:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --border: #e2e5ea;
  --text: #1f2430;
  --muted: #6b7280;
  --brand: #3454d1;
  --brand-dark: #26399c;
  --danger: #d64545;
  --sidebar-bg: #1b2233;
  --sidebar-text: #cbd3e6;
  --sidebar-active: #3454d1;
  --radius: 10px;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
}

/* ---------- Auth (login) ---------- */
.auth-shell { background: linear-gradient(135deg, #1b2233, #3454d1); min-height: 100vh; }
.auth-wrap { min-height: 100vh; display: flex; align-items: center; justify-content: center; padding: 24px; }
.auth-card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 40px;
  width: 100%;
  max-width: 380px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.25);
}
.auth-brand { display: flex; align-items: center; gap: 10px; font-size: 22px; font-weight: 700; margin-bottom: 4px; }
.auth-subtitle { color: var(--muted); margin: 0 0 24px; font-size: 14px; }
.auth-form { display: flex; flex-direction: column; gap: 6px; }
.auth-form label { font-size: 13px; font-weight: 600; margin-top: 10px; }
.auth-form input {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
}
.auth-form input:focus { outline: 2px solid var(--brand); border-color: var(--brand); }

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: var(--brand);
  color: #fff;
  font-weight: 700;
}

/* ---------- Buttons / alerts ---------- */
.btn {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  padding: 9px 16px;
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
}
.btn:hover { background: #f0f1f5; }
.btn-primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); }
.btn-danger { color: var(--danger); }
.btn-danger:hover { background: #fdecec; }
.btn-block { width: 100%; margin-top: 18px; }
.btn-small { padding: 6px 10px; font-size: 13px; }

.alert { padding: 10px 14px; border-radius: 8px; font-size: 14px; margin-bottom: 16px; }
.alert-error { background: #fdecec; color: var(--danger); border: 1px solid #f5b8b8; }
.alert-success { background: #e6f6ea; color: #237a3f; border: 1px solid #b8e6c4; }

/* ---------- App shell / sidebar ---------- */
.layout { display: flex; min-height: 100vh; }
.sidebar {
  width: 240px;
  flex-shrink: 0;
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  transition: width 0.2s ease, transform 0.2s ease;
}
.sidebar-brand { display: flex; align-items: center; gap: 10px; padding: 20px 18px; font-weight: 700; font-size: 17px; color: #fff; }
.sidebar-nav { flex: 1; padding: 8px 10px; overflow-y: auto; }
.nav-group { margin-bottom: 4px; }
.nav-group-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: none;
  border: none;
  color: var(--sidebar-text);
  padding: 10px 12px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-weight: 700;
  cursor: pointer;
  border-radius: 6px;
}
.nav-group-toggle:hover { background: rgba(255,255,255,0.06); }
.chevron { transition: transform 0.15s ease; font-size: 11px; }
.nav-group.collapsed .chevron { transform: rotate(-90deg); }
.nav-submenu { display: flex; flex-direction: column; overflow: hidden; }
.nav-group.collapsed .nav-submenu { display: none; }
.nav-link {
  color: var(--sidebar-text);
  text-decoration: none;
  padding: 9px 16px 9px 26px;
  font-size: 14px;
  border-radius: 6px;
  margin: 1px 4px;
}
.nav-link:hover { background: rgba(255,255,255,0.08); color: #fff; }
.nav-link.active { background: var(--sidebar-active); color: #fff; font-weight: 600; }

.sidebar-footer { padding: 14px; border-top: 1px solid rgba(255,255,255,0.08); }
.user-chip { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.user-avatar {
  width: 32px; height: 32px; border-radius: 50%;
  background: var(--brand); color: #fff;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 14px;
}
.user-meta { display: flex; flex-direction: column; line-height: 1.2; }
.user-name { font-size: 13px; font-weight: 600; color: #fff; }
.user-role { font-size: 11px; text-transform: uppercase; color: var(--sidebar-text); }
.logout-btn {
  width: 100%;
  background: rgba(255,255,255,0.08);
  color: #fff; border: none; padding: 8px; border-radius: 6px; cursor: pointer; font-size: 13px;
}
.logout-btn:hover { background: rgba(255,255,255,0.16); }

