/* =========================================================================
   Ammar Kamil — portfolio
   Identity: a design document. The page sits on a diagram canvas and speaks
   UML where the notation carries something true — a class box for the
   engineer, a generalization tree for the four concerns, a live state
   machine for the order, a sequence diagram for the refund path. Prose
   stays prose.

    1. Tokens
    2. Reset & base
    3. Top bar & scroll progress
    4. Hero
    5. Shell & sections
    6. UML primitives
    7. Engineering pillars
    8. Diagrams — statechart & sequence
    9. Playground
   10. Case studies
   11. Also built / skills / contact
   12. Footer
   13. Motion
   ========================================================================= */

/* -------------------------------------------------------------------------
   1. Tokens
   ---------------------------------------------------------------------- */

:root {
  --paper:        #F2F3F0;
  --surface:      #FFFFFF;
  --surface-sunk: #E9EBE6;
  --ink:          #171A1E;
  --ink-soft:     #3C434B;
  --ink-mute:     #737A83;
  --rule:         #DCDED9;
  --rule-strong:  #B4B8B2;
  --dot:          rgba(23, 26, 30, 0.07);

  --accent:       #3949B8;
  --accent-wash:  #E6E9F8;

  --wrong:        #BE2F39;
  --wrong-wash:   #F8E4E5;
  --good:         #17805A;
  --good-wash:    #DEEEE7;

  --hue-perf:     #B0700D;
  --hue-scale:    #0C7570;
  --hue-sec:      #7B3E96;
  --hue-patt:     #A2472A;

  --shadow-card:  0 1px 2px rgba(20, 24, 30, 0.04), 0 8px 24px rgba(20, 24, 30, 0.05);
  --shadow-lift:  0 2px 4px rgba(20, 24, 30, 0.06), 0 18px 40px rgba(20, 24, 30, 0.10);

  --font-display: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --font-body:    "IBM Plex Sans", "Segoe UI", system-ui, sans-serif;
  --font-mono:    "IBM Plex Mono", ui-monospace, "Cascadia Mono", monospace;

  --step--2: 0.75rem;
  --step--1: 0.8125rem;
  --step-0:  1rem;
  --step-1:  1.125rem;
  --step-2:  1.375rem;
  --step-3:  1.75rem;
  --step-4:  clamp(2rem, 4vw, 2.5rem);
  --step-5:  clamp(2.25rem, 5.2vw, 3.75rem);

  --shell:   72rem;
  --measure: 64ch;
  --radius:  8px;
  --radius-s: 5px;

  --gap-xs: 0.5rem;
  --gap-s:  0.875rem;
  --gap-m:  1.5rem;
  --gap-l:  2.5rem;
  --gap-xl: clamp(3.5rem, 7vw, 6rem);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper:        #101317;
    --surface:      #171B20;
    --surface-sunk: #1F242A;
    --ink:          #E9EBE6;
    --ink-soft:     #B0B6BD;
    --ink-mute:     #828991;
    --rule:         #272C33;
    --rule-strong:  #414852;
    --dot:          rgba(233, 235, 230, 0.075);

    --accent:       #8A98F5;
    --accent-wash:  #212743;

    --wrong:        #F0757C;
    --wrong-wash:   #372326;
    --good:         #4FC28E;
    --good-wash:    #15302A;

    --hue-perf:     #E0A244;
    --hue-scale:    #35AFA6;
    --hue-sec:      #B983D6;
    --hue-patt:     #DE8760;

    --shadow-card:  0 1px 2px rgba(0, 0, 0, 0.30), 0 8px 24px rgba(0, 0, 0, 0.28);
    --shadow-lift:  0 2px 4px rgba(0, 0, 0, 0.35), 0 18px 40px rgba(0, 0, 0, 0.45);
  }
}

:root[data-theme="dark"] {
  --paper:        #101317;
  --surface:      #171B20;
  --surface-sunk: #1F242A;
  --ink:          #E9EBE6;
  --ink-soft:     #B0B6BD;
  --ink-mute:     #828991;
  --rule:         #272C33;
  --rule-strong:  #414852;
  --dot:          rgba(233, 235, 230, 0.075);

  --accent:       #8A98F5;
  --accent-wash:  #212743;

  --wrong:        #F0757C;
  --wrong-wash:   #372326;
  --good:         #4FC28E;
  --good-wash:    #15302A;

