/* ========================================
   CSS Custom Properties
   ======================================== */
:root {
  --base: oklch(0.18 0.012 70);
  --neutral: oklch(0.94 0.012 80);
  --primary: oklch(0.82 0.16 75);
  --secondary: oklch(0.55 0.02 70);
  --accent: oklch(0.88 0.1 78);

  --h1: 2.6rem;
  --text-xs: 0.78rem;
  --text-s: 0.9rem;
  --text-m: 1.05rem;
  --text-l: 1.4rem;
  --text-xl: 2rem;

  --heading-font-family: "Fraunces", Georgia, serif;
  --text-font-family: "IBM Plex Mono", ui-monospace, monospace;

  --space-xs: 0.4rem;
  --space-s: 0.75rem;
  --space-m: 1.25rem;
  --space-l: 2rem;
  --space-xl: 3rem;

  --content-width: 76rem;
  --radius: 0.6rem;
  --transition: 180ms cubic-bezier(0.4, 0, 0.2, 1);
  --focus-width: 2px;
  --focus-offset: 2px;
}

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

body {
  font-family: var(--text-font-family);
  line-height: 1.6;
  color: var(--neutral);
  background:
    radial-gradient(120% 80% at 80% -10%, oklch(from var(--primary) l c h / 0.12), transparent 60%),
    var(--base);
  min-height: 100dvh;
  display: grid;
  place-items: start center;
  padding: var(--space-l) var(--space-m) var(--space-xl);
}

h1, h2 { font-family: var(--heading-font-family); font-weight: 600; }

/* ========================================
   App shell
   ======================================== */
.app {
  width: 100%;
  max-width: var(--content-width);
  container-type: inline-size;
  container-name: app;
}

.app__header { margin-block-end: var(--space-l); }

.app__eyebrow {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.25em;
  color: var(--primary);
}

.app__title {
  font-size: var(--h1);
  line-height: 1.05;
  margin-block: var(--space-xs) var(--space-s);
  font-style: italic;
}

.app__lede {
  font-size: var(--text-s);
  color: var(--secondary);
  max-width: 42ch;
}

/* --- Global settings (root size + viewports) --- */
.settings {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-s) var(--space-l);
  margin-block-start: var(--space-m);
  padding: var(--space-s) var(--space-m);
  border: 1px solid oklch(from var(--neutral) l c h / 0.12);
  border-radius: var(--radius);
  background: oklch(from var(--neutral) l c h / 0.03);
}

.settings__item {
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-xs);
}

.settings__label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--secondary);
}

.settings__field {
  display: inline-flex;
  align-items: baseline;
  gap: 2px;
  border-bottom: 2px solid oklch(from var(--neutral) l c h / 0.18);
  transition: border-color var(--transition);

  &:focus-within { border-color: var(--primary); }
}

.settings__input {
  width: 3.5em;
  font-family: var(--text-font-family);
  font-size: var(--text-m);
  font-weight: 500;
  color: var(--neutral);
  background: none;
  border: none;
  padding-block: 2px;

  &:focus { outline: none; }
  &::-webkit-outer-spin-button,
  &::-webkit-inner-spin-button { opacity: 0.3; }
}

.settings__unit { font-size: var(--text-s); color: var(--secondary); }
.settings__sep { font-size: var(--text-s); color: var(--secondary); }

/* ========================================
   Tabs (ARIA tablist pattern)
   ======================================== */
.tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-block-end: var(--space-m);
  border-bottom: 1px solid oklch(from var(--neutral) l c h / 0.12);
}

.tabs__tab {
  font-family: var(--text-font-family);
  font-size: var(--text-s);
  color: var(--secondary);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: var(--space-s) var(--space-m);
  margin-bottom: -1px;
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition);

  &:hover { color: var(--neutral); }
  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
    border-radius: 4px;
  }
}

.tabs__tab[aria-selected="true"] {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.tabs__panel[hidden] { display: none; }

/* wide screens: inputs left, preview + history in a sticky right sidebar */
@container app (min-width: 64rem) {
  .tabs__panel:not([hidden]) {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 24rem);
    gap: var(--space-l);
    align-items: start;
  }

  .panel__aside {
    position: sticky;
    top: var(--space-m);
    max-height: calc(100dvh - var(--space-l));
    overflow-y: auto;
  }

  .panel__aside .preview { margin-block-start: 0; }
}

/* ========================================
   Controls
   ======================================== */
.controls {
  display: grid;
  gap: var(--space-m);
  padding: var(--space-m);
  border: 1px solid oklch(from var(--neutral) l c h / 0.12);
  border-radius: var(--radius);
  background: oklch(from var(--neutral) l c h / 0.03);