/* Collapsed (icon-only) sidebar */
.sidebar.collapsed { width: 64px; }
.sidebar.collapsed .brand-text,
.sidebar.collapsed .nav-group-label,
.sidebar.collapsed .chevron,
.sidebar.collapsed .nav-submenu,
.sidebar.collapsed .user-meta,
.sidebar.collapsed .logout-btn span,
.sidebar.collapsed .sidebar-footer form { display: none; }
.sidebar.collapsed .sidebar-footer { display: flex; justify-content: center; }
.sidebar.collapsed .user-chip { margin-bottom: 0; }

.main-col { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.topbar {
  display: flex; align-items: center; gap: 14px;
  padding: 16px 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.sidebar-toggle { background: none; border: none; font-size: 20px; cursor: pointer; color: var(--text); }
.page-title { font-size: 18px; margin: 0; }
.content { padding: 24px; flex: 1; }

/* ---------- Questions page ---------- */
.toolbar-actions { display: flex; align-items: center; gap: 12px; }
.hide-attempted-control { display: inline-flex; align-items: center; gap: 6px; color: var(--text); font-size: 13px; white-space: nowrap; cursor: pointer; }
.hide-attempted-control input { accent-color: var(--brand); }
.session-student-trigger {
  position: relative; display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; padding: 0; border: 1px solid var(--border); border-radius: 9px;
  color: var(--brand); background: var(--surface); cursor: pointer;
}
.session-student-trigger:hover { background: #eef1fb; border-color: var(--brand); }
.session-student-trigger svg { width: 22px; height: 22px; fill: currentColor; }
.session-student-count {
  position: absolute; top: -6px; right: -6px; min-width: 18px; height: 18px; padding: 0 4px;
  display: flex; align-items: center; justify-content: center; border-radius: 10px;
  background: var(--danger); color: #fff; border: 2px solid var(--surface); font-size: 10px; font-weight: 700;
}
.session-student-heading { display: flex; justify-content: space-between; align-items: center; gap: 14px; }
.session-student-heading div { display: flex; flex-direction: column; gap: 2px; }
.session-student-heading span { color: var(--muted); font-size: 12px; }
.session-student-heading .panel-title { margin-bottom: 0; }
.modal-close { border: 0; background: transparent; color: var(--muted); font-size: 28px; line-height: 1; cursor: pointer; }
.session-student-modal { max-height: min(680px, 88vh); overflow: hidden; }
.session-student-list { display: flex; flex-wrap: wrap; gap: 8px 14px; margin-top: 18px; max-height: 52vh; overflow-y: auto; padding: 2px; }
.session-student-choice { display: inline-flex; align-items: center; gap: 6px; font-size: 13px; cursor: pointer; }
.session-student-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 20px; }
.student-color-dot {
  display: inline-block; flex: 0 0 auto; width: 10px; height: 10px; border-radius: 50%;
  background: var(--student-color); box-shadow: 0 0 0 1px rgba(0,0,0,0.14);
}
.toolbar { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 18px; }
.search-input {
  flex: 1; max-width: 420px;
  padding: 10px 14px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px;
}
.result-count { color: var(--muted); font-size: 13px; white-space: nowrap; }

