:root {
  color-scheme: light dark;

  --bg: #f1f5f9;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --text: #0f172a;
  --muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-soft: rgba(37, 99, 235, 0.1);
  --danger: #dc2626;
  --danger-soft: rgba(220, 38, 38, 0.12);
  --success: #16a34a;
  --success-soft: rgba(22, 163, 74, 0.12);
  --ring: rgba(37, 99, 235, 0.35);
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --radius: 16px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1120;
    --surface: #111827;
    --surface-2: #0f172a;
    --border: #1e293b;
    --border-strong: #334155;
    --text: #e2e8f0;
    --muted: #94a3b8;
    --accent: #38bdf8;
    --accent-hover: #0ea5e9;
    --accent-soft: rgba(56, 189, 248, 0.14);
    --danger: #f87171;
    --danger-soft: rgba(248, 113, 113, 0.16);
    --success: #4ade80;
    --success-soft: rgba(74, 222, 128, 0.16);
    --ring: rgba(56, 189, 248, 0.45);
    --shadow: 0 16px 40px rgba(2, 6, 23, 0.5);
  }
}

* { box-sizing: border-box; }

html {
  scrollbar-gutter: stable;
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Honor OS "increase contrast" — strengthen text and borders. */
@media (prefers-contrast: more) {
  :root {
    --muted: var(--text);
    --border: var(--border-strong);
  }
  input, textarea, select, button { border: 2px solid currentColor; }
}

/* Visually hidden, still announced to assistive tech. */
.sr-only {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* Skip link: off-screen until focused. */
.skip-link {
  position: absolute;
  inset-block-start: -120%;
  inset-inline-start: 1rem;
  z-index: 1000;
  padding: 0.6rem 1.1rem;
  border-radius: 0 0 10px 10px;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  text-decoration: none;
}
.skip-link:focus-visible {
  inset-block-start: 0;
  outline: 3px solid var(--ring);
  outline-offset: 2px;
}

body {
  margin: 0;
  min-block-size: 100dvh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

/* ---------- Top bar + tabs ---------- */
.topbar {
  position: sticky;
  inset-block-start: 0;
  z-index: 10;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1rem;
  padding: 0.85rem clamp(1rem, 3vw, 2.5rem);
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: saturate(1.1) blur(8px);
  border-block-end: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 800;
  font-size: 1.1rem;
  letter-spacing: 0.01em;
}
.brand__mark {
  inline-size: 2rem;
  block-size: 2rem;
  border-radius: 9px;
  display: grid;
  place-content: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-hover));
  color: #fff;
  font-size: 1rem;
}
.brand__sub {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* Session badge button lives in the top bar, opens the popover. */
.session__badge {
  margin-inline-start: auto;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  min-block-size: auto;
  padding: 0.35rem 0.8rem;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
}
.session__badge[data-state="in"] { background: var(--success-soft); color: var(--success); }
.session__badge[data-state="out"] { background: var(--danger-soft); color: var(--danger); }
.session__badge:focus-visible { outline: none; box-shadow: 0 0 0 3px var(--ring); }

.tablist {
  inline-size: 100%;
  order: 3;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  overflow-x: auto;
  scrollbar-width: thin;
}
.tab {
  min-block-size: 44px;
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 10px;
  background: transparent;
  color: var(--muted);
  font-weight: 600;
  font-size: 0.95rem;
  white-space: nowrap;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}
.tab:hover { background: var(--surface-2); color: var(--text); }
.tab:focus-visible { outline: none; box-shadow: 0 0 0 3px var(--ring); }
.tab[aria-selected="true"] {
  background: var(--accent-soft);
  color: var(--accent);
  box-shadow: inset 0 -2px 0 0 var(--accent);
}

/* ---------- Session popover ---------- */
#session-pop {
  position: fixed;
  inset: auto 1rem auto auto;
  inset-block-start: 4.25rem;
  margin: 0;
  inline-size: min(360px, calc(100vw - 2rem));
  padding: 1.1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
}
#session-pop:popover-open {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.session-pop__title { margin: 0; font-size: 1.05rem; }

.session__facts {
  margin: 0;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.3rem 0.75rem;
  font-size: 0.85rem;
}
.session__facts dt { color: var(--muted); font-weight: 600; }
.session__facts dd { margin: 0; word-break: break-all; }

#session-pop details > summary {
  cursor: pointer;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--muted);
}
#session-pop details[open] > summary { margin-block-end: 0.5rem; }

/* ---------- Main + tab panels ---------- */
main {
  container-type: inline-size;
  inline-size: min(100%, 72rem);
  margin-inline: auto;
  padding: 2.25rem clamp(1rem, 3vw, 2.5rem) 4rem;
  min-inline-size: 0;
}
.tabpanel { animation: panel-in 0.18s ease-out; }
.tabpanel[hidden] { display: none; }
.tabpanel:focus-visible { outline: none; }

@keyframes panel-in {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

section.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem;
  margin-block-end: 1.1rem;
  box-shadow: var(--shadow);
}
section.card > h3 { margin: 0 0 0.4rem; font-size: 1.15rem; }
section.card > p { margin: 0 0 1rem; color: var(--muted); font-size: 0.92rem; }

