:root {
  --page: #f6f7f9;
  --surface: #ffffff;
  --text: #182230;
  --muted: #475467;
  --primary: #166456;
  --primary-dark: #0f5146;
  --primary-soft: #e8f3f0;
  --border: #d0d5dd;
  --warning: #8a4b08;
  --warning-soft: #fff4e5;
  --danger: #b42318;
  --danger-soft: #fff0ee;
  --success: #067647;
  --shadow: 0 8px 24px rgba(16, 24, 40, 0.08);
}

* { box-sizing: border-box; }
html { min-width: 320px; }
body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.7;
}
button, input, textarea, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { cursor: pointer; }
button:disabled { cursor: not-allowed; opacity: 0.62; }
a { color: var(--primary); }
:focus-visible { outline: 3px solid #7fc7b8; outline-offset: 2px; }
.hidden { display: none !important; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.topbar {
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 20;
}
.brand { display: flex; align-items: center; gap: 12px; font-weight: 750; color: var(--text); text-decoration: none; }
.brand-mark { width: 36px; height: 36px; display: grid; place-items: center; border-radius: 10px; background: var(--primary); color: #fff; }
.top-actions { display: flex; align-items: center; gap: 10px; }
.demo-badge, .real-badge, .status-badge {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 700;
}
.demo-badge { background: var(--warning-soft); color: var(--warning); }
.real-badge { background: #ecfdf3; color: #027a48; }
.status-badge { background: var(--primary-soft); color: var(--primary-dark); }
.status-badge.danger { background: var(--danger-soft); color: var(--danger); }

.primary-button, .secondary-button, .ghost-button, .danger-button {
  min-height: 44px;
  border-radius: 9px;
  padding: 8px 16px;
  font-weight: 700;
  border: 1px solid transparent;
}
.primary-button:disabled, .secondary-button:disabled, .ghost-button:disabled, .danger-button:disabled { opacity: .55; cursor: not-allowed; }
.primary-button { background: var(--primary); color: #fff; }
.primary-button:hover { background: var(--primary-dark); }
.secondary-button { color: var(--primary-dark); background: var(--surface); border-color: var(--primary); }
.ghost-button { color: var(--text); background: transparent; border-color: var(--border); }
.danger-button { color: var(--danger); background: var(--surface); border-color: #f3b5ae; }
.icon-button { width: 44px; height: 44px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); color: var(--text); }

.notice { margin: 16px 0; padding: 12px 16px; border-radius: 9px; background: var(--warning-soft); color: #6b3a06; border: 1px solid #f5d5a6; }
.notice.error { background: var(--danger-soft); color: var(--danger); border-color: #f4c7c2; }
.notice.success { background: #ecfdf3; color: var(--success); border-color: #abefc6; }

/* Student chat */
.chat-app { min-height: 100vh; display: grid; grid-template-columns: 240px minmax(0, 1fr); }
.history-panel { background: #eef1f3; border-right: 1px solid var(--border); padding: 20px 16px; display: flex; flex-direction: column; gap: 16px; }
.history-panel h1 { font-size: 22px; margin: 0; }
.history-list { display: grid; gap: 6px; }
.history-item { width: 100%; text-align: left; border: 1px solid transparent; background: transparent; color: var(--text); padding: 10px 12px; border-radius: 8px; }
.history-item:hover, .history-item.active { background: var(--surface); border-color: var(--border); }
.history-empty { color: var(--muted); font-size: 14px; padding: 12px; }
.history-footer { margin-top: auto; display: grid; gap: 8px; }
.chat-main { min-width: 0; display: flex; flex-direction: column; min-height: 100vh; }
.chat-header { min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 12px 24px; background: var(--surface); border-bottom: 1px solid var(--border); }
.chat-header h2 { margin: 0; font-size: 20px; }
.chat-header p { margin: 0; color: var(--muted); font-size: 14px; }
.mobile-menu { display: none; }
.conversation-shell { width: min(800px, calc(100% - 32px)); margin: 0 auto; flex: 1; display: flex; flex-direction: column; }
.welcome { margin: auto 0; text-align: center; padding: 40px 0; }
.welcome h2 { margin: 0 0 8px; font-size: 28px; }
.welcome p { color: var(--muted); margin: 0 auto 22px; max-width: 580px; }
.prompt-chips { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; }
.prompt-chip { background: var(--surface); border: 1px solid var(--border); border-radius: 999px; padding: 8px 14px; color: var(--text); }
.message-list { display: grid; gap: 18px; padding: 28px 0 160px; }
.message { display: flex; gap: 10px; max-width: 90%; }
.message.user { margin-left: auto; flex-direction: row-reverse; }
.message-bubble { padding: 14px 16px; border-radius: 12px; background: var(--surface); border: 1px solid var(--border); overflow-wrap: anywhere; }
.message.user .message-bubble { background: #e9efed; border-color: #ceddd9; }
.message-meta { color: var(--muted); font-size: 12px; margin-bottom: 4px; }
.message-actions { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 9px; }
.message-actions button, .copy-code { border: 1px solid var(--border); background: var(--surface); color: var(--muted); border-radius: 7px; padding: 5px 9px; font-size: 13px; }
.code-block { margin: 12px 0; border-radius: 9px; overflow: hidden; background: #101828; color: #f2f4f7; }
.code-toolbar { display: flex; justify-content: space-between; align-items: center; padding: 7px 10px; background: #1d2939; color: #d0d5dd; font-size: 12px; }
.copy-code { color: #fff; background: transparent; border-color: #475467; }
pre { margin: 0; padding: 14px; overflow-x: auto; }
code { font-family: "Cascadia Code", Consolas, monospace; font-size: 14px; }
.composer-wrap { position: sticky; bottom: 0; padding: 12px 0 20px; background: linear-gradient(transparent, var(--page) 18%); }
.composer { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 12px; box-shadow: var(--shadow); }
.composer textarea { display: block; width: 100%; min-height: 76px; max-height: 220px; resize: vertical; border: 0; padding: 4px; color: var(--text); background: transparent; }
.composer textarea:focus { outline: none; }
.composer-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 8px; }
.composer-help { color: var(--muted); font-size: 12px; }
.course-select { min-height: 44px; max-width: 260px; border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px; background: var(--surface); }
.typing-status { color: var(--muted); padding: 12px 0; }
.settings-panel { border-top: 1px solid var(--border); padding-top: 12px; }
.settings-panel label { display: flex; gap: 9px; align-items: flex-start; margin: 8px 0; font-size: 14px; }
.settings-help { color: var(--muted); font-size: 13px; }

