08Unit toggle that converts every number on the card at once

<main class="stage stage--paper">
  <section class="ut is-demo" id="ut" aria-label="Choose temperature units">
    <header class="ut__head">
      <p class="ut__title">Seoul temperatures</p>
      <div class="ut__seg" role="group" aria-label="Temperature unit">
        <span class="ut__thumb" aria-hidden="true"></span>
        <button class="ut__u is-on" type="button" data-unit="c" aria-pressed="true">°C</button>
        <button class="ut__u" type="button" data-unit="f" aria-pressed="false">°F</button>
      </div>
    </header>
    <p class="ut__big"><output class="ut__swap"><span class="ut__v ut-c" data-c="24">24</span><span class="ut__alt" aria-hidden="true">75</span></output><span class="ut__deg ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></p>
    <ul class="ut__hours">
      <li class="ut__h"><span class="ut__hl">Now</span><span class="ut__ht ut__swap"><span class="ut__v ut-c" data-c="24">24</span><span class="ut__alt" aria-hidden="true">75</span></span><span class="ut__hs ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
      <li class="ut__h"><span class="ut__hl">3 PM</span><span class="ut__ht ut__swap"><span class="ut__v ut-c" data-c="25">25</span><span class="ut__alt" aria-hidden="true">77</span></span><span class="ut__hs ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
      <li class="ut__h"><span class="ut__hl">4 PM</span><span class="ut__ht ut__swap"><span class="ut__v ut-c" data-c="23">23</span><span class="ut__alt" aria-hidden="true">73</span></span><span class="ut__hs ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
      <li class="ut__h"><span class="ut__hl">5 PM</span><span class="ut__ht ut__swap"><span class="ut__v ut-c" data-c="21">21</span><span class="ut__alt" aria-hidden="true">70</span></span><span class="ut__hs ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
    </ul>
    <ul class="ut__days">
      <li class="ut__d"><span class="ut__dl">Today</span><span class="ut__dv ut__swap"><span class="ut__v ut-c" data-c="18">18</span><span class="ut__alt" aria-hidden="true">64</span></span><span class="ut__dd">/</span><span class="ut__dv ut__swap"><span class="ut__v ut-c" data-c="27">27</span><span class="ut__alt" aria-hidden="true">81</span></span><span class="ut__ds ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
      <li class="ut__d"><span class="ut__dl">Saturday</span><span class="ut__dv ut__swap"><span class="ut__v ut-c" data-c="17">17</span><span class="ut__alt" aria-hidden="true">63</span></span><span class="ut__dd">/</span><span class="ut__dv ut__swap"><span class="ut__v ut-c" data-c="29">29</span><span class="ut__alt" aria-hidden="true">84</span></span><span class="ut__ds ut__swap"><span class="ut__v ut-suffix">°C</span><span class="ut__alt" aria-hidden="true">°F</span></span></li>
    </ul>
  </section>
</main>

@use "../../../../site/static/demo-tokens" as *;

// 단위 토글 — 고르면 카드 안 모든 숫자가 같은 순간에 환산된다.
// 미리보기 루프도 카드의 모든 숫자·접미사를 한 컷(steps(1,end))에 같이 바꾼다 — 큰 온도만 바꾸면
// 「75°F 옆에 24°C 칸」이라는 실사용에 없는 장면이 poster 로 뽑힌다. 실제 환산은 JS 가 전 칸에 한다.
$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-paper);

.ut {
  box-sizing: border-box;
  display: grid;
  gap: $sp-2;
  width: min(264px, 92vw);
  padding: $sp-3;
  border: 1px solid rgba(23, 20, 26, .12);
  border-radius: $r-card;
  background: $stage-paper;
  color: $subject-ink;
  box-shadow: $shadow-press;
}
.ut * { box-sizing: border-box; }

.ut__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: $sp-2;
}
.ut__title {
  margin: 0;
  font-size: 13px;
  font-weight: 700;
  line-height: 1.3;
}