.question-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 18px;
}
.q-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.q-card[hidden] { display: none; }
.q-card-image-btn {
  border: none; padding: 0; margin: 0; background: #f8f9fb; cursor: pointer;
  display: block; width: 100%; position: relative; text-decoration: none;
}
.q-card-image {
  width: 100%;
  display: block;
  height: 120px;
  object-fit: cover;
  object-position: top;
}
.q-card-expand-hint {
  position: absolute; right: 8px; bottom: 8px;
  background: rgba(27,34,51,0.75); color: #fff;
  font-size: 11px; padding: 3px 8px; border-radius: 5px;
}
.q-card-body { padding: 12px 14px 14px; display: flex; flex-direction: column; gap: 6px; }
.q-card-filename-row { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.q-card-filename { font-weight: 600; font-size: 14px; }
.question-attempt-dots { display: flex; align-items: center; flex-wrap: wrap; justify-content: flex-end; gap: 5px; }
.q-card-topic { font-size: 13px; color: var(--muted); }
.q-card-meta { font-size: 12px; color: var(--muted); }
.q-card-tags { display: flex; flex-wrap: wrap; gap: 6px; }
.tag {
  background: #eef1fb; color: var(--brand-dark);
  font-size: 11px; padding: 3px 8px; border-radius: 20px; font-weight: 600;
}
.tag-review-badge { display: inline-block; margin-top: 5px; padding: 3px 8px; border-radius: 20px; background: #fff0cc; color: #8a5900; font-size: 11px; font-weight: 700; }
.q-card-solution { font-size: 12px; color: var(--brand); text-decoration: none; margin-top: 2px; }
.q-card-solution:hover { text-decoration: underline; }

.q-card-stats { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 2px; }
.stat-pill {
  background: #eef8f0; color: #237a3f;
  font-size: 11px; padding: 3px 8px; border-radius: 20px; font-weight: 600;
}
.stat-pill-muted { background: #eef0f3; color: var(--muted); }

.admin-panel { margin-top: 6px; border-top: 1px dashed var(--border); padding-top: 8px; }
.admin-panel + .admin-panel { margin-top: 4px; }
.admin-panel summary { cursor: pointer; font-size: 12px; font-weight: 600; color: var(--brand); }
.record-panel summary { color: #237a3f; }
.badge-warning {
  background: #fdf3d8; color: #92650a; border: 1px solid #f2dd9e;
  font-size: 11px; padding: 4px 8px; border-radius: 6px; margin-top: 8px;
}
.inline-edit-form { display: flex; flex-direction: column; gap: 4px; margin-top: 10px; }
.inline-edit-form label { font-size: 11px; font-weight: 600; color: var(--muted); }
.inline-edit-form input[type="text"],
.inline-edit-form input[type="number"],
.inline-edit-form input[type="datetime-local"],
.inline-edit-form select,
.inline-edit-form textarea {
  padding: 6px 8px; border: 1px solid var(--border); border-radius: 6px; font-size: 12px; font-family: inherit;
}
.inline-edit-form textarea { resize: vertical; }
.inline-edit-form .btn { align-self: flex-start; margin-top: 4px; }
.score-part-row { display: flex; align-items: center; gap: 6px; }
.score-part-row input[type="number"] { width: 70px; }
.score-part-label { font-size: 12px; color: var(--text); white-space: nowrap; }
.record-score-link { display: inline-block; align-self: flex-start; margin-top: 6px; text-decoration: none; }