  --hue-perf:     #E0A244;
  --hue-scale:    #35AFA6;
  --hue-sec:      #B983D6;
  --hue-patt:     #DE8760;

  --shadow-card:  0 1px 2px rgba(0, 0, 0, 0.30), 0 8px 24px rgba(0, 0, 0, 0.28);
  --shadow-lift:  0 2px 4px rgba(0, 0, 0, 0.35), 0 18px 40px rgba(0, 0, 0, 0.45);
}

/* -------------------------------------------------------------------------
   2. Reset & base
   ---------------------------------------------------------------------- */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
  background: var(--paper);
}

body {
  margin: 0;
  background: transparent;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--step-0);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* the diagram canvas everything sits on */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image: radial-gradient(circle, var(--dot) 1px, transparent 1.2px);
  background-size: 26px 26px;
}

h1, h2, h3 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

p  { margin: 0; }
ul, ol, dl, dd { margin: 0; padding: 0; }
li { list-style: none; }

a { color: inherit; text-decoration: none; }
a:hover { color: var(--accent); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--radius-s);
}

em { font-style: normal; color: var(--accent); font-weight: 500; }

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-mute);
  line-height: 1.4;
}

.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  text-align: right;
  white-space: nowrap;
}

.table-scroll { overflow-x: auto; }

/* -------------------------------------------------------------------------
   3. Top bar & scroll progress
   ---------------------------------------------------------------------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--paper);
  background: color-mix(in srgb, var(--paper) 84%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--rule);
}

.topbar__inner {
  max-width: var(--shell);
  margin-inline: auto;
  padding: 0.7rem clamp(1.25rem, 4vw, 2.5rem);
  display: flex;
  align-items: center;
  gap: var(--gap-m);
}

.topbar__mark {
  font-family: var(--font-mono);
  font-weight: 500;
  letter-spacing: 0.08em;
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-s);
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
}

.topbar__mark:hover { color: #fff; background: var(--accent); border-color: var(--accent); }

.topbar__nav {
  display: flex;
  gap: var(--gap-m);
  margin-inline-start: auto;
  font-size: var(--step--1);
  font-family: var(--font-mono);
}

.topbar__nav a {
  position: relative;
  color: var(--ink-mute);
  padding-block: 0.2rem;
  transition: color 0.2s ease;
}

.topbar__nav a::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -0.15rem;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}

.topbar__nav a:hover,
.topbar__nav a.is-active { color: var(--accent); }
.topbar__nav a.is-active::after { transform: scaleX(1); }

@media (max-width: 46rem) {
  .topbar__nav a:not([data-nav="work"]):not([data-nav="contact"]) { display: none; }
}

.theme-toggle {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-soft);
  background: transparent;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-s);
  padding: 0.25rem 0.6rem;
  cursor: pointer;
  transition: color 0.2s ease, border-color 0.2s ease;
}

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

.progress {
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 2px;
  overflow: hidden;
}

.progress__bar {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--hue-scale), var(--accent), var(--hue-sec));
}

/* -------------------------------------------------------------------------
   4. Hero
   ---------------------------------------------------------------------- */

.hero {
  --hero-ink:      #F4F5F8;
  --hero-ink-soft: #A9B2C4;
  --hero-ink-mute: #79839B;
  --hero-line:     rgba(180, 195, 225, 0.30);

  position: relative;
  isolation: isolate;
  overflow: hidden;
  background: #0D1220;
  color: var(--hero-ink);
  border-bottom: 1px solid var(--rule);
}

.hero__bg { position: absolute; inset: 0; z-index: -1; }

.blob {
  position: absolute;
  width: min(46rem, 90vw);
  aspect-ratio: 1;
  border-radius: 50%;
  will-change: transform;
}

.blob--indigo {
  top: -34%; left: -8%;
  background: radial-gradient(circle at center, rgba(84, 101, 236, 0.55) 0%, rgba(84, 101, 236, 0) 68%);
  animation: drift-a 22s ease-in-out infinite alternate;
}

.blob--teal {
  top: 8%; right: -14%;
  background: radial-gradient(circle at center, rgba(23, 158, 148, 0.40) 0%, rgba(23, 158, 148, 0) 68%);
  animation: drift-b 27s ease-in-out infinite alternate;
}

