:root {
  --bg: #161c1a;
  --surface: #1f2725;
  --surface-2: #28322f;
  --deep: #101513;
  --ink: #e3e2da;
  --muted: #a3a9a1;
  --accent: #9fc7b8;
  --accent-ink: #161c1a;
  --string: #d9c99c;
  --removed: #e0a39a;
  --added: #9fc7b8;

  /* Five sizes: small, body, lead, head, display */
  --step-small: 0.875rem;
  --step-body: clamp(1.0625rem, 1rem + 0.25vw, 1.1875rem);
  --step-lead: clamp(1.375rem, 1.15rem + 0.7vw, 1.75rem);
  --step-head: clamp(2.25rem, 1.4rem + 2.4vw, 3.5rem);
  --step-display: clamp(2.75rem, 1.6rem + 3.6vw, 5rem);

  --m: clamp(20px, 2.8vw, 40px);
  --gap-section: clamp(120px, 13vw, 200px);
  --radius: 4px;

  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-expo: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-soft: cubic-bezier(0.33, 1, 0.68, 1);
  --t-press: 140ms;
  --t-hover: 180ms;
  --t-ui: 240ms;
  --t-reveal: 800ms;
}

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

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  overflow-x: clip;
  background: var(--bg);
  color: var(--ink);
  font-family: "Albert Sans", system-ui, sans-serif;
  font-size: var(--step-body);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
}

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

::selection {
  background: var(--accent);
  color: var(--accent-ink);
}

h1,
h2,
h3 {
  margin: 0;
  font-weight: 600;
  letter-spacing: -0.035em;
  line-height: 1;
}

p {
  margin: 0;
}

/* Literal code is the only monospace on the site */
code,
pre,
textarea.code-input {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.875em;
}

pre {
  font-size: var(--step-small);
}

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

/* Buttons and links: one square shape on the whole site */

.button {
  display: inline-flex;
  align-items: center;
  padding: 0.85em 1.4em;
  border: 0;
  border-radius: var(--radius);
  background: var(--accent);
  color: var(--accent-ink);
  font: 500 var(--step-body) / 1 "Albert Sans", system-ui, sans-serif;
  text-decoration: none;
  cursor: pointer;
  transition:
    transform var(--t-press) var(--ease-out),
    background-color var(--t-hover) var(--ease-out);
}

.button:hover {
  background: #b6d8cb;
}

.button:active {
  transform: scale(0.97);
}

.button--quiet {
  background: var(--surface-2);
  color: var(--ink);
}

.button--quiet:hover {
  background: #33403c;
}

.link {
  text-decoration: underline;
  text-decoration-color: transparent;
  text-underline-offset: 0.25em;
  transition: text-decoration-color var(--t-ui) var(--ease-out);
}

.link:hover,
.link:focus-visible {
  text-decoration-color: currentColor;
}

/* Interface fragments: the product's own conventions apply inside */

[data-ui] {
  font-size: var(--step-small);
  line-height: 1.6;
}

.code {
  margin: 0;
  padding: 18px 20px;
  overflow-x: auto;
  white-space: pre;
  line-height: 1.65;
}

.code .c {
  color: var(--muted);
}

.code .s {
  color: var(--string);
}

.code .k {
  color: var(--accent);
}

.code .ln {
  display: inline-block;
  width: 2em;
  margin-right: 1em;
  color: #79807a;
  text-align: right;
  user-select: none;
}

.del {
  color: var(--removed);
}

.add,
.ok {
  color: var(--added);
}

.fail {
  color: var(--removed);
}

.code .hl {
  background: rgba(224, 163, 154, 0.14);
}

.panel-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 44px;
  padding: 6px 12px 6px 20px;
  background: var(--deep);
  color: var(--muted);
}

.panel-bar code {
  font-size: 1em;
}

.ui-button {
  padding: 6px 12px;
  border: 1px solid #3a4743;
  border-radius: 3px;
  background: var(--surface-2);
  color: var(--ink);
  font: inherit;
  cursor: pointer;
  transition:
    background-color var(--t-hover) var(--ease-out),
    border-color var(--t-hover) var(--ease-out),
    transform var(--t-press) var(--ease-out);
}

