:root {
  color-scheme: light dark;
  --chapter-1: #f5f5f7;
  --chapter-2: #000;
  --chapter-3: #fff;
  --chapter-4: #f5f5f7;
  --surface: #fff;
  --raised: #f5f5f7;
  --ink: #1d1d1f;
  --muted: #6e6e73;
  --accent: #0066cc;
  --focus: #0071e3;
  --fill: rgba(118, 118, 128, 0.12);
  --line: rgba(60, 60, 67, 0.18);
  --gain: #d70015; /* 台灣慣例：紅色代表上漲與獲利 */
  --bar: rgba(251, 251, 253, 0.8);
  --warn-bg: #fff4d6;
  --warn-text: #5c4300;

  /* 深色面：結果卡和費率章節，淺色模式也維持深色 */
  --tile: #1d1d1f;
  --tile-ink: #f5f5f7;
  --tile-muted: #a1a1a6;
  --tile-line: rgba(255, 255, 255, 0.16);
  --tile-gain: #ff6961;
  --tile-loss: #30d158;
  --tile-warn-bg: #3d3010;
  --tile-warn-text: #ffe29a;

  --gutter: clamp(1rem, 4vw, 2rem);
  --frame: 64rem;
  --edge: max(var(--gutter), calc((100% - var(--frame)) / 2));
  --radius: 1.5rem;
  --bar-height: 3rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --chapter-1: #000;
    --chapter-2: #161617;
    --chapter-3: #000;
    --chapter-4: #161617;
    --surface: #1c1c1e;
    --raised: #1c1c1e;
    --ink: #f5f5f7;
    --muted: #a1a1a6;
    --accent: #2997ff;
    --focus: #2997ff;
    --line: rgba(255, 255, 255, 0.16);
    --gain: #ff6961;
    --bar: rgba(22, 22, 23, 0.8);
    --warn-bg: #3d3010;
    --warn-text: #ffe29a;
    --tile: #1c1c1e;
  }
}

* { box-sizing: border-box; corner-shape: squircle; }

html { scroll-padding-top: calc(var(--bar-height) + 1rem); }

body {
  margin: 0;
  background: var(--chapter-1);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, system-ui, "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

p { text-wrap: pretty; }
a { color: var(--accent); }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }

h1, h2, h3 { font-weight: 600; }

h1 {
  margin: 0;
  font-size: clamp(2.25rem, 10vw, 5.5rem);
  line-height: 1.08;
  letter-spacing: -0.02em;
}

h2 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.5rem);
  line-height: 1.1;
  letter-spacing: -0.015em;
}

h3 {
  margin: 0;
  font-size: 1.3125rem;
  line-height: 1.35;
  letter-spacing: -0.005em;
}

/* 導覽列：內容從下方捲過的半透明材質 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0 0.5rem;
  min-height: var(--bar-height);
  padding-inline: var(--edge);
  background: var(--bar);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
}

.brand {
  color: var(--ink);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}

.site-header nav { display: flex; flex-wrap: wrap; gap: 0 clamp(0.75rem, 3vw, 1.75rem); }

.site-header nav a {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  color: var(--ink);
  font-size: 0.8125rem;
  text-decoration: none;
  white-space: nowrap;
}

.site-header nav a:hover { color: var(--accent); }

/* 章節：全幅色塊，內容共用同一組左右邊界 */
.chapter { padding: clamp(4.5rem, 10vw, 9rem) var(--edge); }

.hero {
  padding-block: clamp(1.75rem, 5vw, 3.5rem) clamp(4.5rem, 10vw, 7rem);
  background: var(--chapter-1);
  text-align: center;
}

.lead {
  max-width: 38em;
  margin: 1.25rem auto 0;
  color: var(--muted);
  font-size: clamp(1.125rem, 2vw, 1.3125rem);
  line-height: 1.5;
  text-wrap: balance;
}

.tool {
  display: grid;
  gap: 1rem;
  margin-top: clamp(1.5rem, 4vw, 3rem);
  text-align: left;
}

.tool > *, .rates > * { min-width: 0; } /* 格線項目預設不縮小，內容會把頁面撐寬 */

/* 計算機是真實介面，沿用 iOS 分組列表的慣例。手機上列高收緊，讓結果更靠近輸入處 */
#calc[data-ui] {
  padding: 0.25rem clamp(1rem, 3vw, 1.75rem);
  background: var(--surface);
  border-radius: var(--radius);
}

[data-ui] .field {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
  column-gap: 0.75rem;
  align-items: center;
  align-content: center;
  padding-block: 0.5rem;
}

[data-ui] .field + .field { border-top: 1px solid var(--line); }

[data-ui] label { grid-column: 1; font-weight: 500; line-height: 1.35; }
[data-ui] .field:has(.hint) label { align-self: end; }