/* Teacher pages */
.teacher-shell { width: min(1180px, calc(100% - 40px)); margin: 28px auto 56px; }
.page-heading { display: flex; justify-content: space-between; align-items: flex-start; gap: 20px; margin-bottom: 22px; }
.page-heading h1 { margin: 0; font-size: 28px; }
.page-heading p { color: var(--muted); margin: 4px 0 0; }
.page-actions { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px; }
.filter-bar { display: flex; flex-wrap: wrap; align-items: end; gap: 12px; margin: 0 0 22px; padding: 14px 16px; background: var(--surface); border: 1px solid var(--border); border-radius: 12px; }
.filter-bar input { min-height: 38px; border: 1px solid var(--border); border-radius: 8px; padding: 5px 8px; color: var(--text); background: var(--surface); }
.filter-bar #filter-result { margin-left: auto; align-self: center; }
.login-panel, .empty-state { max-width: 620px; margin: 80px auto; padding: 28px; text-align: center; background: var(--surface); border: 1px solid var(--border); border-radius: 12px; }
.login-form { display: grid; gap: 8px; max-width: 380px; margin: 22px auto; text-align: left; }
.login-form label { font-weight: 700; }
.login-form input { width: 100%; min-height: 44px; border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px; }
.login-form button { margin-top: 8px; }
.demo-login-divider { display: flex; align-items: center; gap: 12px; margin: 24px 0 12px; color: var(--muted); font-size: 13px; }
.demo-login-divider::before, .demo-login-divider::after { content: ""; flex: 1; border-top: 1px solid var(--border); }
.summary-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin-bottom: 22px; }
.summary-card, .panel, .finding-card { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; }
.summary-card { padding: 18px; }
.summary-card strong { display: block; font-size: 30px; line-height: 1.2; margin-top: 6px; }
.summary-card span { color: var(--muted); }
.teacher-grid { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 18px; }
.panel { padding: 20px; }
.panel h2 { margin: 0 0 16px; font-size: 19px; }
.panel-heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 14px; margin-bottom: 16px; }
.panel-heading h2 { margin-bottom: 2px; }
.panel-heading p { margin: 0; }
.review-summary { margin-top: -8px; }
.review-summary .summary-card { border-top: 3px solid var(--primary); }
.segmented-control { display: inline-flex; padding: 3px; border: 1px solid var(--border); border-radius: 9px; background: var(--page); }
.segment { min-height: 36px; padding: 5px 10px; border: 0; border-radius: 6px; color: var(--muted); background: transparent; font-size: 13px; font-weight: 700; }
.segment.active { color: var(--primary-dark); background: var(--surface); box-shadow: 0 1px 3px rgba(16, 24, 40, .12); }
.filter-label { display: grid; gap: 4px; color: var(--muted); font-size: 13px; font-weight: 700; }
.filter-label select { min-height: 38px; max-width: 150px; border: 1px solid var(--border); border-radius: 8px; padding: 5px 8px; background: var(--surface); color: var(--text); }
.issue-list, .conversation-list { display: grid; gap: 10px; }
.issue-row, .conversation-row { display: grid; grid-template-columns: 1fr auto auto; gap: 14px; align-items: center; padding: 13px 0; border-bottom: 1px solid #eaecf0; }
.issue-row:last-child, .conversation-row:last-child { border-bottom: 0; }
.issue-content, .conversation-identity, .conversation-context, .conversation-states { display: grid; gap: 2px; min-width: 0; }
.conversation-row { grid-template-columns: minmax(150px, 1.1fr) minmax(150px, .9fr) minmax(175px, 1fr) auto; align-items: start; }
.conversation-context span:first-child, .conversation-identity strong { overflow-wrap: anywhere; }
.review-badge { display: inline-flex; width: fit-content; padding: 2px 8px; border-radius: 999px; font-size: 12px; font-weight: 700; background: var(--warning-soft); color: var(--warning); }
.review-confirmed, .review-revised, .review-mixed { background: #ecfdf3; color: var(--success); }
.review-rejected { background: var(--danger-soft); color: var(--danger); }
.review-not_analyzed, .review-no_findings { background: #f2f4f7; color: var(--muted); }
.small-muted { color: var(--muted); font-size: 13px; }
.link-button { color: var(--primary); background: none; border: 0; font-weight: 700; padding: 4px; text-decoration: none; }