// 두 단위 세그먼트 — 엄지가 칸을 옮겨 다닌다 (translateX 고정폭, 칸은 2칸 grid)
.ut__seg {
  position: relative;
  display: grid;
  grid-template-columns: repeat(2, 36px);
  padding: $sp-1;
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .08);
}
.ut__thumb {
  position: absolute;
  top: $sp-1;
  left: $sp-1;
  width: 36px;
  height: calc(100% - 8px);
  border-radius: $r-pill;
  background: $subject-ink;
  transition: transform $dur-quick $easing;
}
.ut.is-f .ut__thumb { transform: translateX(36px); }
.ut__u {
  position: relative;
  z-index: 1;
  padding: $sp-1 0;
  border: 0;
  background: none;
  color: rgba($subject-ink, .72);
  font-size: 11px;
  font-weight: 700;
  line-height: 1.3;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
  &:focus-visible { outline: 2px solid $subject-blue; outline-offset: 2px; border-radius: $r-pill; }
  &.is-on { color: $subject-cream; }
}

.ut__big {
  display: flex;
  align-items: flex-start;
  margin: 0;
  font-size: 44px;
  font-weight: 800;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.ut__deg {
  font-size: 20px;
  font-weight: 700;
}

.ut__hours {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: $sp-1;
  margin: 0;
  padding: 0;
  list-style: none;
}
.ut__h {
  display: grid;
  justify-items: center;
  gap: $sp-1;
  padding: $sp-1 0;
  border-radius: $r-control;
  background: rgba(110, 200, 255, .2);
  font-variant-numeric: tabular-nums;
}
.ut__hl {
  font-size: 9px;
  font-weight: 700;
  line-height: 1;
  color: rgba($subject-ink, .72);
}
.ut__ht {
  font-size: 13px;
  font-weight: 800;
  line-height: 1.2;
}
.ut__hs {
  font-size: 9px;
  font-weight: 500;
  line-height: 1;
  color: rgba($subject-ink, .72);
}

.ut__days {
  display: grid;
  gap: $sp-1;
  margin: 0;
  padding: 0;
  list-style: none;
}
.ut__d {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: $sp-2;
  font-variant-numeric: tabular-nums;
}
.ut__dl {
  font-size: 10px;
  font-weight: 700;
  line-height: 1.3;
  color: rgba($subject-ink, .72);
}
.ut__dv {
  font-size: 12px;
  font-weight: 700;
  line-height: 1.3;
}
.ut__dd { color: rgba($subject-ink, .72); }
.ut__ds {
  font-size: 10px;
  color: rgba($subject-ink, .72);
}

// 겹쳐 둔 두 번째 값 — 미리보기 루프에서만 보인다
.ut__swap { position: relative; display: inline-block; }
.ut__alt {
  position: absolute;
  inset: 0;
  opacity: 0;
}

// ── 격자 미리보기 루프 (2초) ──
// 0~44% 섭씨 → 45% 컷으로 화씨(엄지 이동·강조 맞바뀜 함께) → 88% 섭씨 복귀.
@keyframes ut-va { 0%, 44% { opacity: 1; } 45%, 87% { opacity: 0; } 88%, 100% { opacity: 1; } }
@keyframes ut-vb { 0%, 44% { opacity: 0; } 45%, 87% { opacity: 1; } 88%, 100% { opacity: 0; } }
@keyframes ut-thumb {
  0%, 42% { transform: translateX(0); }
  56%, 84% { transform: translateX(36px); }
  96%, 100% { transform: translateX(0); }
}
@keyframes ut-suffix {
  0%, 44% { opacity: 1; }
  45%, 87% { opacity: 0; }
  88%, 100% { opacity: 1; }
}
@keyframes ut-pressf {
  0%, 41% { transform: scale(1); }
  45% { transform: scale(.9); }
  57%, 100% { transform: scale(1); }
}
// 강조도 같은 컷에 맞바뀐다 — 엄지만 옮기면 엄지 밑 글자가 어두운 채로 묻히고
// 반대쪽 크림 글자는 밝은 바닥에서 사라져 토글이 빈 알약으로 찍힌다(poster 실측).
@keyframes ut-labelc {
  0%, 44% { color: $subject-cream; }
  45%, 87% { color: rgba($subject-ink, .72); }
  88%, 100% { color: $subject-cream; }
}
@keyframes ut-labelf {
  0%, 44% { color: rgba($subject-ink, .72); }
  45%, 87% { color: $subject-cream; }
  88%, 100% { color: rgba($subject-ink, .72); }
}
.ut.is-demo {
  .ut__swap .ut__v { animation-name: ut-va; }
  .ut__swap .ut__alt { animation-name: ut-vb; }
  .ut__swap .ut__v, .ut__swap .ut__alt {
    animation-duration: $duration;
    animation-timing-function: steps(1, end);
    animation-iteration-count: infinite;
    animation-fill-mode: backwards;
  }
  .ut__thumb {
    animation-name: ut-thumb;
    animation-duration: $duration;
    animation-timing-function: $easing;
    animation-iteration-count: infinite;
    animation-fill-mode: backwards;
  }
  // 접미사 °C/°F 도 숫자와 같은 컷 스왑 — 겹쳐 보이는 순간이 없게
  .ut__deg .ut__v, .ut__deg .ut__alt {
    animation-name: ut-va, ut-vb;
    animation-duration: $duration, $duration;
    animation-timing-function: steps(1, end), steps(1, end);
    animation-iteration-count: infinite, infinite;
    animation-fill-mode: backwards, backwards;
  }
  .ut__deg .ut__v { animation-name: ut-va; }
  .ut__deg .ut__alt { animation-name: ut-vb; }
  .ut__seg .ut__u[data-unit='c'] {
    animation-name: ut-labelc;
    animation-duration: $duration;
    animation-timing-function: steps(1, end);
    animation-iteration-count: infinite;
    animation-fill-mode: backwards;
  }
  .ut__seg .ut__u[data-unit='f'] {
    animation-name: ut-pressf, ut-labelf;
    animation-duration: $duration, $duration;
    animation-timing-function: $easing, steps(1, end);
    animation-iteration-count: infinite, infinite;
    animation-fill-mode: backwards, backwards;
  }
}