[data-ui] input,
[data-ui] select {
  grid-column: 2;
  width: 100%;
  min-height: 2.75rem;
  padding: 0 0.75rem;
  background-color: var(--fill);
  color: var(--ink);
  border: 0;
  border-radius: 0.625rem;
  font: inherit; /* 字級維持 16px 以上，避免 iOS 聚焦時自動放大 */
  font-variant-numeric: tabular-nums;
  text-align: right;
}

/* 有提示文字時輸入框跨兩列；沒有提示時不跨列，標籤才會垂直置中 */
[data-ui] .field:has(.hint) > :is(input, select) { grid-row: 1 / span 2; }

[data-ui] select {
  padding-right: 2rem;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8'%3E%3Cpath d='M1 1.5l5 5 5-5' fill='none' stroke='%238e8e93' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-position: right 0.75rem center;
  background-repeat: no-repeat;
  text-align-last: right;
}

[data-ui] input:focus-visible,
[data-ui] select:focus-visible { outline-offset: 0; }

[data-ui] input[aria-invalid] { box-shadow: inset 0 0 0 2px var(--gain); }

[data-ui] .hint,
[data-ui] .error { margin: 0.125rem 0 0; font-size: 0.8125rem; line-height: 1.4; }
[data-ui] .hint { grid-column: 1; align-self: start; color: var(--muted); }
[data-ui] .error { grid-column: 1 / -1; margin-top: 0.375rem; color: var(--gain); font-weight: 600; }
[data-ui] .error:empty { display: none; }

/* 結果卡：頁面的視覺焦點。數字每次按鍵都更新，所以不加動畫 */
.result {
  container-type: inline-size;
  padding: clamp(1.5rem, 3vw, 2.25rem);
  background: var(--tile);
  color: var(--tile-ink);
  border-radius: var(--radius);
}

.result h2 {
  margin-bottom: 0.5rem;
  color: var(--tile-muted);
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.5;
  letter-spacing: 0;
}

[data-ui] .net {
  margin: 0;
  font-size: clamp(2rem, 11cqi, 3.25rem);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.015em;
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}
[data-ui] .net.gain { color: var(--tile-gain); }
[data-ui] .net.loss { color: var(--tile-loss); }

[data-ui] .return {
  min-height: 1.65em;
  margin: 0.375rem 0 1.25rem;
  color: var(--tile-muted);
  font-variant-numeric: tabular-nums;
}

[data-ui] dl { margin: 0; }

[data-ui] dl div {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0 1rem;
  padding-block: 0.625rem;
  border-top: 1px solid var(--tile-line);
}

[data-ui] dt { color: var(--tile-muted); }
[data-ui] dd {
  min-width: 0;
  margin: 0 0 0 auto;
  font-weight: 600;
  text-align: right;
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}
[data-ui] dl .total dt { color: var(--tile-ink); font-weight: 600; }

[data-ui] .warn {
  margin: 1rem 0 0;
  padding: 0.625rem 0.875rem;
  background: var(--tile-warn-bg);
  color: var(--tile-warn-text);
  border-radius: 0.625rem;
}

.warn {
  margin: 1rem 0 0;
  padding: 0.625rem 0.875rem;
  background: var(--warn-bg);
  color: var(--warn-text);
  border-radius: 0.625rem;
}

/* 費率：黑色章節 */
.rates {
  display: grid;
  gap: 2.5rem;
  background: var(--chapter-2);
  color: var(--tile-ink);
}

.rates-intro p { margin: 1.25rem 0 0; color: var(--tile-muted); font-size: clamp(1.0625rem, 2vw, 1.3125rem); line-height: 1.5; }

.rates .note { margin: 1.25rem 0 0; color: var(--tile-muted); font-size: 0.8125rem; }

[data-ui].table-wrap { overflow-x: auto; }

[data-ui] table { width: 100%; border-collapse: collapse; }

[data-ui] th,
[data-ui] td {
  padding: 0.875rem 1rem 0.875rem 0;
  border-bottom: 1px solid var(--tile-line);
  text-align: left;
  vertical-align: top;
}

[data-ui] thead th { color: var(--tile-muted); font-size: 0.8125rem; font-weight: 500; }
[data-ui] tbody th { font-weight: 600; white-space: nowrap; }
[data-ui] td { font-variant-numeric: tabular-nums; }
[data-ui] .date { white-space: nowrap; }

/* 怎麼算：一張卡片，四個格子 */
.how { background: var(--chapter-3); }

.how-intro { margin: 1.25rem 0 0; max-width: 38em; font-size: clamp(1.0625rem, 2vw, 1.3125rem); line-height: 1.5; }

ol.steps[data-ui] {
  display: grid;
  gap: 0.25rem;
  margin: 2.5rem 0 0;
  padding: 0;
  overflow: hidden;
  list-style: none;
  background: var(--chapter-3);
  border-radius: var(--radius);
}

ol.steps[data-ui] li { padding: 2rem clamp(1.25rem, 3vw, 2rem); background: var(--raised); font-variant-numeric: tabular-nums; }

ol.steps[data-ui] li:last-child { background: var(--tile); color: var(--tile-ink); font-weight: 600; }