.subhead {
  margin: 1.25rem 0 0.6rem;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--muted);
}

.field { margin-block-end: 0.9rem; }
.field label {
  display: block;
  margin-block-end: 0.35rem;
  font-weight: 600;
  font-size: 0.92rem;
}

/* Two-column field grid that collapses on narrow containers. */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 1rem;
}
@container (max-width: 520px) {
  .grid-2 { grid-template-columns: minmax(0, 1fr); }
}

input, textarea, select {
  inline-size: 100%;
  min-block-size: 44px;
  padding: 0.6rem 0.75rem;
  border-radius: 10px;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  font-size: 1rem;
  color: inherit;
  font-family: inherit;
}
textarea { min-block-size: 4rem; resize: vertical; }

input:focus-visible, textarea:focus-visible, select:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--ring);
}

/* Validation feedback only after the user has interacted. */
input:user-invalid, textarea:user-invalid {
  border-color: var(--danger);
}
input:user-invalid:focus-visible, textarea:user-invalid:focus-visible {
  box-shadow: 0 0 0 3px var(--danger-soft);
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: center;
}

button {
  appearance: none;
  border: none;
  border-radius: 999px;
  min-block-size: 44px;
  padding: 0.6rem 1.3rem;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: background 0.15s ease, transform 0.1s ease;
}
button:disabled { background: var(--border-strong); cursor: progress; }
button:not(:disabled):hover { background: var(--accent-hover); }
button:not(:disabled):active { transform: scale(0.97); }
button:focus-visible { outline: none; box-shadow: 0 0 0 3px var(--ring); }

button.btn-ghost {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--border-strong);
}
button.btn-ghost:not(:disabled):hover { background: var(--accent-soft); }
button.btn-danger { background: var(--danger); }
button.btn-danger:not(:disabled):hover { filter: brightness(0.92); }

.status {
  min-block-size: 1.2rem;
  margin-block-start: 0.75rem;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--muted);
}
.status--error { color: var(--danger); }

.result {
  margin-block-start: 0.75rem;
  max-block-size: 18rem;
  overflow: auto;
  overscroll-behavior: contain;
  white-space: pre-wrap;
  word-break: break-word;
}
.result:empty { display: none; }

pre {
  background: #0f172a;
  color: #e2e8f0;
  border-radius: 12px;
  padding: 1rem;
  overflow-x: auto;
  font-size: 0.85rem;
  margin: 0;
}
@media (prefers-color-scheme: dark) {
  pre { background: #020617; color: #cbd5f5; }
}

/* ---------- Wine reference table ---------- */
.wine-result {
  margin-block-start: 0.75rem;
  max-block-size: 22rem;
  overflow: auto;
  overscroll-behavior: contain;
  scrollbar-gutter: stable;
}
.wine-result:empty { display: none; }
.wine-summary {
  margin: 0 0 0.6rem;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--muted);
}
.wine-empty { margin: 0; color: var(--muted); }

.wine-table {
  inline-size: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
.wine-table th, .wine-table td {
  text-align: start;
  padding: 0.5rem 0.65rem;
  border-block-end: 1px solid var(--border);
  vertical-align: top;
}
.wine-table thead th {
  position: sticky;
  inset-block-start: 0;
  background: var(--surface-2);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}
.wine-table tbody tr:hover { background: var(--surface-2); }
.wine-table .cell-name { font-weight: 600; }

.code-chip,
.cell-id code {
  font-family: ui-monospace, "Cascadia Code", Menlo, Consolas, monospace;
  font-size: 0.78rem;
}
.code-chip {
  padding: 0.1rem 0.45rem;
  border-radius: 6px;
  background: var(--accent-soft);
  color: var(--accent);
}

.cell-chips { display: flex; flex-wrap: wrap; gap: 0.3rem; }
.chip {
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 0.78rem;
}

.cell-id { white-space: nowrap; }
.cell-id code { color: var(--muted); }
.copy-btn {
  min-block-size: auto;
  margin-inline-start: 0.5rem;
  padding: 0.2rem 0.55rem;
  border-radius: 8px;
  background: transparent;
  border: 1px solid var(--border-strong);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
}
.copy-btn:not(:disabled):hover { background: var(--accent-soft); }
.copy-btn:focus-visible { outline: none; box-shadow: 0 0 0 3px var(--ring); }
.copy-btn.is-copied { color: var(--success); border-color: var(--success); }

/* ---------- Region tree (parent/child) ---------- */
.tree { font-size: 0.9rem; }
.tree summary { list-style: none; }
.tree summary::-webkit-details-marker { display: none; }

.tree-row {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.35rem 0.4rem;
  border-radius: 8px;
}
.tree-row:hover { background: var(--surface-2); }
summary.tree-row { cursor: pointer; }
summary.tree-row:focus-visible { outline: none; box-shadow: 0 0 0 3px var(--ring); }

