:root {
  --color-canvas: oklch(96.8% 0.007 247.896);
  --color-surface: oklch(98.4% 0.003 247.858);
  --color-border: oklch(86.9% 0.022 252.894);
  --color-text: oklch(12.9% 0.042 264.695);

  /* General layout-y gubbins */
  --app-gutter: 1.5rem;
  --app-font-body: system-ui, Helvetica, Arial, sans-serif;
  --app-font-header: Unbounded, var(--app-font-body);

  /* Swatch grid */
  --grid-border-width: 1px;
  --grid-border-color: var(--color-border);

  /* WCAG scores */
  --score-background-color: oklch(27.9% 0.041 260.031);
  --score-text-color: #fff;
  --score-grade-text-colour: oklch(12.9% 0.042 264.695);
  --score-border-width: 1px;
  --score-border-color: var(--score-background-color);
  --score-outline-color: var(--score-text-color);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-canvas: oklch(12.9% 0.042 264.695);
    --color-surface: oklch(20.8% 0.042 265.755);
    --color-border: oklch(44.6% 0.043 257.281);
    --color-text: oklch(98.4% 0.003 247.858);
  }
}

* {
  box-sizing: border-box;
}

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

/** 
 * GENERIC STUFF
 */

h1 {
  margin-block-start: 0;
  font-family: var(--app-font-header);
  font-size: x-large;
  font-weight: 680;
  line-height: 1.1;
  text-wrap: balance;
}

h2 {
  margin-block-start: 0;
  font-family: var(--app-font-header);
  font-size: x-large;
  font-weight: 600;
  line-height: 1.25;
}

p {
  max-inline-size: 42em;
}

a {
  color: inherit;
  text-decoration: underline;
  text-decoration-thickness: 1px;
}

a:hover {
  text-decoration-thickness: 2px;
}

/**
 * APP LAYOUT
 */

.app {
  padding-block-start: var(--app-gutter);
  background-color: var(--color-canvas);
  font-family: var(--app-font-body);
  text-size-adjust: 100%;
  color-scheme: light dark;
}

.app__body {
  margin: 0;
  padding: 0;
  color: var(--color-text);
  background-color: transparent;
  text-wrap: pretty;
  line-height: 1.5;
}

.app__sidebar,
.app__footer {
  padding-block-end: var(--app-gutter);
  padding-inline: var(--app-gutter);
}

.app__sidebar {
  grid-area: sidebar;
}

.app__grid {
  grid-area: grid;
  container-type: inline-size;
}

.app__footer {
  grid-area: footer;
  font-size: smaller;
}

.app__footer ul {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: baseline;
  margin: 0;
  padding: 0;
  list-style: none;
}

.app__footer li:not(:last-child)::after {
  content: "·";
  margin-inline: 0.25em;
}

.app__footer img {
  inline-size: 1.25em;
  block-size: 1.25em;
  vertical-align: text-top;
}

@media (min-width: 60rem) {
  .app__body {
    display: grid;
    grid-template-columns: 20rem 1fr;
    grid-template-rows: 1fr auto;
    grid-template-areas: "sidebar grid" "footer grid";
  }
}

/**
 * WCAG SCORE LABELS
 */

.score {
  display: inline-flex;
  border: var(--score-border-width) solid var(--score-border-color);
  font-size: smaller;
  outline: var(--score-border-width) solid var(--score-outline-color);
}

.score__grade,
.score__ratio {
  padding-block: 0.15em;
  padding-inline: 0.4em;
}

.score__grade {
  color: var(--score-grade-text-colour);
}

.score__grade--AAA {
  background-color: #77dd77;
}

.score__grade--AA {
  background-color: #77dd77;
}

.score__grade--AAL {
  background-color: #efde78;
}

.score__grade--Fail {
  background-color: #de8978;
}

.score__ratio {
  color: var(--score-text-color);
  background-color: var(--score-background-color);
  font-variant-numeric: tabular-nums;
}