.ui-button:hover {
  background: #33403c;
}

.ui-button:active {
  transform: scale(0.96);
}

.ui-button--accept,
.ui-button[aria-pressed="true"] {
  border-color: var(--accent);
  color: var(--accent);
}

.field {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid #3a4743;
  border-radius: 3px;
  background: var(--bg);
  color: var(--ink);
  font: inherit;
  transition: border-color var(--t-hover) var(--ease-out);
}

.field:hover,
.field:focus {
  border-color: var(--accent);
  outline: none;
}

/* Page frame */

.topbar {
  position: absolute;
  inset: 0 0 auto;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--m);
}

.wordmark {
  font-weight: 600;
  font-size: var(--step-lead);
  letter-spacing: -0.03em;
  text-decoration: none;
}

.topbar nav {
  display: flex;
  gap: 28px;
}

/* Hero: the snapshot of this page */

.hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  min-height: max(100svh, 720px);
}

.hero > * {
  min-width: 0;
}

.hero__copy {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: var(--m);
  padding-bottom: clamp(48px, 8vh, 96px);
}

.hero h1 {
  font-size: var(--step-head);
}

.line {
  display: block;
  overflow: clip;
  padding-bottom: 0.08em;
}

.line > span {
  display: block;
}

.hero__sentence {
  max-width: 44ch;
  margin-top: 32px;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 24px;
  margin-top: 36px;
}

.hero__stage {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 104px var(--m) var(--m);
  background: var(--surface);
}

.page-snapshot {
  width: min(580px, 100%);
  background: var(--deep);
  border-radius: 6px;
  overflow: hidden;
}

.page-snapshot .code {
  background: var(--bg);
}

.page-snapshot__field {
  display: grid;
  gap: 6px;
  padding: 16px 20px 4px;
}

.page-snapshot__field label {
  color: var(--muted);
}

.page-snapshot__result {
  margin: 0;
  padding: 14px 20px 18px;
  white-space: pre-wrap;
  min-height: 3.4em;
}

.page-snapshot__result.is-failed {
  background: #261c1a;
}

/* Showcase: any value, readable Scala */

.showcase {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin-top: var(--gap-section);
}

.showcase > * {
  min-width: 0;
}

.showcase__in,
.showcase__out {
  min-height: 90svh;
  padding: 88px var(--m) calc(var(--step-display) + 96px);
}

.showcase__in {
  background: var(--deep);
}

.showcase__in label {
  display: block;
  margin-bottom: 16px;
}

.showcase textarea {
  display: block;
  width: min(36ch, 100%);
  min-height: 9em;
  padding: 14px 16px;
  font-size: var(--step-lead);
  line-height: 1.45;
  resize: vertical;
}

.presets {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.showcase__out {
  background: var(--ink);
  color: var(--bg);
}

.showcase__out [data-ui] {
  width: min(680px, 100%);
  background: var(--bg);
  border-radius: 6px;
  overflow: hidden;
  color: var(--ink);
}

.showcase__out .code {
  font-size: 13px;
}

.showcase__out .note {
  max-width: 42ch;
  margin-top: 28px;
}

.split-heading {
  font-size: var(--step-display);
}

.split-heading span {
  position: absolute;
  bottom: 40px;
}

.split-heading span:first-child {
  left: var(--m);
}

.split-heading span:last-child {
  right: var(--m);
  color: var(--bg);
}

/* How it works: one pinned fragment, three statements */

.steps {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--m);
  margin: var(--gap-section) var(--m) 0;
}

.steps__text {
  grid-column: 1 / span 5;
}

.steps h2 {
  font-size: var(--step-lead);
  letter-spacing: -0.02em;
}

.step {
  min-height: 80vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.step:first-of-type {
  min-height: 64vh;
}

.step h3 {
  max-width: 16ch;
  font-size: var(--step-head);
  line-height: 1.05;
  color: var(--muted);
  transition: color var(--t-ui) var(--ease-out);
}