.blob--plum {
  bottom: -42%; left: 30%;
  background: radial-gradient(circle at center, rgba(150, 76, 190, 0.36) 0%, rgba(150, 76, 190, 0) 68%);
  animation: drift-c 31s ease-in-out infinite alternate;
}

@keyframes drift-a {
  from { transform: translate3d(0, 0, 0) scale(1); }
  to   { transform: translate3d(6%, 9%, 0) scale(1.14); }
}
@keyframes drift-b {
  from { transform: translate3d(0, 0, 0) scale(1.08); }
  to   { transform: translate3d(-9%, 12%, 0) scale(0.94); }
}
@keyframes drift-c {
  from { transform: translate3d(0, 0, 0) scale(0.96); }
  to   { transform: translate3d(8%, -10%, 0) scale(1.16); }
}

.hero__grid {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle, var(--hero-line) 1px, transparent 1.2px);
  background-size: 26px 26px;
  -webkit-mask-image: linear-gradient(to bottom, rgba(0,0,0,0.85), transparent 92%);
  mask-image: linear-gradient(to bottom, rgba(0,0,0,0.85), transparent 92%);
}

.hero__inner {
  max-width: var(--shell);
  margin-inline: auto;
  padding: clamp(3.5rem, 8vw, 6.5rem) clamp(1.25rem, 4vw, 2.5rem) clamp(3rem, 6vw, 5rem);
  display: grid;
  gap: var(--gap-l);
  align-items: center;
}

@media (min-width: 64rem) {
  .hero__inner { grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr); }
}

.hero__copy { display: flex; flex-direction: column; gap: var(--gap-m); min-width: 0; }

.hero__eyebrow {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--hero-ink-mute);
}

.hero__thesis { font-size: var(--step-5); max-width: 15ch; color: var(--hero-ink); }

.hero__accent {
  background: linear-gradient(100deg, #7C8CF8 0%, #4FC7BC 45%, #C98BE6 100%);
  background-size: 220% 100%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: hue-slide 9s ease-in-out infinite alternate;
}

@keyframes hue-slide {
  from { background-position: 0% 50%; }
  to   { background-position: 100% 50%; }
}

.hero__lede { max-width: var(--measure); font-size: var(--step-1); color: var(--hero-ink-soft); }

.facts {
  display: flex;
  flex-wrap: wrap;
  margin-block: var(--gap-xs);
  border-block: 1px solid var(--hero-line);
}

.facts li {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  padding: var(--gap-s) var(--gap-l) var(--gap-s) 0;
  margin-inline-end: var(--gap-l);
  border-inline-end: 1px solid var(--hero-line);
}

.facts li:last-child { border-inline-end: 0; margin-inline-end: 0; padding-inline-end: 0; }

.facts__value {
  font-family: var(--font-display);
  font-size: var(--step-4);
  font-weight: 700;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--hero-ink);
}

.facts__label { font-family: var(--font-mono); font-size: var(--step--1); color: var(--hero-ink-mute); }

.hero__actions { display: flex; flex-wrap: wrap; gap: var(--gap-xs); }

.cta {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  padding: 0.55rem 1.1rem;
  border-radius: 999px;
  border: 1px solid transparent;
  background: var(--hero-ink);
  color: #0D1220;
  transition: transform 0.2s ease, background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.cta:hover { transform: translateY(-2px); background: #fff; color: #0D1220; }

.cta--ghost {
  background: transparent;
  color: var(--hero-ink-soft);
  border-color: rgba(180, 195, 225, 0.28);
}

.cta--ghost:hover {
  background: rgba(180, 195, 225, 0.10);
  color: var(--hero-ink);
  border-color: rgba(180, 195, 225, 0.55);
}

.hero__class { min-width: 0; }

/* -------------------------------------------------------------------------
   5. Shell & sections
   ---------------------------------------------------------------------- */

.shell {
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 4vw, 2.5rem);
}

.section {
  display: grid;
  gap: var(--gap-m);
  padding-block: var(--gap-xl);
  border-top: 1px solid var(--rule);
}

.shell > .section:first-child { border-top: 0; }

@media (min-width: 56rem) {
  .section { grid-template-columns: 11rem 1fr; column-gap: var(--gap-l); }
  .section__label { position: sticky; top: 5rem; align-self: start; }
}