  @container app (min-width: 32rem) {
    grid-template-columns: 1fr 1fr;
  }
}
.controls[hidden] { display: none; }
.controls + .controls { margin-block-start: var(--space-s); }

.field { display: grid; gap: var(--space-xs); }
.field[hidden] { display: none; }

.field__label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--secondary);
}

.field__input-row {
  display: flex;
  align-items: baseline;
  gap: var(--space-xs);
  border-bottom: 2px solid oklch(from var(--neutral) l c h / 0.18);
  transition: border-color var(--transition);

  &:focus-within { border-color: var(--primary); }
}

.field__input {
  flex: 1;
  width: 100%;
  min-width: 0;
  font-family: var(--text-font-family);
  font-size: var(--text-xl);
  font-weight: 500;
  color: var(--neutral);
  background: none;
  border: none;
  padding-block: var(--space-xs);

  &:focus { outline: none; }
  &::-webkit-outer-spin-button,
  &::-webkit-inner-spin-button { opacity: 0.3; }
}

.field__unit { font-size: var(--text-m); color: var(--secondary); }

.field__select {
  font-family: var(--text-font-family);
  font-size: var(--text-l);
  font-weight: 500;
  color: var(--neutral);
  background: oklch(from var(--neutral) l c h / 0.04);
  border: none;
  border-bottom: 2px solid oklch(from var(--neutral) l c h / 0.18);
  padding: var(--space-xs);
  cursor: pointer;
  transition: border-color var(--transition);

  &:focus-visible { outline: none; border-color: var(--primary); }
}
.field__select option { background: var(--base); color: var(--neutral); }

.field__hint { font-size: var(--text-xs); color: var(--secondary); }

.field__input--name { font-size: var(--text-m); }

/* --- CSS variables output --- */
.vars {
  margin-block-start: var(--space-m);
  display: grid;
  gap: var(--space-m);
}
.vars[hidden] { display: none; }

.vars__output { display: grid; gap: var(--space-s); }

.vars__code {
  margin: 0;
  font-family: var(--text-font-family);
  font-size: var(--text-s);
  color: var(--accent);
  background: oklch(from var(--neutral) l c h / 0.05);
  border: 1px solid oklch(from var(--neutral) l c h / 0.12);
  border-radius: var(--radius);
  padding: var(--space-m);
  white-space: pre-wrap;
  word-break: break-word;
  overflow-x: auto;
}

.vars__output .copy-btn { justify-self: start; }

/* --- Toggle button (add line-height clamp) --- */
.toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  margin-block-start: var(--space-m);
  font-family: var(--text-font-family);
  font-size: var(--text-s);
  font-weight: 500;
  color: var(--primary);
  background: none;
  border: 1px dashed oklch(from var(--primary) l c h / 0.4);
  border-radius: var(--radius);
  padding: var(--space-s) var(--space-m);
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);

  &:hover { background: oklch(from var(--primary) l c h / 0.08); }
  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
  }
}

.toggle__icon {
  font-size: var(--text-m);
  line-height: 1;
  transition: transform var(--transition);
}
.toggle[aria-pressed="true"] {
  border-style: solid;
  background: oklch(from var(--primary) l c h / 0.1);
  margin-block-end: var(--space-m);
}
.toggle[aria-pressed="true"] .toggle__icon { transform: rotate(45deg); }

/* --- Result --- */
.result {
  margin-block-start: var(--space-m);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-m);
  padding: var(--space-m);
  border-radius: var(--radius);
  background: oklch(from var(--primary) l c h / 0.1);
  border: 1px solid oklch(from var(--primary) l c h / 0.3);
}
.result[hidden] { display: none; }

.result__group { display: grid; gap: 2px; flex: 1 1 18rem; }

.result__label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: oklch(from var(--primary) 0.7 c h);
}

.result__value {
  font-family: var(--heading-font-family);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--primary);
  font-variant-numeric: tabular-nums;
}

.result__value--clamp {
  font-family: var(--text-font-family);
  font-size: var(--text-m);
  line-height: 1.5;
  word-break: break-word;
}

.result__sub { font-size: var(--text-xs); color: var(--secondary); }

.copy-btn {
  font-family: var(--text-font-family);
  font-size: var(--text-s);
  font-weight: 500;
  color: var(--base);
  background: var(--primary);
  border: none;
  border-radius: var(--radius);
  padding: var(--space-s) var(--space-m);
  cursor: pointer;
  transition: transform var(--transition), background var(--transition);