.step.is-active h3 {
  color: var(--ink);
}

.step p {
  max-width: 40ch;
  margin-top: 20px;
}

.stage {
  grid-column: 7 / span 6;
  position: sticky;
  top: 12vh;
  align-self: start;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 76vh;
  padding: var(--m);
  background: var(--surface);
}

.stage [data-ui] {
  width: min(600px, 100%);
  background: var(--bg);
  border-radius: 6px;
  overflow: hidden;
}

.stage__state {
  display: none;
}

.stage[data-state="test"] .stage__state--test,
.stage[data-state="record"] .stage__state--record,
.stage[data-state="fail"] .stage__state--fail {
  display: block;
}

/* Frameworks, platforms and modes */

.catalog {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--m);
  margin: var(--gap-section) var(--m) 0;
}

.catalog__list {
  grid-column: 3 / span 8;
}

.catalog__groups {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 calc(var(--m) * 2);
}

.catalog h2 {
  margin-bottom: 40px;
  font-size: var(--step-head);
}

.catalog ul {
  margin: 0 0 40px;
  padding: 0;
  list-style: none;
}

.catalog .group {
  margin-bottom: 4px;
  color: var(--muted);
}

.catalog li {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 7px 0;
}

.catalog li > span:first-child {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.catalog li > span:first-child::before {
  content: "";
  flex: none;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--dot, var(--accent));
}

.catalog li > span:last-child {
  color: var(--muted);
  font-size: var(--step-small);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.catalog li a {
  text-decoration: none;
  transition: color var(--t-hover) var(--ease-out);
}

.catalog li a:hover {
  color: var(--accent);
}

figcaption {
  margin-top: 12px;
  color: var(--muted);
  font-size: var(--step-small);
}

/* Why: one statement with interface words, and its picture */

.why {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--m);
  margin: var(--gap-section) var(--m) 0;
  align-items: end;
}

.why__text {
  grid-column: 1 / span 6;
}

.why__ci {
  grid-column: 8 / span 5;
  align-self: center;
  border-radius: 6px;
  overflow: hidden;
  background: var(--bg);
}

.why__ci .code {
  background: var(--deep);
}

.why__statement {
  max-width: 24ch;
  font-size: clamp(1.5rem, 1rem + 1.6vw, 2.25rem);
  line-height: 1.25;
  font-weight: 500;
  letter-spacing: -0.02em;
}

.why__follow {
  max-width: 40ch;
  margin-top: 56px;
}

.why__follow p {
  margin-bottom: 28px;
}

/* Close: the action tile */

.close {
  display: grid;
  grid-template-columns: 2fr 8fr 2fr;
  gap: 12px;
  margin-top: var(--gap-section);
}

.close > * {
  min-height: 380px;
  border-radius: var(--radius);
  overflow: clip;
}

.close__tile {
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 40px clamp(24px, 4vw, 56px);
  background: var(--accent);
  color: var(--accent-ink);
}

.close__tile h2 {
  font-size: var(--step-head);
}

.close__tile pre {
  margin: 24px 0 0;
  padding: 12px 14px;
  border-radius: 3px;
  background: rgba(22, 28, 26, 0.1);
  white-space: pre-wrap;
  word-break: break-word;
}

.close__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.close__tile .button {
  background: var(--bg);
  color: var(--ink);
}

.close__tile .button:hover {
  background: var(--surface-2);
}

.close__tile .button--quiet {
  background: transparent;
  color: var(--accent-ink);
  border: 2px solid var(--accent-ink);
}

.close__tile .button--quiet:hover {
  background: rgba(22, 28, 26, 0.08);
}

.close__field {
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
  background: var(--surface);
}

.close__field--left {
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--surface-2);
}

/* Footer: one quiet line */

.footer {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: baseline;
  gap: 24px;
  margin-top: 30svh;
  padding: 0 var(--m) 24px;
  color: var(--muted);
}