.section__label { display: flex; flex-direction: column; gap: var(--gap-xs); }

.section__hint { font-size: var(--step--1); color: var(--ink-mute); max-width: 26ch; }

.section__body {
  display: flex;
  flex-direction: column;
  gap: var(--gap-m);
  min-width: 0;
}

.section__title { font-size: var(--step-4); max-width: 20ch; }

.prose { max-width: var(--measure); color: var(--ink-soft); }
.prose--lead { font-size: var(--step-1); color: var(--ink); }

/* -------------------------------------------------------------------------
   6. UML primitives
   ---------------------------------------------------------------------- */

.uml-box {
  background: var(--surface);
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius-s);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  font-family: var(--font-mono);
  font-size: var(--step--1);
}

.uml-box__head {
  display: flex;
  flex-direction: column;
  gap: 0.05rem;
  align-items: center;
  text-align: center;
  padding: var(--gap-s);
  background: var(--surface-sunk);
  border-bottom: 1px solid var(--rule-strong);
}

.uml-box__stereotype {
  font-size: var(--step--2);
  letter-spacing: 0.08em;
  color: var(--ink-mute);
}

.uml-box__name {
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.uml-box__members {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: var(--gap-s);
  color: var(--ink-soft);
  line-height: 1.5;
}

.uml-box__members--ops { border-top: 1px solid var(--rule); }

.uml-box__members li { display: flex; gap: 0.4rem; flex-wrap: wrap; }

.uml-vis { color: var(--accent); font-weight: 600; }
.uml-type { color: var(--ink-mute); }

/* the engineer box lives on the dark hero band */
.uml-box--hero {
  background: rgba(18, 24, 40, 0.72);
  border-color: rgba(180, 195, 225, 0.30);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.40);
  backdrop-filter: blur(6px);
}

.uml-box--hero .uml-box__head {
  background: rgba(180, 195, 225, 0.08);
  border-bottom-color: rgba(180, 195, 225, 0.28);
}

.uml-box--hero .uml-box__stereotype { color: var(--hero-ink-mute); }
.uml-box--hero .uml-box__name       { color: var(--hero-ink); }
.uml-box--hero .uml-box__members    { color: var(--hero-ink-soft); }
.uml-box--hero .uml-box__members--ops { border-top-color: rgba(180, 195, 225, 0.22); }
.uml-box--hero .uml-vis  { color: #8FA5FF; }
.uml-box--hero .uml-type { color: var(--hero-ink-mute); }

/* an abstract class carries an italic name in UML */
.uml-box--abstract { border-color: color-mix(in srgb, var(--accent) 35%, var(--rule-strong)); }
.uml-box--abstract .uml-box__name { font-style: italic; }

/* package notation --------------------------------------------------- */

.uml-package {
  position: relative;
  margin-top: 1.75rem;
  padding: var(--gap-m);
  background: var(--surface);
  border: 1px solid var(--rule-strong);
  border-radius: 0 var(--radius) var(--radius) var(--radius);
  box-shadow: var(--shadow-card);
}

.uml-package__tab {
  position: absolute;
  top: -1.75rem;
  left: -1px;
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: 0.06em;
  color: var(--ink-mute);
  background: var(--surface-sunk);
  border: 1px solid var(--rule-strong);
  border-bottom: 0;
  border-radius: var(--radius-s) var(--radius-s) 0 0;
  padding: 0.3rem 0.9rem;
}

/* final node ---------------------------------------------------------- */

.uml-final {
  display: flex;
  align-items: center;
  gap: var(--gap-xs);
  padding-top: var(--gap-s);
}

.uml-final__node {
  width: 1.1rem;
  height: 1.1rem;
  border-radius: 50%;
  border: 1.5px solid var(--ink-mute);
  position: relative;
  flex: none;
}

.uml-final__node::after {
  content: "";
  position: absolute;
  inset: 3px;
  border-radius: 50%;
  background: var(--ink-mute);
}

.uml-final__label {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
}

/* -------------------------------------------------------------------------
   7. Engineering pillars — a generalization tree
   ---------------------------------------------------------------------- */

.uml-tree { position: relative; }

.uml-tree__parent { display: flex; justify-content: center; position: relative; z-index: 1; }
.uml-tree__parent .uml-box { width: min(24rem, 100%); }