/**
 * GRID - COLOR LABELS 
 */

.color-label {
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  inline-size: var(--grid-swatch-size);
  padding-block: 1rem;
  padding-inline: 0.5rem;
  border-width: 0;
  border-block-start-width: 0.5rem;
  border-style: solid;
  border-color: var(--c);
  font-weight: 400;
  font-variant-numeric: tabular-nums;
}

/**
 * GRID - SWATCHES / PLACEHOLDERS
 */

.swatch,
.placeholder {
  inline-size: var(--grid-swatch-size);
  block-size: var(--grid-swatch-size);
}

.swatch {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  align-items: flex-start;
  padding: 0.5rem;
  background-color: var(--c1);
}

.swatch__sample {
  color: var(--c2);
  font-size: 2.5rem;
  line-height: 1;
}

.placeholder,
.grid thead td:first-child {
  background-color: var(--color-surface);
  background-image: linear-gradient(
    45deg,
    transparent 50%,
    var(--grid-border-color) calc(50%),
    transparent calc(50% + var(--grid-border-width))
  );
}

/**
 * GRID - LAYOUT
 */

.grid {
  --grid-swatch-size: 6rem;

  border: 0 solid var(--color-border);
  border-block-start-width: 1px;
  background-color: var(--color-surface);
  overflow: auto;
  -webkit-overflow-scrolling: touch;
}

@media (min-width: 60rem) {
  .grid {
    block-size: calc(100vh - var(--app-gutter));
    position: sticky;
    inset-block-start: var(--app-gutter);
    border-inline-start-width: 1px;
  }
}

@container (min-width: 50rem) {
  .grid {
    --grid-swatch-size: 7rem;
  }
}

.grid table {
  table-layout: fixed;
}

.grid :is(th, td) {
  padding: 0;
  border: 1px solid var(--grid-border-color);
}

.grid thead :is(th, td),
.grid tbody :is(th, td):first-child {
  position: sticky;
  background-color: var(--color-canvas);
}

.grid thead :is(th, td) {
  border-block-start: 0;
  inset-block-start: 0;
  z-index: 1;
}

.grid tr :is(th, td):first-child {
  border-inline-start: 0;
  inset-inline-start: 0;
}

.grid thead :is(th, td):first-child {
  z-index: 2;
}

/* Rotate color labels at the start of rows */
/* NOTE: This is bugged in WebKit, open issue is here: 
    https://bugs.webkit.org/show_bug.cgi?id=313826 */
.grid tbody .color-label {
  writing-mode: sideways-lr;
}

/** 
 * SIDEBAR - CARDS
 */

.card {
  margin-block-start: var(--app-gutter);
  padding: calc(var(--app-gutter) * 0.666);
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

/**
 * SIDEBAR - SCORE GUIDE
 */

.score-guide {
  margin: 0;
}

.score-guide :is(dt, dd) {
  margin: 0;
  padding: 0;
}

.score-guide dt:not(:first-child) {
  margin-block-start: 0.75rem;
}

.score-guide dd {
  margin-block-start: 0.25rem;
  font-size: smaller;
}

/**
  * SIDEBAR - COLORS FORM 
  */

.form {
}

.form__label,
.form__hint,
.form__input {
  margin-block-end: 0.5rem;
}

.form__label {
  display: block;
}

.form__hint {
  display: block;
  font-size: smaller;
}

.form__input,
.form__button {
  font: inherit;
  line-height: inherit;
}

.form__input {
  inline-size: 100%;
  min-block-size: 5lh;
  max-block-size: 20lh;
  padding: 0.5rem;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  background-color: transparent;
  font-variant-numeric: tabular-nums;
  resize: vertical;
  field-sizing: content;
}

.form__button {
  display: block;
  inline-size: 100%;
  padding: 0.5rem 1rem;
  border: 1px solid var(--color-text);
  color: var(--color-surface);
  background-color: var(--color-text);
  font-weight: bold;
  cursor: pointer;
}