.footer nav {
  display: flex;
  gap: 24px;
}

.footer nav a {
  color: var(--ink);
}

.footer p:last-child {
  text-align: right;
}

/* Motion: content stays visible without script and with reduced motion */

@media (prefers-reduced-motion: no-preference) {
  html.js .line > span {
    transform: translateY(105%);
    animation: rise 900ms var(--ease-expo) forwards;
    animation-delay: calc(150ms + var(--i, 0) * 110ms);
  }

  html.js .hero__sentence,
  html.js .hero__actions {
    opacity: 0;
    animation: fade-up var(--t-reveal) var(--ease-expo) 520ms forwards;
  }

  html.js .hero__stage [data-ui] {
    opacity: 0;
    animation: fade-up 1000ms var(--ease-expo) 300ms forwards;
  }

  html.js [data-reveal] {
    opacity: 0;
    transform: translateY(24px);
    transition:
      opacity var(--t-reveal) var(--ease-expo),
      transform var(--t-reveal) var(--ease-expo);
    transition-delay: calc(var(--i, 0) * 70ms);
  }

  html.js [data-reveal].is-in {
    opacity: 1;
    transform: none;
  }

  html.js .stage__state {
    animation: settle 500ms var(--ease-out);
  }

}

@keyframes rise {
  to {
    transform: none;
  }
}

@keyframes fade-up {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes settle {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
}

@keyframes drift {
  from {
    transform: scale(1.08) translateX(-2%);
  }
  to {
    transform: scale(1.14) translateX(2%);
  }
}

/* Tablet and phone: stacked compositions */

@media (max-width: 960px) {
  .hero {
    grid-template-columns: 1fr;
  }

  .hero__stage {
    min-height: 58svh;
    padding: 40px var(--m);
  }

  .hero__copy {
    min-height: min(78svh, 640px);
    padding-top: 120px;
  }

  .showcase {
    grid-template-columns: 1fr;
  }

  .showcase__in,
  .showcase__out {
    min-height: 0;
    padding: 56px var(--m);
  }

  .showcase__in {
    grid-row: 2;
  }

  .showcase__out {
    grid-row: 3;
  }

  .showcase textarea,
  .showcase__out [data-ui] {
    width: 100%;
  }

  .split-heading {
    grid-row: 1;
    padding: 0 var(--m) 40px;
  }

  .split-heading span,
  .split-heading span:last-child {
    position: static;
    color: inherit;
  }

  .steps,
  .catalog,
  .why {
    grid-template-columns: 1fr;
  }

  .steps__text,
  .stage,
  .catalog__list,
  .why__text,
  .why__ci {
    grid-column: 1;
  }

  .stage {
    position: static;
    display: grid;
    gap: 24px;
    min-height: 0;
    padding: var(--m);
  }

  .stage [data-ui] {
    display: grid;
    gap: 24px;
    background: none;
    width: 100%;
  }

  .stage__state {
    display: block;
    background: var(--bg);
    border-radius: 6px;
    overflow: hidden;
  }

  .step,
  .step:first-of-type {
    min-height: 0;
    padding: 40px 0 0;
  }

  .step h3,
  .step.is-active h3 {
    color: var(--ink);
  }

  .step h3 {
    font-size: var(--step-lead);
  }

  .catalog__groups {
    gap: 0 var(--m);
  }
}

@media (max-width: 640px) {
  .topbar {
    padding: 20px;
  }

  .topbar nav {
    gap: 20px;
  }

  .catalog__groups {
    grid-template-columns: 1fr;
  }

  .catalog li {
    min-height: 44px;
    align-items: center;
  }

  .catalog li {
    flex-wrap: wrap;
    gap: 2px 16px;
  }

  .catalog li > span:last-child {
    text-align: left;
    padding-left: 22px;
  }

  .close {
    grid-template-columns: 1fr 1fr;
    gap: 10px;
  }

  .close {
    grid-template-columns: 1fr;
  }

  .close__tile {
    grid-column: 1 / -1;
    grid-row: 1;
    padding: 32px 20px;
    border-radius: 0;
  }