/* below the two-column breakpoint the wires are replaced by one trunk */
.uml-tree__parent::after {
  content: "";
  width: 1px;
  height: var(--gap-m);
  background: var(--rule-strong);
  position: absolute;
  bottom: calc(var(--gap-m) * -1);
  left: 50%;
}

.uml-tree__wires {
  display: none;
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  pointer-events: none;
  z-index: 0;
}

.uml-wire {
  fill: none;
  stroke: color-mix(in srgb, var(--accent) 45%, var(--rule-strong));
  stroke-width: 1.5;
  stroke-linecap: square;
  transition: stroke-dashoffset 0.9s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.uml-arrowhead {
  fill: var(--surface);
  stroke: color-mix(in srgb, var(--accent) 45%, var(--rule-strong));
  stroke-width: 1.5;
  stroke-linejoin: miter;
  opacity: 0;
  transition: opacity 0.5s ease 0.45s;
}

.uml-tree__wires.is-drawn .uml-arrowhead { opacity: 1; }

.pillars {
  display: grid;
  gap: var(--gap-s);
  position: relative;
  z-index: 1;
  margin-top: var(--gap-l);
}

@media (min-width: 46rem) {
  .uml-tree { padding-inline: 1.6rem; }
  .uml-tree__wires { display: block; }
  .uml-tree__parent::after { display: none; }
  .pillars { grid-template-columns: repeat(2, 1fr); gap: var(--gap-m); margin-top: 3.25rem; }
}

.pillar {
  --hue: var(--accent);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--gap-xs);
  padding: var(--gap-m);
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.pillar::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--hue);
  transform: scaleX(0.14);
  transform-origin: left;
  transition: transform 0.35s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.pillar:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lift);
  border-color: color-mix(in srgb, var(--hue) 40%, var(--rule));
}

.pillar:hover::before { transform: scaleX(1); }

.pillar[data-hue="perf"]  { --hue: var(--hue-perf); }
.pillar[data-hue="scale"] { --hue: var(--hue-scale); }
.pillar[data-hue="sec"]   { --hue: var(--hue-sec); }
.pillar[data-hue="patt"]  { --hue: var(--hue-patt); }

.pillar__eyebrow {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--hue);
}

.pillar__title { font-size: var(--step-2); }

.pillar__list { display: flex; flex-direction: column; gap: var(--gap-xs); margin-top: var(--gap-xs); }

.pillar__list li {
  position: relative;
  padding-inline-start: 1.1rem;
  font-size: var(--step--1);
  color: var(--ink-soft);
  line-height: 1.55;
}

.pillar__list li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.6em;
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--hue);
  opacity: 0.65;
}

/* -------------------------------------------------------------------------
   8. Diagrams — statechart & sequence
   ---------------------------------------------------------------------- */

.diagram {
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--gap-xs);
  padding: var(--gap-m);
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
}

.diagram__caption {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--gap-xs);
}

.diagram__legend {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-mono);
  font-size: var(--step--2);
  color: var(--ink-mute);
}

.dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  display: inline-block;
  margin-inline-start: 0.55rem;
}

.dot--active { background: var(--accent); }
.dot--past   { background: color-mix(in srgb, var(--accent) 40%, var(--rule-strong)); }
.dot--next   { background: transparent; border: 1.5px dashed var(--accent); }

.diagram__scroll { overflow-x: auto; padding-block: var(--gap-xs); }

.statechart, .sequence { display: block; width: 100%; }
.statechart { min-width: 620px; }
.sequence   { min-width: 600px; }

/* statechart ----------------------------------------------------------- */

.sc-edges path {
  fill: none;
  stroke: var(--rule-strong);
  stroke-width: 1.5;
}

.sc-arrowhead { fill: var(--rule-strong); }

.sc-node { fill: var(--ink-soft); }
.sc-node--final-ring { fill: none; stroke: var(--ink-soft); stroke-width: 1.5; }

.sc-state rect {
  fill: var(--surface-sunk);
  stroke: var(--rule-strong);
  stroke-width: 1.5;
  transition: fill 0.3s ease, stroke 0.3s ease;
}

.sc-state text {
  font-family: var(--font-mono);
  font-size: 12px;
  fill: var(--ink-mute);
  text-anchor: middle;
  transition: fill 0.3s ease;
}