.how-outro { max-width: 38em; margin: 1.5rem 0 0; }

/* 常見問題：一題一列 */
.faq { background: var(--chapter-4); }

.qa { display: grid; gap: 0.5rem; margin-top: 2.5rem; }
.qa p { margin: 0; max-width: 38em; }

.site-footer {
  padding: 3rem var(--edge) 2rem;
  background: var(--chapter-3);
  color: var(--muted);
  font-size: 0.8125rem;
}

.site-footer::before {
  content: "台股成本計算機";
  display: block;
  margin-bottom: 1.25rem;
  color: var(--ink);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.015em;
}

.site-footer nav { display: flex; flex-wrap: wrap; gap: 0.5rem 1.5rem; }
.site-footer nav a { display: inline-flex; align-items: center; min-height: 2.75rem; color: var(--muted); text-decoration: none; }
.site-footer nav a:hover { color: var(--accent); text-decoration: underline; }
.site-footer p { margin: 0.5rem 0 0; }

/* 關於、隱私權、聯絡：單欄閱讀頁 */
.content {
  max-width: calc(38em + 2 * var(--gutter));
  margin-inline: auto;
  padding: clamp(3rem, 7vw, 5.5rem) var(--gutter) clamp(4.5rem, 10vw, 7rem);
}

.content h1 { font-size: clamp(2.25rem, 6vw, 3.5rem); }
.content h2 { margin-top: 2.5rem; font-size: 1.5rem; line-height: 1.3; letter-spacing: -0.01em; }
.content p, .content ul, .content ol { margin-block: 0.75rem; }

@media (min-width: 52.5rem) {
  .tool { grid-template-columns: 1fr 1fr; }

  /* 桌面版兩張卡片等高 */
  #calc[data-ui] { display: grid; grid-auto-rows: 1fr; padding-block: 0.5rem; }
  [data-ui] .field { padding-block: 0.875rem; }

  .rates { grid-template-columns: 5fr 7fr; gap: 4rem; align-items: start; }

  ol.steps[data-ui] { grid-template-columns: 1fr 1fr; }

  .qa { grid-template-columns: 5fr 7fr; gap: 4rem; }
}

/* 窄螢幕放不下最長的交易類型，選單獨佔一列 */
@media (max-width: 24.3em) {
  [data-ui] .field:has(select) { grid-template-columns: minmax(0, 1fr); row-gap: 0.25rem; }
  [data-ui] select { grid-column: 1; }
}

/* 使用者放大字級後，寬度以 em 計算會變窄。導覽改為不固定，避免佔掉畫面；表單改上下排列，避免選單文字被截斷 */
@media (max-width: 19.95em) {
  html { scroll-padding-top: 1rem; }
  .site-header { position: static; }

  [data-ui] .field { grid-template-columns: minmax(0, 1fr); row-gap: 0.25rem; }
  [data-ui] input, [data-ui] select { grid-column: 1; }
  [data-ui] .field:has(.hint) > :is(input, select) { grid-row: auto; }
  [data-ui] select { padding-inline: 0.25rem 1.25rem; background-position: right 0.25rem center; font-size: min(0.875rem, 6.4vw); }
  [data-ui] tbody th { white-space: normal; }
  [data-ui] .net { font-size: clamp(1.5rem, 11cqi, 3.25rem); }
}

/* 只有載入與捲動進場有動畫。不依賴 JavaScript，不支援時內容直接顯示 */
@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }

  @keyframes unmask {
    from { clip-path: inset(0 0 100% 0); transform: translateY(0.35em); }
    to { clip-path: inset(-10% 0 -10% 0); transform: none; }
  }

  @keyframes rise {
    from { opacity: 0; transform: translateY(1.25rem); }
    to { opacity: 1; transform: none; }
  }

  .hero h1 { animation: unmask 700ms cubic-bezier(0.22, 1, 0.36, 1) both; }
  .lead { animation: rise 600ms 80ms cubic-bezier(0.22, 1, 0.36, 1) both; }
  .tool { animation: rise 600ms 160ms cubic-bezier(0.22, 1, 0.36, 1) both; }

  @supports (animation-timeline: view()) {
    .rates-intro, .rates-table,
    .how h2, .how-intro, .steps, .how-outro,
    .faq h2, .qa,
    .site-footer {
      animation: rise linear both;
      animation-timeline: view();
      animation-range: entry 5% entry 40%;
    }
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header {
    background: var(--chapter-3);
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
  }
}

@media (prefers-contrast: more) {
  :root { --line: currentColor; --tile-line: currentColor; --muted: currentColor; --tile-muted: currentColor; }

  .site-header {
    background: var(--chapter-3);
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
    border-bottom: 1px solid currentColor; /* taste-skill-ignore: 高對比模式要求明確邊界 */
  }

  [data-ui] input, [data-ui] select { border: 1px solid currentColor; }
}