@media (max-width: 340px) {
  .ut { padding: $sp-1 $sp-2; gap: $sp-1; }
  .ut__big { font-size: 30px; }
  .ut__deg { font-size: 16px; }
  .ut__h { padding: 0; }
  .ut__d { gap: $sp-1; }
  .ut__dv { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .ut.is-demo .ut__swap .ut__v,
  .ut.is-demo .ut__swap .ut__alt,
  .ut.is-demo .ut__thumb,
  .ut.is-demo .ut__u {
    animation: none !important;
    transform: none !important;
  }
  .ut.is-demo .ut__swap .ut__v { opacity: 1 !important; }
  .ut.is-demo .ut__swap .ut__alt { opacity: 0 !important; }
  .ut__thumb { transition: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ut {
  box-sizing: border-box;
  display: grid;
  gap: 8px;
  width: min(264px, 92vw);
  padding: 12px;
  border: 1px solid rgba(23, 20, 26, 0.12);
  border-radius: 16px;
  background: #ffffff;
  color: #17141a;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.ut * {
  box-sizing: border-box;
}

.ut__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.ut__title {
  margin: 0;
  font-size: 13px;
  font-weight: 700;
  line-height: 1.3;
}

.ut__seg {
  position: relative;
  display: grid;
  grid-template-columns: repeat(2, 36px);
  padding: 4px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.08);
}

.ut__thumb {
  position: absolute;
  top: 4px;
  left: 4px;
  width: 36px;
  height: calc(100% - 8px);
  border-radius: 999px;
  background: #17141a;
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.ut.is-f .ut__thumb {
  transform: translateX(36px);
}

.ut__u {
  position: relative;
  z-index: 1;
  padding: 4px 0;
  border: 0;
  background: none;
  color: rgba(23, 20, 26, 0.72);
  font-size: 11px;
  font-weight: 700;
  line-height: 1.3;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
}
.ut__u:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
  border-radius: 999px;
}
.ut__u.is-on {
  color: #fff7e6;
}

.ut__big {
  display: flex;
  align-items: flex-start;
  margin: 0;
  font-size: 44px;
  font-weight: 800;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.ut__deg {
  font-size: 20px;
  font-weight: 700;
}

.ut__hours {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.ut__h {
  display: grid;
  justify-items: center;
  gap: 4px;
  padding: 4px 0;
  border-radius: 12px;
  background: rgba(110, 200, 255, 0.2);
  font-variant-numeric: tabular-nums;
}

.ut__hl {
  font-size: 9px;
  font-weight: 700;
  line-height: 1;
  color: rgba(23, 20, 26, 0.72);
}

