:root {
  --ink: #123566;
  --muted: #4a6381;
  --blue: #248df2;
  --btn: #1b64c4;
  --btn-dark: #14509f;
  --blue-soft: #eaf6ff;
  --blue-pale: #f5fbff;
  --yellow: #ffd441;
  --yellow-soft: #fff6ca;
  --warn-ink: #5a4200;
  --warn-line: #b58900;
  --green: #0f7a55;
  --green-soft: #e6fbf2;
  --red: #b3261e;
  --red-soft: #fdecea;
  --white: #fff;
  --line: #c9dcec;
  --shadow: 0 6px 20px rgba(18, 53, 102, .08);
  --radius: 16px;
  font-family: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", system-ui, -apple-system, sans-serif;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; color: var(--ink); background: var(--blue-pale);
  font-size: 16px; line-height: 1.6; min-height: 100vh;
  overflow-x: hidden;
}
h1, h2, h3, h4, p, ul { margin: 0; }
ul { padding-left: 1.2em; }
button, input, select { font: inherit; color: inherit; }
button { cursor: pointer; }
svg.icon { width: 1.25em; height: 1.25em; flex: none; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }

.sr-only, .sr-offscreen {
  position: absolute !important; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

:focus-visible { outline: 3px solid #0b3d91; outline-offset: 2px; border-radius: 6px; }
[tabindex="-1"]:focus { outline: none; }
h1[tabindex="-1"]:focus-visible, h2[tabindex="-1"]:focus-visible { outline: 3px solid #0b3d91; }

.topbar {
  position: sticky; top: 0; z-index: 5; display: flex; align-items: center; justify-content: space-between;
  gap: 8px; padding: 10px 16px; background: rgba(255, 255, 255, .96); border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; }
.brand-mark {
  display: grid; place-items: center; width: 32px; height: 32px; border-radius: 10px;
  background: var(--btn); color: #fff; font-weight: 800;
}
.dev-tag { font-size: 12px; font-weight: 700; padding: 2px 8px; border-radius: 999px; background: var(--yellow-soft); color: var(--warn-ink); border: 1px solid var(--warn-line); }

main { max-width: 560px; margin: 0 auto; padding: 16px 16px 48px; }
.view > * + * { margin-top: 16px; }
h1 { font-size: 24px; line-height: 1.35; }
h2 { font-size: 18px; line-height: 1.4; }
.lead { color: var(--muted); }
.small { font-size: 14px; color: var(--muted); }
.eyebrow { font-size: 13px; font-weight: 700; color: var(--btn); letter-spacing: .04em; }

.card {
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; box-shadow: var(--shadow);
}
.card > * + * { margin-top: 12px; }
.card-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.card-head h2 { overflow-wrap: anywhere; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 48px;
  padding: 10px 18px; border-radius: 14px; border: 2px solid transparent; font-weight: 700;
  text-align: center; line-height: 1.3; background: var(--white);
}
.btn[disabled] { opacity: .6; cursor: not-allowed; }
.btn-primary { background: var(--btn); color: #fff; }
.btn-primary:not([disabled]):hover { background: var(--btn-dark); }
.btn-secondary { border-color: var(--btn); color: var(--btn); background: var(--white); }
.btn-ghost { color: var(--btn); background: transparent; border-color: transparent; text-decoration: underline; text-underline-offset: 3px; }
.btn-danger { background: var(--red); color: #fff; }
.btn-danger-outline { border-color: var(--red); color: var(--red); background: var(--white); }
.btn-block { width: 100%; }
.btn-small { min-height: 44px; padding: 6px 14px; font-size: 15px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; }
.btn-row > .btn { flex: 1 1 140px; }

.back { display: inline-flex; align-items: center; gap: 4px; min-height: 44px; padding: 0 8px 0 0; border: 0; background: none; color: var(--btn); font-weight: 700; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { display: inline-flex; align-items: center; gap: 6px; padding: 4px 12px; border-radius: 999px; background: var(--blue-soft); border: 1px solid var(--line); font-size: 14px; font-weight: 600; }
.chip.on { background: var(--green-soft); border-color: var(--green); color: var(--green); }

.banner { display: flex; gap: 12px; padding: 12px 14px; border-radius: 14px; border: 2px solid; align-items: flex-start; }
.banner .icon { margin-top: 3px; }
.banner strong { display: block; }
.banner-warn { background: var(--yellow-soft); border-color: var(--warn-line); color: var(--warn-ink); }
.banner-danger { background: var(--red-soft); border-color: var(--red); color: #6e140f; }
.banner-info { background: var(--blue-soft); border-color: var(--line); }
.banner-ok { background: var(--green-soft); border-color: var(--green); color: #0a4d36; }

.field { display: block; }
.field > label, .field > legend, legend.label { display: block; font-weight: 700; margin-bottom: 6px; padding: 0; }
.field .hint { font-size: 14px; color: var(--muted); margin-top: 4px; }
.field + .field, .field + .btn, .field + .banner { margin-top: 16px; }
fieldset.field { border: 0; margin: 0; padding: 0; min-width: 0; }
input[type=text], select {
  width: 100%; min-height: 48px; padding: 10px 12px; font-size: 16px; border: 2px solid #7f98b3;
  border-radius: 12px; background: #fff;
}
input[aria-invalid=true], select[aria-invalid=true] { border-color: var(--red); background: var(--red-soft); }
.field-error { display: flex; gap: 6px; align-items: flex-start; margin-top: 6px; color: var(--red); font-weight: 700; font-size: 15px; }
.field-error[hidden], .form-error[hidden] { display: none; }
.form-error { display: flex; gap: 8px; align-items: flex-start; margin-top: 12px; padding: 10px 12px; border-radius: 12px; border: 2px solid var(--red); background: var(--red-soft); color: #6e140f; font-weight: 600; }

