/* 登入／註冊頁：與遊戲同一套方格作業簿風格 */
:root {
  --paper: #f2f5f7;
  --grid: #dde5eb;
  --card: #ffffff;
  --ink: #1c2733;
  --muted: #5b6b7a;
  --line: #c9d4dd;
  --hl: #ffd84a;
  --hl-ink: #1c2733;
  --hl-mark: #ffd84a;
  --neg: #2554c7;
  --pos: #c25a14;
  --bad: #c8323c;
  --font-display: "Huninn", "Noto Sans TC", "PingFang TC", sans-serif;
  --font-body: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --paper: #0f1720;
    --grid: #1a2632;
    --card: #16212c;
    --ink: #e4ecf3;
    --muted: #93a4b4;
    --line: #2b3a48;
    --hl: #e9c53f;
    --hl-mark: rgba(233, 197, 63, 0.32);
    --neg: #86a8ff;
    --pos: #f4a261;
    --bad: #f07178;
  }
}
* { box-sizing: border-box; }
html, body { min-height: 100%; }
body {
  margin: 0;
  background-color: var(--paper);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  display: grid;
  place-items: center;
  padding: 32px 16px;
}
main { width: 100%; max-width: 420px; display: grid; gap: 18px; }
.brand { display: grid; gap: 4px; }
.eyebrow { margin: 0; color: var(--muted); font-size: 0.85rem; letter-spacing: 0.08em; }
h1 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 400;
  font-size: 2.2rem;
  justify-self: start;
  background: linear-gradient(transparent 58%, var(--hl-mark) 58%, var(--hl-mark) 92%, transparent 92%);
  padding-inline: 4px;
}
.numbers { font-weight: 800; letter-spacing: 0.08em; }
.numbers .n { color: var(--neg); }
.numbers .p { color: var(--pos); }
form {
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: 14px;
  padding: 22px;
  display: grid;
  gap: 14px;
}
.field { display: grid; gap: 4px; }
label { font-weight: 700; font-size: 0.95rem; }
.hint { color: var(--muted); font-size: 0.8rem; }
input {
  font: inherit;
  padding: 0.6rem 0.8rem;
  border-radius: 10px;
  border: 2px solid var(--line);
  background: var(--paper);
  color: var(--ink);
}
input:focus-visible { outline: none; border-color: var(--ink); box-shadow: 0 0 0 3px var(--hl); }
button {
  font: inherit;
  font-weight: 700;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  border: none;
  background: var(--ink);
  color: var(--paper);
  cursor: pointer;
}
button:hover { box-shadow: 0 0 0 4px var(--hl); }
button:disabled { opacity: 0.5; cursor: wait; }
.error:empty { display: none; }
.error { margin: 0; color: var(--bad); font-weight: 700; }
.switch { text-align: center; color: var(--muted); margin: 0; }
.switch a { color: var(--ink); font-weight: 700; }