/* ─── RESET & BASE ─────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue:        #1a4b8c;
  --blue-dark:   #0f2e5a;
  --blue-light:  #e8effa;
  --blue-mid:    #3567b5;
  --green:       #16a34a;
  --green-light: #dcfce7;
  --red:         #dc2626;
  --red-light:   #fee2e2;
  --amber:       #d97706;
  --amber-light: #fef3c7;
  --gray-50:     #f8fafc;
  --gray-100:    #f1f5f9;
  --gray-200:    #e2e8f0;
  --gray-400:    #94a3b8;
  --gray-500:    #64748b;
  --gray-700:    #334155;
  --gray-900:    #0f172a;
  --radius-sm:   8px;
  --radius:      14px;
  --radius-lg:   20px;
  --shadow-sm:   0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.04);
  --shadow:      0 4px 16px rgba(0,0,0,.10), 0 1px 4px rgba(0,0,0,.06);
  --shadow-lg:   0 16px 48px rgba(0,0,0,.16), 0 4px 12px rgba(0,0,0,.08);
}

html { -webkit-text-size-adjust: 100%; -moz-text-size-adjust: 100%; text-size-adjust: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", sans-serif;
  background: var(--gray-50);
  color: var(--gray-900);
  min-height: 100dvh;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
button { font-family: inherit; }

/* ─── HEADER ────────────────────────────────────────────────────────────── */
header {
  background: linear-gradient(135deg, var(--blue-dark) 0%, var(--blue) 60%, var(--blue-mid) 100%);
  padding: 0 1rem;
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: 0 2px 12px rgba(15,46,90,.3);
}
.header-inner {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}
.logo {
  font-size: 1.05rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: -.2px;
}
.logo span { color: #93c5fd; }
header nav { display: flex; gap: .25rem; align-items: center; }
header nav a {
  color: rgba(255,255,255,.75);
  text-decoration: none;
  font-size: .82rem;
  font-weight: 500;
  padding: .35rem .65rem;
  border-radius: 6px;
  transition: all .15s;
}
header nav a:hover { background: rgba(255,255,255,.15); color: #fff; }
header nav a.logout { color: #fca5a5; }

/* ─── MAIN ──────────────────────────────────────────────────────────────── */
main {
  max-width: 720px;
  margin: 0 auto;
  padding: 1.25rem 1rem 5rem;
}

/* ─── FLASH ─────────────────────────────────────────────────────────────── */
.flash {
  background: var(--amber-light);
  border: 1px solid #fbbf24;
  border-radius: var(--radius-sm);
  padding: .75rem 1rem;
  margin-bottom: 1rem;
  font-size: .9rem;
  color: #92400e;
}

/* ─── PAGE HEADER ───────────────────────────────────────────────────────── */
.page-header { margin-bottom: 1.25rem; }
.page-header h1 {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--blue-dark);
  letter-spacing: -.4px;
}
.page-header .subtitle { color: var(--gray-500); font-size: .9rem; margin-top: .2rem; }

.back-link {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
  color: var(--blue);
  text-decoration: none;
  font-size: .88rem;
  font-weight: 600;
  margin-bottom: .6rem;
  padding: .35rem .6rem;
  border-radius: 6px;
  margin-left: -.6rem;
  transition: background .15s;
}
.back-link:hover { background: var(--blue-light); }

/* ─── MONTH NAV ─────────────────────────────────────────────────────────── */
.month-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: .6rem 1rem;
  margin-bottom: 1.25rem;
  box-shadow: var(--shadow-sm);
}
.month-nav a {
  color: var(--blue);
  text-decoration: none;
  font-weight: 700;
  font-size: .95rem;
  padding: .35rem .7rem;
  border-radius: var(--radius-sm);
  transition: background .15s;
}
.month-nav a:hover { background: var(--blue-light); }
.month-nav strong { font-size: 1rem; font-weight: 800; color: var(--gray-900); }

/* ─── LEGEND ────────────────────────────────────────────────────────────── */
.legend {
  display: flex;
  gap: .5rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