/* ---------- Dedicated score window ---------- */
.record-window-header { display: flex; justify-content: space-between; align-items: center; gap: 16px; margin-bottom: 18px; }
.source-pdf-actions { display: flex; align-items: center; justify-content: flex-end; gap: 8px; flex-wrap: wrap; }
.source-unavailable { color: var(--muted); font-size: 13px; }
.tab-list { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 20px; overflow-x: auto; }
.tab-button { border: 0; background: transparent; padding: 11px 16px; color: var(--muted); font: inherit; font-size: 14px; cursor: pointer; border-bottom: 3px solid transparent; white-space: nowrap; }
.tab-button.active { color: var(--brand); border-bottom-color: var(--brand); font-weight: 700; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }
.image-tab { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; text-align: center; }
.image-edit-panel { text-align: left; }
.image-tab-actions { display: flex; justify-content: flex-end; margin-bottom: 12px; }
.image-tab img { display: block; max-width: 100%; height: auto; margin: auto; }
.student-picker-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 9px; margin-bottom: 18px; }
.student-filter-bar { display: grid; grid-template-columns: minmax(220px, 2fr) minmax(150px, 1fr) auto; gap: 12px; align-items: end; margin-bottom: 16px; }
.student-filter-bar .field span { font-size: 12px; font-weight: 600; color: var(--muted); }
.student-filter-bar input, .student-filter-bar select { padding: 9px 11px; border: 1px solid var(--border); border-radius: 7px; font: inherit; font-size: 14px; background: #fff; }
.student-match-count { color: var(--muted); font-size: 13px; padding-bottom: 10px; white-space: nowrap; }
.student-choice { display: flex; gap: 9px; align-items: center; border: 1px solid var(--border); border-radius: 8px; padding: 10px; cursor: pointer; }
.student-choice[hidden] { display: none; }
.student-choice:has(input:checked) { border-color: var(--brand); background: #eef1fb; }
.student-choice small { display: block; color: var(--muted); margin-top: 2px; }
.score-date { max-width: 280px; margin-bottom: 16px; }
.student-score-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; margin: 0 0 14px; }
.student-score-card legend { padding: 0 7px; font-weight: 700; color: var(--brand-dark); }
.score-fields { display: flex; gap: 14px; flex-wrap: wrap; }
.score-fields label, .student-remarks { display: flex; flex-direction: column; gap: 5px; font-size: 12px; font-weight: 600; color: var(--muted); }
.score-fields input, .student-remarks textarea, .score-date input { padding: 8px; border: 1px solid var(--border); border-radius: 6px; font: inherit; }
.score-fields input[type="number"] { width: 100px; }
.student-remarks { margin-top: 12px; }
.record-form-actions { display: flex; gap: 10px; justify-content: flex-end; }
.attempt-history { display: grid; gap: 14px; }
.attempt-card { margin-bottom: 0; }
.attempt-card-heading { display: flex; justify-content: space-between; align-items: flex-start; gap: 12px; margin-bottom: 14px; }
.attempt-card-heading > div { display: flex; flex-direction: column; gap: 3px; }
.attempt-card-heading span { color: var(--muted); font-size: 12px; }
.attempt-parts { display: grid; gap: 8px; margin-bottom: 12px; }
.attempt-part-row { display: grid; grid-template-columns: minmax(70px, 1fr) minmax(130px, 180px) minmax(130px, 180px); align-items: center; gap: 12px; padding: 9px 11px; background: #f8f9fc; border-radius: 7px; }
.attempt-part-row label { display: flex; align-items: center; gap: 7px; color: var(--muted); font-size: 12px; }
.attempt-part-row input[type="number"] { min-width: 0; width: 100%; padding: 7px 8px; border: 1px solid var(--border); border-radius: 6px; }
.crop-job-form select { padding: 9px 11px; border: 1px solid var(--border); border-radius: 7px; background: #fff; font-size: 14px; }
.crop-job-list { display: flex; flex-direction: column; gap: 10px; }
.crop-job-card { display: grid; grid-template-columns: 1fr auto; gap: 6px 16px; padding: 14px; border: 1px solid var(--border); border-left: 4px solid #d5a528; border-radius: 8px; }
.crop-job-card > div:first-child { display: flex; flex-direction: column; gap: 3px; }
.crop-job-card > div:first-child span, .crop-job-details { color: var(--muted); font-size: 12px; }
.crop-job-status { align-self: start; padding: 3px 9px; border-radius: 20px; background: #fdf3d8; color: #92650a; font-size: 11px; font-weight: 700; text-transform: uppercase; }
.crop-job-card[data-status="completed"] { border-left-color: #237a3f; }
.crop-job-card[data-status="completed"] .crop-job-status { background: #e6f6ea; color: #237a3f; }
.crop-job-card[data-status="failed"], .crop-job-card[data-status="error"] { border-left-color: var(--danger); }
.crop-job-card[data-status="failed"] .crop-job-status, .crop-job-card[data-status="error"] .crop-job-status { background: #fdecec; color: var(--danger); }
.crop-job-details { grid-column: 1 / -1; overflow-wrap: anywhere; }
.paper-help { color: var(--muted); font-size: 13px; line-height: 1.5; }
.paper-upload-form input[type="file"] { padding: 8px; border: 1px solid var(--border); border-radius: 7px; background: #fff; }
.paper-empty-state { padding: 30px 20px; }
.paper-job-stage { text-transform: capitalize; }
.paper-selection-toolbar { display: flex; align-items: center; justify-content: space-between; gap: 12px; color: var(--muted); font-size: 13px; margin: 14px 0 8px; }
.paper-selection-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 7px 14px; max-height: 340px; overflow-y: auto; padding: 10px; border: 1px solid var(--border); border-radius: 8px; }
.paper-selection-choice { display: flex; align-items: flex-start; gap: 7px; font-size: 12px; cursor: pointer; overflow-wrap: anywhere; }
.paper-source-tree { max-height: 440px; overflow-y: auto; border: 1px solid var(--border); border-radius: 8px; }
.paper-source-node { border-bottom: 1px solid var(--border); }
.paper-source-node:last-child { border-bottom: 0; }
.paper-source-node summary { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 11px 13px; cursor: pointer; background: #f8f9fc; }
.paper-source-choice { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; }
.paper-source-count { color: var(--muted); font-size: 12px; white-space: nowrap; }
.paper-source-children { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 8px 16px; padding: 12px 16px 14px 36px; }
.paper-selection-row { display: flex; align-items: center; gap: 8px; min-width: 0; }
.paper-selection-row .paper-selection-choice { flex: 1; min-width: 0; }
.paper-download { display: inline-grid; place-items: center; flex: 0 0 30px; width: 30px; height: 30px; border-radius: 7px; color: var(--brand); background: #eaf0ff; text-decoration: none; font-size: 20px; font-weight: 800; line-height: 1; }
.paper-download:hover { background: var(--brand); color: #fff; }
.paper-source-node summary .paper-source-choice { flex: 1; min-width: 0; }
.paper-tabs { margin-bottom: 18px; }