  &:hover { background: var(--accent); }
  &:active { transform: scale(0.97); }
  &:focus-visible {
    outline: var(--focus-width) solid var(--neutral);
    outline-offset: var(--focus-offset);
  }
  &.copy-btn--copied { background: oklch(0.78 0.15 150); }
}

/* --- Preview --- */
.preview { margin-block-start: var(--space-l); }

.preview__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-s);
  margin-block-end: var(--space-s);
}

.preview__label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--secondary);
}

.preview__note { font-size: var(--text-xs); color: var(--secondary); }

.preview__sim { color: var(--primary); font-variant-numeric: tabular-nums; }

.preview__resize {
  resize: horizontal;
  overflow: hidden;
  min-width: min(14rem, 100%);
  max-width: 100%;
  /* room so the editable text's focus outline isn't clipped by overflow: hidden */
  padding: calc(var(--focus-width) + var(--focus-offset));
  background-image: linear-gradient(135deg, transparent 50%, oklch(from var(--primary) l c h / 0.6) 50%);
  background-repeat: no-repeat;
  background-position: bottom right;
  background-size: 11px 11px;
}

.preview__text {
  font-family: var(--heading-font-family);
  color: var(--neutral);
  padding: var(--space-m);
  border: 1px dashed oklch(from var(--neutral) l c h / 0.18);
  border-radius: var(--radius);

  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
  }
}

.footnote {
  margin-block-start: var(--space-l);
  font-size: var(--text-xs);
  color: var(--secondary);
  line-height: 1.7;
}
.footnote code {
  color: var(--accent);
  background: oklch(from var(--neutral) l c h / 0.06);
  padding: 0 0.3em;
  border-radius: 3px;
}

/* --- History --- */
.history { margin-block-start: var(--space-l); }

.history__head {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-s) var(--space-m);
  margin-block-end: var(--space-s);
}

.history__label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--secondary);
}

.history__recalc {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-xs);
  color: var(--secondary);
  cursor: pointer;
}

.history__checkbox { accent-color: var(--primary); }

.history__actions {
  margin-inline-start: auto;
  display: inline-flex;
  gap: var(--space-xs);
}

.history__btn {
  font-family: var(--text-font-family);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--primary);
  background: none;
  border: 1px solid oklch(from var(--primary) l c h / 0.4);
  border-radius: var(--radius);
  padding: var(--space-xs) var(--space-s);
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);

  &:hover { background: oklch(from var(--primary) l c h / 0.08); }
  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
  }
}

.history__btn--quiet {
  color: var(--secondary);
  border-color: oklch(from var(--neutral) l c h / 0.18);

  &:hover { background: oklch(from var(--neutral) l c h / 0.06); }
}

.history__list {
  list-style: none;
  display: grid;
  gap: var(--space-xs);
}

.history__empty {
  font-size: var(--text-xs);
  color: var(--secondary);
  padding-block: var(--space-s);
}

.history__item {
  display: flex;
  align-items: stretch;
  gap: var(--space-xs);
}

.history__entry {
  flex: 1;
  min-width: 0;
  display: grid;
  gap: var(--space-xs);
  text-align: left;
  font-family: var(--text-font-family);
  background: oklch(from var(--neutral) l c h / 0.03);
  border: 1px solid oklch(from var(--neutral) l c h / 0.12);
  border-radius: var(--radius);
  padding: var(--space-s) var(--space-m);
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);

  &:hover {
    border-color: oklch(from var(--primary) l c h / 0.5);
    background: oklch(from var(--primary) l c h / 0.05);
  }
  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
  }
}

.history__meta {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-xs);
  font-size: var(--text-xs);
  color: var(--secondary);
}

.history__time { white-space: nowrap; }

.history__code {
  font-size: var(--text-xs);
  color: var(--accent);
  white-space: pre-wrap;
  word-break: break-word;
}

.history__delete {
  flex: none;
  align-self: center;
  width: 1.8rem;
  height: 1.8rem;
  font-family: var(--text-font-family);
  font-size: var(--text-s);
  line-height: 1;
  color: var(--secondary);
  background: none;
  border: 1px solid oklch(from var(--neutral) l c h / 0.18);
  border-radius: var(--radius);
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition);

  &:hover { color: var(--neutral); border-color: oklch(from var(--neutral) l c h / 0.4); }
  &:focus-visible {
    outline: var(--focus-width) solid var(--primary);
    outline-offset: var(--focus-offset);
  }
}

.visually-hidden {
  position: absolute; width: 1px; height: 1px;
  overflow: hidden; clip: rect(0 0 0 0);
}