/* ─── BADGES ────────────────────────────────────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  padding: .3rem .75rem;
  border-radius: 20px;
  font-size: .78rem;
  font-weight: 700;
  text-decoration: none;
  letter-spacing: .1px;
  transition: all .15s;
}
.badge-open  { background: var(--green-light); color: var(--green); }
.badge-open:hover { background: #bbf7d0; transform: scale(1.03); }
.badge-full  { background: var(--red-light); color: var(--red); }
.badge-empty { background: var(--gray-100); color: var(--gray-400); }
.badge-past  { background: var(--gray-100); color: var(--gray-400); font-size: .73rem; }

/* ─── CALENDAR / TIMETABLE ──────────────────────────────────────────────── */
.calendar { display: flex; flex-direction: column; gap: 1.25rem; }

.week-label {
  font-size: .68rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .7px;
  color: var(--gray-400);
  background: var(--gray-100);
  border-radius: 6px;
  padding: .22rem .65rem;
  display: inline-block;
  margin-bottom: .55rem;
}

.week-block-scroll { overflow-x: auto; border-radius: var(--radius); box-shadow: var(--shadow-sm); }
.week-block-scroll::-webkit-scrollbar { height: 3px; }
.week-block-scroll::-webkit-scrollbar-thumb { background: var(--gray-200); border-radius: 2px; }

.week-table {
  display: grid;
  grid-template-columns: 36px repeat(var(--cols), minmax(110px, 1fr));
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--gray-200);
  gap: 1px;
  min-width: max-content;
  width: 100%;
}

/* Corner & slot labels */
.wt-corner {
  background: var(--gray-50);
  grid-column: 1;
}
.wt-slot-lbl {
  background: var(--gray-50);
  font-size: .62rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .5px;
  color: var(--gray-500);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: .3rem .1rem;
  writing-mode: vertical-rl;
  transform: rotate(180deg);
}

/* Day header */
.wt-day-hdr {
  background: var(--gray-50);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: .45rem .6rem;
}
.wt-day-hdr.today { background: var(--blue-light); }
.wt-day-hdr.past { opacity: .5; }
.weekday { font-weight: 800; font-size: .82rem; color: var(--blue); }
.date-num {
  font-size: .75rem;
  font-weight: 700;
  color: var(--gray-500);
  background: var(--gray-200);
  padding: .1rem .35rem;
  border-radius: 5px;
}
.wt-day-hdr.today .date-num { background: var(--blue); color: #fff; }

/* Cells */
.wt-cell {
  background: #fff;
  padding: .55rem .6rem;
  display: flex;
  flex-direction: column;
  gap: .3rem;
  min-height: 64px;
}
.wt-cell.past { background: var(--gray-50); }
.wt-cell.today { background: #f5f8ff; }
.wt-no-slot {
  color: var(--gray-200);
  font-size: .8rem;
  text-align: center;
  margin: auto;
}

/* Topics inside cell */
.wt-topics { display: flex; flex-direction: column; gap: .2rem; margin-top: .1rem; }
.wt-topic {
  font-size: .7rem;
  line-height: 1.35;
  color: var(--gray-700);
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}
.wt-topic b { color: var(--blue); font-weight: 800; margin-right: .15rem; }

/* ─── SESSION DETAIL ────────────────────────────────────────────────────── */
.session-header {
  background: linear-gradient(135deg, var(--blue-dark), var(--blue-mid));
  color: #fff;
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
  box-shadow: var(--shadow);
}
.session-header h1 { font-size: 1.4rem; font-weight: 800; letter-spacing: -.3px; }
.session-header .slot-info {
  display: flex;
  align-items: center;
  gap: .75rem;
  margin-top: .5rem;
  flex-wrap: wrap;
}
.slot-time {
  font-size: .9rem;
  color: rgba(255,255,255,.85);
  font-weight: 500;
}
.slot-status-badge {
  display: inline-flex;
  align-items: center;
  padding: .25rem .7rem;
  border-radius: 20px;
  font-size: .78rem;
  font-weight: 700;
}
.slot-status-badge.open  { background: rgba(22,163,74,.25); color: #86efac; border: 1px solid rgba(134,239,172,.3); }
.slot-status-badge.full  { background: rgba(220,38,38,.25); color: #fca5a5; border: 1px solid rgba(252,165,165,.3); }