.segments { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.segments input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.segments label {
  display: flex; align-items: center; justify-content: center; min-height: 48px; text-align: center; padding: 6px;
  border: 2px solid #7f98b3; border-radius: 12px; font-weight: 700; margin: 0; background: #fff; cursor: pointer; line-height: 1.25;
}
.segments input:checked + label { background: var(--btn); border-color: var(--btn); color: #fff; }
.segments input:focus-visible + label { outline: 3px solid #0b3d91; outline-offset: 2px; }
.segments input:checked + label::before { content: "✓ "; }

.check { display: flex; gap: 12px; align-items: flex-start; padding: 10px 0; }
.check input { flex: none; width: 24px; height: 24px; margin: 2px 0 0; accent-color: var(--btn); }
.check label { font-weight: 600; min-height: 44px; display: flex; align-items: center; flex: 1; }

.doc { max-height: 38vh; overflow: auto; padding: 12px 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--blue-pale); font-size: 15px; }
.doc > * + * { margin-top: 8px; }
.doc h4 { font-size: 16px; }

.list { list-style: none; padding: 0; }
.list > li + li { border-top: 1px solid var(--line); }
.list-item { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 12px 0; }
.list-item .grow { min-width: 0; overflow-wrap: anywhere; }
.list-item b { display: block; }

.link-list { list-style: none; padding: 0; display: grid; gap: 10px; }
.link-btn { display: flex; width: 100%; align-items: center; gap: 12px; min-height: 52px; padding: 10px 14px; border: 1px solid var(--line); border-radius: 14px; background: #fff; text-align: left; font-weight: 700; }
.link-btn .chev { margin-left: auto; color: var(--muted); }

.switch-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.switch {
  display: inline-flex; align-items: center; gap: 10px; min-height: 48px; padding: 6px 14px 6px 8px; border-radius: 999px;
  border: 2px solid #7f98b3; background: #fff; font-weight: 700;
}
.switch .knob { width: 28px; height: 28px; border-radius: 50%; background: #7f98b3; display: grid; place-items: center; color: #fff; }
.switch[aria-checked=true] { border-color: var(--green); color: var(--green); background: var(--green-soft); }
.switch[aria-checked=true] .knob { background: var(--green); }
.switch[disabled] { opacity: .6; }

.code-box { text-align: center; padding: 18px 8px; border-radius: 16px; background: var(--blue-soft); border: 2px dashed var(--btn); }
.code { display: block; font-family: ui-monospace, "SFMono-Regular", Consolas, monospace; font-size: 38px; font-weight: 800; letter-spacing: .06em; line-height: 1.2; word-break: keep-all; }
.code.expired { color: #6b7f96; text-decoration: line-through; }
.timer { display: inline-flex; align-items: center; gap: 6px; font-weight: 700; margin-top: 8px; }

dialog.modal {
  width: min(520px, calc(100vw - 24px)); max-height: calc(100vh - 24px); overflow: auto; padding: 18px 16px;
  border: 0; border-radius: 20px; color: var(--ink); background: #fff; box-shadow: 0 20px 60px rgba(0, 20, 60, .35);
}
dialog.modal::backdrop { background: rgba(18, 53, 102, .55); }
.modal-body { margin-top: 12px; }
.modal-body > * + * { margin-top: 14px; }
dialog.modal h2 { overflow-wrap: anywhere; }

.center-state { display: grid; justify-items: center; gap: 14px; padding: 64px 0; text-align: center; }
.center-state p { max-width: 30em; }
.spinner { width: 36px; height: 36px; border-radius: 50%; border: 4px solid var(--line); border-top-color: var(--btn); animation: spin 1s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .spinner { animation-duration: 3s; } * { scroll-behavior: auto !important; } }

.toasts { position: fixed; left: 12px; right: 12px; bottom: calc(12px + env(safe-area-inset-bottom)); z-index: 20; display: grid; gap: 8px; pointer-events: none; max-width: 536px; margin: 0 auto; }
.toast { display: flex; gap: 10px; align-items: flex-start; padding: 12px 14px; border-radius: 14px; background: #0f2a52; color: #fff; font-weight: 600; box-shadow: var(--shadow); pointer-events: auto; }
.toast.error { background: #7a1712; }
.toast .icon { margin-top: 3px; }

.status-tag { display: inline-flex; align-items: center; gap: 4px; padding: 2px 10px; border-radius: 999px; font-size: 14px; font-weight: 700; border: 1px solid; }
.status-tag.ok { color: var(--green); background: var(--green-soft); border-color: var(--green); }
.status-tag.off { color: #5a2a26; background: var(--red-soft); border-color: var(--red); }

.noscript { padding: 16px; }
.dev-tag[hidden] { display: none; }

@media (max-width: 360px) {
  .code { font-size: 32px; }
  main { padding-left: 12px; padding-right: 12px; }
}
@media (prefers-color-scheme: dark) {
  /* 家長端暫只提供淺色主題，避免在 LINE 內建瀏覽器對比不一致 */
  :root { color-scheme: light; }
}

li { overflow-wrap: anywhere; }
ol { margin: 0; padding-left: 1.4em; }
.modal-body > div > * + * { margin-top: 14px; }