.empty-state { text-align: center; color: var(--muted); padding: 60px 20px; }

/* ---------- Panels / tables (user management) ---------- */
.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 20px;
}
.panel-title { margin: 0 0 16px; font-size: 16px; }
.grid-form {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  align-items: end;
}
.field { display: flex; flex-direction: column; gap: 5px; }
.field-wide { grid-column: span 2; }
.field label { font-size: 12px; font-weight: 600; color: var(--muted); }
.field .hint { font-weight: 400; text-transform: none; }
.field input, .field select {
  padding: 9px 11px; border: 1px solid var(--border); border-radius: 7px; font-size: 14px;
}
.field-actions { display: flex; gap: 10px; }

.user-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.user-table th, .user-table td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); }
.user-table th { color: var(--muted); font-size: 12px; text-transform: uppercase; letter-spacing: 0.03em; }
.role-badge { padding: 2px 9px; border-radius: 20px; font-size: 11px; font-weight: 700; text-transform: uppercase; }
.role-admin { background: #fde8d0; color: #b0630a; }
.role-user { background: #dcefe0; color: #237a3f; }
.role-student { background: #dde8fb; color: #2749a8; }
.user-actions { display: flex; gap: 8px; }
.inline-form { display: inline; }
.audit-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.table-scroll { overflow-x: auto; }
.audit-table { min-width: 760px; }
.audit-time { white-space: nowrap; }
.audit-request { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 12px; }
.status-badge { display: inline-block; min-width: 34px; padding: 2px 7px; border-radius: 20px; text-align: center; font-size: 11px; font-weight: 700; }
.status-ok { background: #dcefe0; color: #237a3f; }
.status-error { background: #fbe1e1; color: #a42a2a; }

/* ---------- Modal ---------- */
.modal-backdrop {
  display: none;
  position: fixed; inset: 0; background: rgba(15,18,28,0.5);
  align-items: center; justify-content: center; z-index: 50;
}
.modal-backdrop.open { display: flex; }
.modal {
  background: var(--surface); border-radius: var(--radius);
  padding: 24px; width: 100%; max-width: 520px; box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

@media (max-width: 720px) {
  .sidebar { position: fixed; z-index: 40; height: 100vh; transform: translateX(-100%); }
  .sidebar.mobile-open { transform: translateX(0); }
  .field-wide { grid-column: span 1; }
  .student-filter-bar { grid-template-columns: 1fr; }
  .attempt-part-row { grid-template-columns: 1fr; }
  .student-match-count { padding-bottom: 0; }
}