.topics-list { margin-bottom: 1.5rem; }
.topics-list h2 {
  font-size: .75rem;
  font-weight: 700;
  color: var(--gray-400);
  text-transform: uppercase;
  letter-spacing: .8px;
  margin-bottom: .75rem;
}

.topic-card {
  background: #fff;
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  margin-bottom: .65rem;
  box-shadow: var(--shadow-sm);
}
.topic-card--info { border-left: 3px solid var(--blue); }
.topic-tag {
  display: inline-block;
  background: var(--blue-light);
  color: var(--blue);
  font-size: .72rem;
  font-weight: 700;
  padding: .2rem .55rem;
  border-radius: 5px;
  margin-bottom: .35rem;
  letter-spacing: .1px;
}
.topic-tag.small { font-size: .68rem; }
.topic-card h3 { font-size: .98rem; font-weight: 700; color: var(--gray-900); line-height: 1.35; }

/* ─── REGISTER ACTION ───────────────────────────────────────────────────── */
.register-action {
  position: sticky;
  bottom: 1rem;
  text-align: center;
}

.btn-register-session {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-mid) 100%);
  color: #fff;
  border: none;
  padding: 1rem 2.5rem;
  border-radius: 50px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: .2px;
  box-shadow: 0 4px 20px rgba(26,75,140,.4);
  transition: all .2s;
  width: 100%;
  max-width: 360px;
}
.btn-register-session:hover { transform: translateY(-2px); box-shadow: 0 8px 28px rgba(26,75,140,.5); }
.btn-register-session:active { transform: translateY(0); }

.btn-disabled-block {
  display: block;
  text-align: center;
  color: var(--gray-400);
  background: var(--gray-100);
  border-radius: 50px;
  padding: 1rem;
  font-weight: 600;
  max-width: 360px;
  margin: 0 auto;
}

/* ─── MODAL (Bottom sheet on mobile) ────────────────────────────────────── */
.modal {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: flex-end;
  justify-content: center;
}
.modal.hidden { display: none; }

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
  z-index: 199;
  animation: fadeIn .2s ease;
}
.modal-overlay.hidden { display: none; }

.modal-box {
  background: #fff;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  padding: 1.5rem 1.25rem 2rem;
  width: 100%;
  max-width: 520px;
  z-index: 201;
  box-shadow: var(--shadow-lg);
  animation: slideUp .25s cubic-bezier(.32,1,.5,1);
}
.modal-handle {
  width: 40px;
  height: 4px;
  background: var(--gray-200);
  border-radius: 2px;
  margin: 0 auto .75rem;
}
.modal-box h2 { font-size: 1.15rem; font-weight: 800; color: var(--gray-900); margin-bottom: .25rem; }
.modal-topic { color: var(--gray-500); font-size: .85rem; margin-bottom: 1.25rem; }

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideUp { from { transform: translateY(100%); } to { transform: translateY(0); } }

/* ─── FORMS ─────────────────────────────────────────────────────────────── */
.form-group { margin-bottom: 1rem; }
.form-group label {
  display: block;
  font-size: .82rem;
  font-weight: 700;
  color: var(--gray-700);
  margin-bottom: .4rem;
  text-transform: uppercase;
  letter-spacing: .4px;
}
.form-group input[type=text],
.form-group input[type=password],
.form-group input[type=number] {
  width: 100%;
  padding: .75rem 1rem;
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  color: var(--gray-900);
  background: var(--gray-50);
  transition: all .15s;
  -webkit-appearance: none;
}
.form-group input:focus {
  outline: none;
  border-color: var(--blue);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(26,75,140,.12);
}