.sc-state.is-past rect {
  fill: var(--accent-wash);
  stroke: color-mix(in srgb, var(--accent) 45%, var(--rule-strong));
}
.sc-state.is-past text { fill: var(--ink-soft); }

.sc-state.is-active rect {
  fill: var(--accent-wash);
  stroke: var(--accent);
  stroke-width: 2.25;
}
.sc-state.is-active text { fill: var(--accent); font-weight: 600; }

.sc-state.is-next rect {
  fill: none;
  stroke: var(--accent);
  stroke-dasharray: 5 4;
  opacity: 0.75;
}
.sc-state.is-next text { fill: var(--accent); opacity: 0.85; }

/* sequence ------------------------------------------------------------- */

.seq-actor rect {
  fill: var(--surface-sunk);
  stroke: var(--rule-strong);
  stroke-width: 1.5;
}

.seq-actor text {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  fill: var(--ink);
  text-anchor: middle;
}

.seq-lifeline path {
  fill: none;
  stroke: var(--rule-strong);
  stroke-width: 1.25;
  stroke-dasharray: 3 5;
}

.seq-message path {
  fill: none;
  stroke: var(--accent);
  stroke-width: 1.5;
}

.seq-message text {
  font-family: var(--font-mono);
  font-size: 11px;
  fill: var(--ink-soft);
}

.seq-message--return path { stroke: var(--good); stroke-dasharray: 6 4; }
.seq-message--return text { fill: var(--good); }

.seq-arrowhead { fill: var(--accent); }
.seq-arrowhead--soft { fill: var(--good); }

/* -------------------------------------------------------------------------
   9. Playground
   ---------------------------------------------------------------------- */

.pg { display: grid; gap: var(--gap-m); }

@media (min-width: 60rem) {
  .pg { grid-template-columns: 1fr 1fr; align-items: start; }
  .pg__result { position: sticky; top: 5rem; }
}

.panel {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: var(--gap-m);
  display: flex;
  flex-direction: column;
  gap: var(--gap-m);
  min-width: 0;
}

.panel__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--gap-s);
  padding-bottom: var(--gap-s);
  border-bottom: 1px solid var(--rule);
}

.panel__title { font-size: var(--step-2); }

.badge {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--accent);
  background: var(--accent-wash);
  border-radius: 999px;
  padding: 0.1rem 0.7rem;
  white-space: nowrap;
}

.panel__actions { display: flex; flex-wrap: wrap; gap: var(--gap-xs); }

.btn {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--surface);
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 999px;
  padding: 0.45rem 1rem;
  cursor: pointer;
  transition: transform 0.2s ease, background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

.btn:hover { transform: translateY(-2px); background: var(--accent); border-color: var(--accent); color: #fff; }

.btn--quiet { color: var(--ink-soft); background: transparent; border-color: var(--rule-strong); }
.btn--quiet:hover { color: var(--accent); background: var(--accent-wash); border-color: var(--accent); }

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

.lines__empty { font-size: var(--step--1); color: var(--ink-mute); }

.line {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--gap-s);
  padding: var(--gap-s) var(--gap-xs);
  margin-inline: calc(var(--gap-xs) * -1);
  border-radius: var(--radius-s);
  border-bottom: 1px dotted var(--rule-strong);
  transition: background-color 0.2s ease;
}

.line:hover { background: var(--surface-sunk); }
.line.is-returning { background: var(--accent-wash); }

.line__info { display: flex; flex-direction: column; gap: 0.1rem; min-width: 0; }
.line__name { font-weight: 500; }

.line__meta {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-variant-numeric: tabular-nums;
  color: var(--ink-mute);
}

.stepper {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  padding: 0.12rem;
  background: var(--paper);
}

.stepper__btn {
  font-family: var(--font-mono);
  font-size: var(--step-0);
  line-height: 1;
  width: 1.75rem;
  height: 1.75rem;
  color: var(--ink);
  background: transparent;
  border: 0;
  border-radius: 50%;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.stepper__btn:hover:not(:disabled) { background: var(--accent); color: #fff; }
.stepper__btn:disabled { color: var(--ink-mute); opacity: 0.35; cursor: default; }

.stepper__value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  min-width: 2.6rem;
  text-align: center;
  font-size: var(--step--1);
  color: var(--ink-soft);
}

