {
  padding: var(--space-6); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  background: var(--color-surface-2);
}
.cap:hover { border-color: var(--color-primary-line); }
.cap__title { font-size: var(--text-lg); margin-bottom: var(--space-3); }
.cap p { color: var(--color-text-muted); font-size: var(--text-sm); }
@media (min-width: 700px) { .caps__grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1000px) {
  .caps__grid { grid-template-columns: repeat(3, 1fr); }
  .cap:first-child { grid-column: span 1; }
}

/* ---------- Stack ---------- */
.stack__grid { display: grid; grid-template-columns: 1fr; gap: var(--space-10); }
.stack__label { font-family: var(--font-mono); font-size: var(--text-xs); text-transform: uppercase; letter-spacing: 0.14em; color: var(--color-text-faint); margin-bottom: var(--space-4); }
.chips { display: flex; flex-wrap: wrap; gap: var(--space-2); list-style: none; }
.chips li {
  font-size: var(--text-sm); color: var(--color-text); padding: var(--space-2) var(--space-4);
  border: 1px solid var(--color-border); border-radius: var(--radius-md); background: var(--color-bg);
}
@media (min-width: 700px) { .stack__grid { grid-template-columns: repeat(2, 1fr); gap: var(--space-12) var(--space-16); } }

/* ---------- Education ---------- */
.edu { list-style: none; display: flex; flex-direction: column; }
.edu__item { display: grid; grid-template-columns: 1fr; gap: var(--space-1); padding-block: var(--space-6); border-bottom: 1px solid var(--color-border); }
.edu__item:last-child { border-bottom: none; }
.edu__years { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-primary); }
.edu__school { font-size: var(--text-lg); }
.edu__detail p { color: var(--color-text-muted); font-size: var(--text-sm); margin-top: var(--space-1); }
@media (min-width: 700px) { .edu__item { grid-template-columns: 10rem 1fr; gap: var(--space-8); align-items: baseline; } }

/* ---------- Contact ---------- */
.contact__inner { max-width: 48rem; text-align: center; margin-inline: auto; }
.contact__title { font-size: var(--text-2xl); margin-top: var(--space-3); letter-spacing: -0.02em; }
.contact__lead { color: var(--color-text-muted); font-size: var(--text-lg); margin-top: var(--space-5); }
.contact__cta { display: flex; flex-wrap: wrap; gap: var(--space-3); justify-content: center; margin-top: var(--space-8); }
.contact__meta { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-text-faint); margin-top: var(--space-8); }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--color-border); padding-block: var(--space-8); }
.footer__inner { display: flex; flex-direction: column; gap: var(--space-4); align-items: center; text-align: center; }
.footer__name { font-family: var(--font-display); font-weight: 600; }
.footer__links { display: flex; gap: var(--space-5); }
.footer__links a { font-size: var(--text-sm); color: var(--color-text-muted); }
.footer__links a:hover { color: var(--color-primary); }
.footer__year { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-text-faint); }
@media (min-width: 700px) { .footer__inner { flex-direction: row; justify-content: space-between; } }

/* ---------- Reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 600ms ease, transform 600ms cubic-bezier(0.16, 1, 0.3, 1); }
.reveal.is-visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ---------- Print (resume-friendly) ---------- */
@media print {
  .header, .theme-toggle, .filters, .hero__grid-bg, .footer__links, .skip-link { display: none !important; }
  body { background: #fff; color: #000; font-size: 11pt; }
  .case__body { grid-template-rows: 1fr !important; }
  .case__content { overflow: visible !important; }
  .section { padding-block: var(--space-8); }
  a { color: #000; }
  .eyebrow, .timeline__period, .edu__years, .metric__value, .hero__accent { color: #0a8f78 !important; }
}