.detail-grid { display: grid; grid-template-columns: minmax(0, 55fr) minmax(360px, 45fr); gap: 18px; align-items: start; }
.transcript { display: grid; gap: 12px; }
.transcript-message { padding: 14px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); transition: border-color .2s, box-shadow .2s; }
.transcript-message.user { border-left: 4px solid var(--primary); }
.transcript-message.assistant { border-left: 4px solid #98a2b3; }
.transcript-message.highlight { border-color: #f79009; box-shadow: 0 0 0 3px #fef0c7; }
.analysis-column { display: grid; gap: 14px; }
.finding-card { padding: 18px; }
.finding-card h3 { margin: 8px 0; font-size: 18px; }
.finding-section { margin: 14px 0; }
.finding-section strong { display: block; font-size: 13px; color: var(--muted); margin-bottom: 4px; }
.evidence-buttons { display: flex; flex-wrap: wrap; gap: 8px; }
.evidence-button { border: 1px solid var(--primary); color: var(--primary-dark); background: var(--primary-soft); border-radius: 999px; padding: 6px 10px; }
.review-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.review-form { margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border); }
.review-form label { display: block; font-weight: 700; margin: 10px 0 5px; }
.review-form textarea { width: 100%; border: 1px solid var(--border); border-radius: 8px; padding: 10px; resize: vertical; }
.review-state { margin-top: 12px; padding: 10px; border-radius: 8px; background: var(--primary-soft); }
.limitations { color: var(--muted); padding-left: 20px; }

@media (max-width: 900px) {
  .teacher-grid, .detail-grid { grid-template-columns: 1fr; }
  .summary-grid { grid-template-columns: repeat(2, 1fr); }
  .conversation-row { grid-template-columns: minmax(150px, 1fr) minmax(170px, 1fr) auto; }
  .conversation-context { grid-column: 1; }
  .conversation-states { grid-column: 2; grid-row: 1 / span 2; }
}

@media (max-width: 768px) {
  .topbar { padding: 0 14px; }
  .chat-app { display: block; }
  .history-panel { position: fixed; inset: 0 auto 0 0; width: min(86vw, 300px); z-index: 40; transform: translateX(-105%); transition: transform .2s; box-shadow: var(--shadow); }
  .history-panel.open { transform: translateX(0); }
  .mobile-menu { display: inline-grid; place-items: center; }
  .chat-header { padding: 10px 14px; }
  .conversation-shell { width: min(100% - 24px, 800px); }
  .welcome { padding: 28px 0; }
  .welcome h2 { font-size: 24px; }
  .course-select { max-width: 180px; }
  .composer-help { display: none; }
  .teacher-shell { width: min(100% - 24px, 1180px); margin-top: 18px; }
  .page-heading { flex-direction: column; }
  .page-actions { justify-content: flex-start; }
  .filter-bar #filter-result { width: 100%; margin-left: 0; }
  .summary-grid { grid-template-columns: repeat(2, 1fr); }
  .issue-row, .conversation-row { grid-template-columns: 1fr auto; }
  .issue-row .small-muted, .conversation-row .small-muted { grid-column: 1 / -1; }
  .panel-heading { flex-direction: column; }
  .conversation-context, .conversation-states { grid-column: 1; grid-row: auto; }
  .conversation-row > .link-button { grid-column: 2; grid-row: 1; }
}

@media (max-width: 430px) {
  .top-actions .ghost-button { display: none; }
  .summary-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
  .summary-card { padding: 14px; }
  .summary-card strong { font-size: 25px; }
  .panel { padding: 16px; }
  .message { max-width: 96%; }
  .composer-row { align-items: flex-end; }
  .course-select { width: 100%; max-width: none; }
}