.tree-name { font-weight: 600; }

.tw {
  flex: 0 0 auto;
  inline-size: 1rem;
  text-align: center;
  color: var(--muted);
  transition: transform 0.15s ease;
}
details[open] > summary .tw { transform: rotate(90deg); }
.tw--leaf { visibility: hidden; }

.tree-count {
  flex: 0 0 auto;
  padding: 0 0.4rem;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.72rem;
}

/* ID をツリー行の右端へ寄せて縦に揃える。 */
.tree-row .cell-id { margin-inline-start: auto; }

/* 子要素はインデント + ガイド線で階層を可視化。 */
.tree-children {
  margin-inline-start: 0.9rem;
  padding-inline-start: 0.6rem;
  border-inline-start: 1px solid var(--border);
}

.email-list { margin: 0.75rem 0 0; padding-inline-start: 1.25rem; }
.email-list:empty { display: none; }
.email-list li { margin: 0.25rem 0; word-break: break-all; }

img.preview {
  display: block;
  max-inline-size: 160px;
  max-block-size: 160px;
  border-radius: 12px;
  object-fit: cover;
}
img[hidden] { display: none; }

.profile-result {
  margin-block-start: 1rem;
  padding-block-start: 1rem;
  border-block-start: 1px solid var(--border);
}
.profile-result p { margin: 0.35rem 0 0; font-size: 0.9rem; }

/* ---------- Toasts (popover, top layer) ---------- */
#toast-region {
  position: fixed;
  inset: auto 1rem 1rem auto;
  margin: 0;
  padding: 0;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column-reverse;
  gap: 0.6rem;
  max-inline-size: min(360px, calc(100vw - 2rem));
  overflow: visible;
}
#toast-region:popover-open { display: flex; }
.toast {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  padding: 0.75rem 0.9rem;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-inline-start: 4px solid var(--success);
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.25);
  font-size: 0.9rem;
  color: var(--text);
}
.toast--error { border-inline-start-color: var(--danger); }
.toast span { flex: 1 1 auto; word-break: break-word; }
.toast__close {
  flex: 0 0 auto;
  padding: 0;
  inline-size: 1.5rem;
  block-size: 1.5rem;
  min-block-size: auto;
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
}
.toast__close:not(:disabled):hover { background: var(--surface-2); }

/* ---------- Card header (title + actions) ---------- */
.card-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  margin-block-end: 0.5rem;
}
.card-head h3 { margin: 0; }

/* ---------- Event dialog ---------- */
.dialog {
  inline-size: min(680px, calc(100vw - 2rem));
  max-block-size: calc(100dvh - 4rem);
  padding: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
}
.dialog[open] { display: flex; flex-direction: column; }
.dialog::backdrop { background: rgba(15, 23, 42, 0.5); }
.dialog__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin: 0;
  padding: 1rem 1.25rem;
  border-block-end: 1px solid var(--border);
}
.dialog__head h3 { margin: 0; font-size: 1.15rem; }
.dialog__close {
  flex: 0 0 auto;
  min-block-size: auto;
  inline-size: 2rem;
  block-size: 2rem;
  padding: 0;
  border-radius: 8px;
  border: 1px solid var(--border-strong);
  background: transparent;
  color: var(--muted);
  font-size: 1.25rem;
  line-height: 1;
}
.dialog__close:not(:disabled):hover { background: var(--surface-2); color: var(--text); }
.dialog__body {
  min-block-size: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 1.25rem;
}

/* ---------- Event list + cards ---------- */
.events-list { display: flex; flex-direction: column; gap: 0.9rem; }
.events-list:empty { display: none; }

.event-card {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-2);
  padding: 1rem;
}
.event-detail { margin-block-start: 0.75rem; }

.event-card__head {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.6rem;
}
.event-card__title { margin: 0; font-size: 1.05rem; flex: 1 1 auto; }
.event-card__body {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  line-clamp: 3;
  overflow: clip;
}

.event-meta {
  margin: 0.75rem 0 0;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.25rem 0.75rem;
  font-size: 0.85rem;
}
.event-meta dt { color: var(--muted); font-weight: 600; }
.event-meta dd { margin: 0; word-break: break-word; }

.event-card__foot {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-block-start: 0.85rem;
  padding-block-start: 0.75rem;
  border-block-start: 1px solid var(--border);
}
.event-card__actions {
  margin-inline-start: auto;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.event-card__actions button {
  min-block-size: auto;
  padding: 0.4rem 0.9rem;
}
.join-status {
  margin: 0.5rem 0 0;
  min-block-size: 1.1rem;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--success);
}
.join-status.is-error { color: var(--danger); }
.join-status:empty { display: none; }

/* セクション区切りラベル（イベントページ内の「問題・正解・回答」など） */
.group-label {
  margin: 1.75rem 0 0.85rem;
  padding-block-end: 0.5rem;
  border-block-end: 1px solid var(--border);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.vis-badge {
  flex: 0 0 auto;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
}
.vis-public { background: var(--success-soft); color: var(--success); }
.vis-unlisted { background: var(--accent-soft); color: var(--accent); }
.vis-private { background: var(--danger-soft); color: var(--danger); }