.ut__ht {
  font-size: 13px;
  font-weight: 800;
  line-height: 1.2;
}

.ut__hs {
  font-size: 9px;
  font-weight: 500;
  line-height: 1;
  color: rgba(23, 20, 26, 0.72);
}

.ut__days {
  display: grid;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.ut__d {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  font-variant-numeric: tabular-nums;
}

.ut__dl {
  font-size: 10px;
  font-weight: 700;
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.72);
}

.ut__dv {
  font-size: 12px;
  font-weight: 700;
  line-height: 1.3;
}

.ut__dd {
  color: rgba(23, 20, 26, 0.72);
}

.ut__ds {
  font-size: 10px;
  color: rgba(23, 20, 26, 0.72);
}

.ut__swap {
  position: relative;
  display: inline-block;
}

.ut__alt {
  position: absolute;
  inset: 0;
  opacity: 0;
}

@keyframes ut-va {
  0%, 44% {
    opacity: 1;
  }
  45%, 87% {
    opacity: 0;
  }
  88%, 100% {
    opacity: 1;
  }
}
@keyframes ut-vb {
  0%, 44% {
    opacity: 0;
  }
  45%, 87% {
    opacity: 1;
  }
  88%, 100% {
    opacity: 0;
  }
}
@keyframes ut-thumb {
  0%, 42% {
    transform: translateX(0);
  }
  56%, 84% {
    transform: translateX(36px);
  }
  96%, 100% {
    transform: translateX(0);
  }
}
@keyframes ut-suffix {
  0%, 44% {
    opacity: 1;
  }
  45%, 87% {
    opacity: 0;
  }
  88%, 100% {
    opacity: 1;
  }
}
@keyframes ut-pressf {
  0%, 41% {
    transform: scale(1);
  }
  45% {
    transform: scale(0.9);
  }
  57%, 100% {
    transform: scale(1);
  }
}
@keyframes ut-labelc {
  0%, 44% {
    color: #fff7e6;
  }
  45%, 87% {
    color: rgba(23, 20, 26, 0.72);
  }
  88%, 100% {
    color: #fff7e6;
  }
}
@keyframes ut-labelf {
  0%, 44% {
    color: rgba(23, 20, 26, 0.72);
  }
  45%, 87% {
    color: #fff7e6;
  }
  88%, 100% {
    color: rgba(23, 20, 26, 0.72);
  }
}
.ut.is-demo .ut__swap .ut__v {
  animation-name: ut-va;
}
.ut.is-demo .ut__swap .ut__alt {
  animation-name: ut-vb;
}
.ut.is-demo .ut__swap .ut__v, .ut.is-demo .ut__swap .ut__alt {
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
  animation-fill-mode: backwards;
}
.ut.is-demo .ut__thumb {
  animation-name: ut-thumb;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
  animation-fill-mode: backwards;
}
.ut.is-demo .ut__deg .ut__v, .ut.is-demo .ut__deg .ut__alt {
  animation-name: ut-va, ut-vb;
  animation-duration: 2s, 2s;
  animation-timing-function: steps(1, end), steps(1, end);
  animation-iteration-count: infinite, infinite;
  animation-fill-mode: backwards, backwards;
}
.ut.is-demo .ut__deg .ut__v {
  animation-name: ut-va;
}
.ut.is-demo .ut__deg .ut__alt {
  animation-name: ut-vb;
}
.ut.is-demo .ut__seg .ut__u[data-unit=c] {
  animation-name: ut-labelc;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
  animation-fill-mode: backwards;
}
.ut.is-demo .ut__seg .ut__u[data-unit=f] {
  animation-name: ut-pressf, ut-labelf;
  animation-duration: 2s, 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1), steps(1, end);
  animation-iteration-count: infinite, infinite;
  animation-fill-mode: backwards, backwards;
}