.promo { display: flex; flex-direction: column; gap: var(--gap-xs); }

.seg {
  display: inline-flex;
  align-self: start;
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  overflow: hidden;
}

.seg__btn {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-soft);
  background: transparent;
  border: 0;
  border-inline-end: 1px solid var(--rule-strong);
  padding: 0.4rem 0.9rem;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.seg__btn:last-child { border-inline-end: 0; }
.seg__btn:hover { color: var(--accent); background: var(--accent-wash); }
.seg__btn.is-active { background: var(--ink); color: var(--surface); }

.promo__note { font-size: var(--step--1); color: var(--ink-mute); max-width: 46ch; }

.ledger { width: 100%; border-collapse: collapse; font-size: var(--step--1); }

.ledger caption { text-align: left; padding-bottom: var(--gap-xs); }

.ledger th,
.ledger td {
  padding: 0.42rem 0;
  text-align: left;
  font-weight: 400;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--rule);
}

.ledger thead th {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-mute);
}

.ledger td.num, .ledger th.num { padding-inline-start: var(--gap-s); }

.ledger__total th,
.ledger__total td {
  border-bottom: 0;
  border-top: 2px solid var(--rule-strong);
  padding-top: 0.55rem;
  color: var(--ink);
  font-weight: 500;
}

.ledger--breakdown tbody tr:last-child th,
.ledger--breakdown tbody tr:last-child td { border-bottom: 0; }

.ledger--breakdown .is-share { color: var(--wrong); }

.ledger__empty { color: var(--ink-mute); font-style: italic; }

.verdict { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap-s); }

.verdict__col {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: var(--gap-s);
  border-radius: var(--radius-s);
  border: 1px solid transparent;
}

.verdict__col--wrong { background: var(--wrong-wash); border-color: color-mix(in srgb, var(--wrong) 22%, transparent); }
.verdict__col--right { background: var(--good-wash);  border-color: color-mix(in srgb, var(--good) 22%, transparent); }

.verdict__col--wrong .eyebrow { color: color-mix(in srgb, var(--wrong) 75%, var(--ink-mute)); }
.verdict__col--right .eyebrow { color: color-mix(in srgb, var(--good) 75%, var(--ink-mute)); }

.figure {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--step-3);
  font-weight: 500;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--good);
}

.figure--wrong { color: var(--wrong); text-decoration: line-through; text-decoration-thickness: 1px; }

.figure__note { font-size: var(--step--1); color: var(--ink-mute); line-height: 1.4; }

.delta {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--wrong);
  background: var(--wrong-wash);
  border-inline-start: 3px solid var(--wrong);
  border-radius: 0 var(--radius-s) var(--radius-s) 0;
  padding: var(--gap-xs) var(--gap-s);
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.delta.is-clean { color: var(--good); background: var(--good-wash); border-inline-start-color: var(--good); }
.delta.is-pulsing { animation: pulse 0.45s ease; }

@keyframes pulse {
  0%   { transform: scale(1); }
  35%  { transform: scale(1.02); }
  100% { transform: scale(1); }
}

.invariant {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-mute);
  padding-top: var(--gap-xs);
  border-top: 1px solid var(--rule);
  transition: color 0.3s ease;
}

.invariant.is-balanced { color: var(--good); }

.note { border-top: 1px solid var(--rule); padding-top: var(--gap-s); max-width: var(--measure); }

.note summary {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-soft);
  cursor: pointer;
}

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

.note__body {
  display: flex;
  flex-direction: column;
  gap: var(--gap-s);
  padding-top: var(--gap-s);
  color: var(--ink-soft);
  font-size: var(--step--1);
}

/* -------------------------------------------------------------------------
   10. Case studies
   ---------------------------------------------------------------------- */

.case {
  display: flex;
  flex-direction: column;
  gap: var(--gap-s);
  padding-block: var(--gap-m);
  border-top: 1px solid var(--rule);
}

.case__head { display: flex; flex-direction: column; gap: var(--gap-xs); }

.case__title { font-size: var(--step-3); max-width: 22ch; transition: color 0.25s ease; }
.case:hover .case__title { color: var(--accent); }

.case__org {
  display: flex;
  flex-wrap: wrap;
  gap: var(--gap-s);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
}