  .close > .close__field {
    display: none;
  }

  [data-ui] .code {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
  }

  .close > .close__tile {
    min-height: 300px;
  }

  .footer {
    grid-template-columns: 1fr;
    gap: 8px;
    margin-top: 20svh;
  }

  .footer p:last-child {
    text-align: left;
  }
}

/* Guide: contents beside one reading column, centred as a block */

.topbar--static {
  position: static;
}

.guide {
  display: grid;
  grid-template-columns: 220px minmax(0, 760px);
  justify-content: center;
  gap: clamp(32px, 6vw, 96px);
  padding: 48px var(--m) 0;
}

.toc {
  position: sticky;
  top: 32px;
  align-self: start;
  display: grid;
  gap: 6px;
  font-size: var(--step-small);
}

.toc a {
  color: var(--ink);
  text-decoration: none;
  transition: color var(--t-hover) var(--ease-out);
}

.toc a:hover,
.toc a.is-current {
  color: var(--accent);
}

.toc__sub {
  padding-left: 14px;
}

.doc h1 {
  font-size: var(--step-head);
}

.doc__lead {
  max-width: 52ch;
  margin-top: 24px;
  font-size: var(--step-lead);
  line-height: 1.35;
  letter-spacing: -0.01em;
}

.doc section {
  margin-top: 96px;
  scroll-margin-top: 32px;
}

.doc h2 {
  margin-bottom: 24px;
  font-size: var(--step-lead);
  letter-spacing: -0.02em;
}

.doc h3 {
  margin: 56px 0 16px;
  font-size: var(--step-body);
  font-weight: 600;
  letter-spacing: 0;
  scroll-margin-top: 32px;
}

.doc p,
.doc ul {
  max-width: 68ch;
  margin: 0 0 20px;
}

.doc ul {
  padding-left: 1.2em;
}

.doc li {
  margin-bottom: 8px;
}

.doc p a,
.doc td a {
  text-decoration-color: var(--muted);
  text-underline-offset: 0.2em;
}

.doc p a:hover,
.doc td a:hover {
  color: var(--accent);
}

.doc p code,
.doc li code,
.doc td code {
  padding: 0.1em 0.3em;
  border-radius: 3px;
  background: var(--surface);
}

.doc pre.code {
  margin: 0 0 24px;
  border-radius: 6px;
  background: var(--deep);
}

.doc table {
  width: 100%;
  margin: 0 0 24px;
  border-collapse: collapse;
  font-size: var(--step-small);
}

.doc th,
.doc td {
  padding: 10px 12px 10px 0;
  border-bottom: 1px solid var(--surface-2);
  text-align: left;
  vertical-align: top;
}

.doc th {
  color: var(--muted);
  font-weight: 500;
}

@media (max-width: 960px) {
  .guide {
    grid-template-columns: minmax(0, 1fr);
  }

  .toc {
    position: static;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    padding: 20px;
    background: var(--surface);
  }

  .toc__sub {
    padding-left: 0;
  }

  .doc table {
    display: block;
    overflow-x: auto;
  }
}

.doc__head .button {
  margin-top: 32px;
}

.doc .fragment {
  margin: 0 0 24px;
  border-radius: 6px;
  overflow: hidden;
  background: var(--deep);
}

.doc .fragment pre.code {
  margin: 0;
  border-radius: 0;
}

.doc p code,
.doc li code {
  overflow-wrap: anywhere;
}

@media (max-width: 640px) {
  .doc pre.code {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
  }

  .doc .panel-bar code {
    overflow-wrap: anywhere;
  }
}

/* The guide is read by jumping around: its parts rise into place but are
   never hidden */
@media (prefers-reduced-motion: no-preference) {
  html.js .guide-page [data-reveal] {
    opacity: 1;
    transform: translateY(18px);
  }

  html.js .guide-page [data-reveal].is-in {
    transform: none;
  }
}

.doc .doc__lead {
  margin: 24px 0 0;
}

/* Headings set solid (line-height 1) overhang their box: keep them inside
   their section */
.catalog,
.showcase {
  padding-top: 12px;
}