@media (max-width: 340px) {
  .ut {
    padding: 4px 8px;
    gap: 4px;
  }
  .ut__big {
    font-size: 30px;
  }
  .ut__deg {
    font-size: 16px;
  }
  .ut__h {
    padding: 0;
  }
  .ut__d {
    gap: 4px;
  }
  .ut__dv {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ut.is-demo .ut__swap .ut__v,
  .ut.is-demo .ut__swap .ut__alt,
  .ut.is-demo .ut__thumb,
  .ut.is-demo .ut__u {
    animation: none !important;
    transform: none !important;
  }
  .ut.is-demo .ut__swap .ut__v {
    opacity: 1 !important;
  }
  .ut.is-demo .ut__swap .ut__alt {
    opacity: 0 !important;
  }
  .ut__thumb {
    transition: none !important;
  }
}

// 단위를 고르면 카드 안 모든 온도가 같은 순간에 환산되고, 고른 값은 저장돼 다음에 열어도 그대로다.
var utRoot = document.getElementById('ut');
var utCells = utRoot.querySelectorAll('.ut-c');
var utSuffixes = utRoot.querySelectorAll('.ut-suffix');
var utButtons = utRoot.querySelectorAll('.ut__u');
function utShow(unit) {
  for (var i = 0; i < utCells.length; i++) {
    var c = Number(utCells[i].getAttribute('data-c'));
    utCells[i].textContent = unit === 'f' ? String(Math.round(c * 9 / 5 + 32)) : String(c);
  }
  for (var j = 0; j < utSuffixes.length; j++) {
    utSuffixes[j].textContent = unit === 'f' ? '°F' : '°C';
  }
  for (var k = 0; k < utButtons.length; k++) {
    var on = utButtons[k].getAttribute('data-unit') === unit;
    utButtons[k].classList.toggle('is-on', on);
    utButtons[k].setAttribute('aria-pressed', on ? 'true' : 'false');
  }
  utRoot.classList.toggle('is-f', unit === 'f');
}
function utRemember(unit) {
  try { localStorage.setItem('ut-unit', unit); } catch (err) { /* 저장이 막힌 창에서는 이번 화면만 */ }
}
utRoot.addEventListener('click', function (e) {
  var btn = e.target.closest('.ut__u');
  if (!btn) return;
  utRoot.classList.remove('is-demo');
  var unit = btn.getAttribute('data-unit');
  utShow(unit);
  utRemember(unit);
});
// 저장돼 있던 단위를 되살린다 — 없으면 섭씨
var utSaved = null;
try { utSaved = localStorage.getItem('ut-unit'); } catch (err2) { utSaved = null; }
utShow(utSaved === 'f' ? 'f' : 'c');

import { useEffect, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./WeatherUnitToggle.module.scss";

// vanilla 판(run/281/demo/08-weather-unit-toggle/index.html) 의 React 포트.
// 단위를 고르면 카드 안 모든 온도가 같은 순간에 환산되고, 고른 값은 저장돼 다음에 열어도 그대로다.

export type UtHour = {
  /** 칸 라벨("지금", "15시" …) — 언어팩이 통째로 바꾼다 */
  label: string;
  /** 섭씨 원본값 */
  c: number;
};

export type UtDay = {
  label: string;
  lo: number;
  hi: number;
};

export type WeatherUnitToggleProps = {
  title?: string;
  groupLabel?: string;
  segLabel?: string;
  celsiusLabel?: string;
  fahrenheitLabel?: string;
  /** 큰 온도 — 섭씨 원본값 */
  big?: number;
  hours?: UtHour[];
  days?: UtDay[];
  /** 저장 열쇠 — 브라우저마다 이 이름으로 단위를 기억한다 */
  storageKey?: string;
  /** 격자 미리보기 2초 자동 루프. 사람이 손대면 꺼진다 */
  demo?: boolean;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

const DEFAULT_HOURS: UtHour[] = [
  { label: "지금", c: 24 },
  { label: "15시", c: 25 },
  { label: "16시", c: 23 },
  { label: "17시", c: 21 },
];

const DEFAULT_DAYS: UtDay[] = [
  { label: "오늘", lo: 18, hi: 27 },
  { label: "토요일", lo: 17, hi: 29 },
];

function toF(c: number): number {
  return Math.round((c * 9) / 5 + 32);
}

function loadUnit(key: string): string {
  try {
    return localStorage.getItem(key) || "";
  } catch (e) {
    // 저장이 막힌 창에서는 이번 화면만
    return "";
  }
}
function saveUnit(key: string, unit: string): void {
  try {
    localStorage.setItem(key, unit);
  } catch (e) {
    /* 저장이 막힌 창에서는 이번 화면만 */
  }
}

export default function WeatherUnitToggle({
  title = "서울의 온도",
  groupLabel = "온도 단위 고르기",
  segLabel = "온도 단위",
  celsiusLabel = "°C",
  fahrenheitLabel = "°F",
  big = 24,
  hours = DEFAULT_HOURS,
  days = DEFAULT_DAYS,
  storageKey = "ut-unit",
  demo = true,
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: WeatherUnitToggleProps) {
  const [unit, setUnit] = useState("c");
  const [live, setLive] = useState(demo);