.case__years { color: var(--ink-mute); }

.case__context { max-width: var(--measure); color: var(--ink-soft); }

.case__body { display: flex; flex-direction: column; gap: var(--gap-s); }

.case__row { display: grid; gap: 0.2rem; }

@media (min-width: 44rem) {
  .case__row { grid-template-columns: 8.5rem 1fr; column-gap: var(--gap-m); }
}

.case__row dt {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-mute);
  padding-top: 0.3rem;
}

.case__row dd { max-width: var(--measure); color: var(--ink-soft); }

.tags { display: flex; flex-wrap: wrap; gap: var(--gap-xs); }

.tags li {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  color: var(--ink-mute);
  background: var(--surface-sunk);
  border-radius: 999px;
  padding: 0.18rem 0.6rem;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.tags li:hover { color: var(--accent); background: var(--accent-wash); }

/* -------------------------------------------------------------------------
   11. Also built / skills / contact
   ---------------------------------------------------------------------- */

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

.also li {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: var(--gap-s);
  margin-inline: calc(var(--gap-s) * -1);
  border-radius: var(--radius-s);
  border-bottom: 1px solid var(--rule);
  transition: background-color 0.2s ease;
}

.also li:hover { background: var(--surface); }
.also li:last-child { border-bottom: 0; }
.also h3 { font-size: var(--step-1); }
.also p { max-width: var(--measure); color: var(--ink-soft); font-size: var(--step--1); }

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

.skills__row {
  display: grid;
  gap: 0.1rem;
  padding-block: var(--gap-s);
  border-bottom: 1px solid var(--rule);
}

.skills__row:first-child { padding-top: 0; }
.skills__row:last-child { border-bottom: 0; padding-bottom: 0; }

@media (min-width: 44rem) {
  .skills__row { grid-template-columns: 10rem 1fr; column-gap: var(--gap-m); }
}

.skills__row dt {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-mute);
}

.skills__row dd { color: var(--ink-soft); }

.channels { display: grid; gap: var(--gap-xs); }

@media (min-width: 40rem) {
  .channels { grid-template-columns: repeat(2, 1fr); }
}

.channel {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  padding: var(--gap-s) var(--gap-m);
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.channel:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
  box-shadow: var(--shadow-lift);
  color: inherit;
}

.channel--static { box-shadow: none; background: transparent; }
.channel--static:hover { transform: none; border-color: var(--rule); box-shadow: none; }

.channel__key {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-mute);
}

.channel__value {
  font-family: var(--font-mono);
  font-size: var(--step-0);
  color: var(--ink);
  word-break: break-word;
}

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

/* -------------------------------------------------------------------------
   12. Footer
   ---------------------------------------------------------------------- */

.footer { border-top: 1px solid var(--rule); background: var(--surface); }

.footer__inner {
  max-width: var(--shell);
  margin-inline: auto;
  padding: var(--gap-m) clamp(1.25rem, 4vw, 2.5rem);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--gap-m);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-mute);
}

.footer__identity { display: flex; flex-direction: column; gap: 0.1rem; }
.footer__name { color: var(--ink); font-weight: 500; }
.footer__links { display: flex; flex-wrap: wrap; gap: var(--gap-m); }

/* -------------------------------------------------------------------------
   13. Motion
   ---------------------------------------------------------------------- */

/* Reveal uses the independent `translate` property, not `transform`, so it
   never cancels the hover lifts declared on the cards above. */
.reveal {
  opacity: 0;
  translate: 0 1.25rem;
  transition: opacity 0.6s cubic-bezier(0.2, 0.7, 0.3, 1),
              translate 0.6s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.reveal.is-visible { opacity: 1; translate: none; }

[data-stagger] {
  opacity: 0;
  translate: 0 1rem;
  animation: rise 0.75s cubic-bezier(0.2, 0.7, 0.3, 1) forwards;
}

[data-stagger="1"] { animation-delay: 0.05s; }
[data-stagger="2"] { animation-delay: 0.15s; }
[data-stagger="3"] { animation-delay: 0.28s; }
[data-stagger="4"] { animation-delay: 0.40s; }
[data-stagger="5"] { animation-delay: 0.52s; }

@keyframes rise {
  to { opacity: 1; translate: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, [data-stagger] {
    opacity: 1;
    translate: none;
    transform: none;
    transition: none;
    animation: none;
  }
  .blob, .hero__accent { animation: none; }
  .hero__accent { background-position: 30% 50%; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}