  // 저장돼 있던 단위를 되살린다 — 없으면 섭씨
  useEffect(() => {
    if (loadUnit(storageKey) === "f") setUnit("f");
  }, []);

  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  const isF = unit === "f";
  const suffix = isF ? fahrenheitLabel : celsiusLabel;
  const show = (c: number): number => (isF ? toF(c) : c);

  function pick(next: string): void {
    setLive(false);
    setUnit(next);
    saveUnit(storageKey, next);
  }

  const cls = [styles.ut, live ? styles.isDemo : "", isF ? styles.isF : ""].filter(Boolean).join(" ");

  return (
    <main className={styles.stage}>
      <section className={cls} style={vars} aria-label={groupLabel}>
        <header className={styles.head}>
          <p className={styles.title}>{title}</p>
          <div className={styles.seg} role="group" aria-label={segLabel}>
            <span className={styles.thumb} aria-hidden="true" />
            <button
              className={[styles.u, styles.uC, !isF ? styles.isOn : ""].filter(Boolean).join(" ")}
              type="button"
              aria-pressed={!isF ? "true" : "false"}
              onClick={() => pick("c")}
            >{celsiusLabel}</button>
            <button
              className={[styles.u, styles.uF, isF ? styles.isOn : ""].filter(Boolean).join(" ")}
              type="button"
              aria-pressed={isF ? "true" : "false"}
              onClick={() => pick("f")}
            >{fahrenheitLabel}</button>
          </div>
        </header>
        <p className={styles.big}>
          <output className={styles.swap}>
            <span className={styles.v}>{show(big)}</span>
            <span className={styles.alt} aria-hidden="true">{isF ? big : toF(big)}</span>
          </output>
          <span className={`${styles.deg} ${styles.swap}`}>
            <span className={styles.v}>{suffix}</span>
            <span className={styles.alt} aria-hidden="true">{isF ? celsiusLabel : fahrenheitLabel}</span>
          </span>
        </p>
        <ul className={styles.hours}>
          {hours.map((h: UtHour) => (
            <li className={styles.h} key={h.label}>
              <span className={styles.hl}>{h.label}</span>
              <span className={`${styles.ht} ${styles.swap}`}>
                <span className={styles.v}>{show(h.c)}</span>
                <span className={styles.alt} aria-hidden="true">{isF ? h.c : toF(h.c)}</span>
              </span>
              <span className={`${styles.hs} ${styles.swap}`}>
                <span className={styles.v}>{suffix}</span>
                <span className={styles.alt} aria-hidden="true">{isF ? celsiusLabel : fahrenheitLabel}</span>
              </span>
            </li>
          ))}
        </ul>
        <ul className={styles.days}>
          {days.map((d: UtDay) => (
            <li className={styles.d} key={d.label}>
              <span className={styles.dl}>{d.label}</span>
              <span className={`${styles.dv} ${styles.swap}`}>
                <span className={styles.v}>{show(d.lo)}</span>
                <span className={styles.alt} aria-hidden="true">{isF ? d.lo : toF(d.lo)}</span>
              </span>
              <span className={styles.dd}>/</span>
              <span className={`${styles.dv} ${styles.swap}`}>
                <span className={styles.v}>{show(d.hi)}</span>
                <span className={styles.alt} aria-hidden="true">{isF ? d.hi : toF(d.hi)}</span>
              </span>
              <span className={`${styles.ds} ${styles.swap}`}>
                <span className={styles.v}>{suffix}</span>
                <span className={styles.alt} aria-hidden="true">{isF ? celsiusLabel : fahrenheitLabel}</span>
              </span>
            </li>
          ))}
        </ul>
      </section>
    </main>
  );
}