/* ─── VAI TRÒ RADIO ─────────────────────────────────────────────────────── */
.vai-tro-group { display: flex; flex-direction: column; gap: .5rem; margin-top: .25rem; }
.radio-label {
  display: flex;
  align-items: center;
  gap: .65rem;
  font-weight: 500;
  font-size: .95rem;
  cursor: pointer;
  padding: .7rem 1rem;
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius-sm);
  background: var(--gray-50);
  transition: all .15s;
  color: var(--gray-700);
}
.radio-label:hover { background: var(--blue-light); border-color: var(--blue); }
.radio-label input[type=radio] {
  accent-color: var(--blue);
  width: 18px;
  height: 18px;
  cursor: pointer;
  flex-shrink: 0;
}
.radio-label:has(input:checked) {
  background: var(--blue-light);
  border-color: var(--blue);
  color: var(--blue);
  font-weight: 700;
}

/* ─── FORM ACTIONS ──────────────────────────────────────────────────────── */
.form-actions { display: flex; gap: .65rem; margin-top: 1.25rem; }
.btn-submit {
  flex: 1;
  background: linear-gradient(135deg, var(--blue), var(--blue-mid));
  color: #fff;
  border: none;
  padding: .85rem 1.5rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: .95rem;
  font-weight: 700;
  transition: all .15s;
  text-decoration: none;
  text-align: center;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.btn-submit:hover { opacity: .9; transform: translateY(-1px); }
.btn-submit:active { transform: translateY(0); }

.btn-cancel {
  background: var(--gray-100);
  color: var(--gray-700);
  border: 1.5px solid var(--gray-200);
  padding: .85rem 1.25rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: .95rem;
  font-weight: 600;
  transition: background .15s;
  white-space: nowrap;
}
.btn-cancel:hover { background: var(--gray-200); }

/* ─── LOGIN ─────────────────────────────────────────────────────────────── */
.login-box {
  max-width: 380px;
  margin: 3.5rem auto;
  background: #fff;
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 2.25rem 1.75rem;
  box-shadow: var(--shadow);
}
.login-logo {
  text-align: center;
  margin-bottom: 1.5rem;
}
.login-logo-icon {
  width: 56px;
  height: 56px;
  background: var(--blue-light);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
  margin: 0 auto .75rem;
}
.login-box h1 { text-align: center; color: var(--blue-dark); font-size: 1.25rem; font-weight: 800; }
.login-box .sub { text-align: center; color: var(--gray-500); font-size: .85rem; margin-top: .25rem; margin-bottom: 1.5rem; }
.btn-submit-full { width: 100%; margin-top: .5rem; }

/* ─── SUCCESS PAGE ──────────────────────────────────────────────────────── */
.success-page {
  max-width: 480px;
  margin: 2rem auto;
  text-align: center;
}
.success-icon-wrap { margin-bottom: 1.25rem; }
.success-icon {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, #16a34a, #22c55e);
  color: #fff;
  font-size: 2rem;
  line-height: 72px;
  margin: 0 auto;
  box-shadow: 0 8px 24px rgba(22,163,74,.35);
  animation: popIn .4s cubic-bezier(.175,.885,.32,1.275);
}
@keyframes popIn { from { transform: scale(0); opacity: 0; } to { transform: scale(1); opacity: 1; } }
.success-title { font-size: 1.5rem; font-weight: 800; color: var(--green); margin-bottom: .4rem; }
.success-sub { color: var(--gray-500); margin-bottom: 1.25rem; }
.success-card {
  background: #fff;
  border: 1.5px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  text-align: left;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}
.success-date {
  font-size: .9rem;
  color: var(--gray-700);
  font-weight: 600;
  margin-bottom: .85rem;
  padding-bottom: .75rem;
  border-bottom: 1px solid var(--gray-100);
}
.success-topic { margin-bottom: .65rem; }
.success-topic:last-child { margin-bottom: 0; }
.success-topic-name { font-size: .95rem; font-weight: 600; color: var(--gray-900); margin-top: .25rem; }
.btn-back-home {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--blue-light);
  color: var(--blue);
  border-radius: 50px;
  padding: .85rem 2rem;
  font-weight: 700;
  font-size: .95rem;
  text-decoration: none;
  transition: all .15s;
  width: 100%;
}
.btn-back-home:hover { background: #c7d9f5; }

/* ─── ADMIN SESSIONS TABLE ──────────────────────────────────────────────── */
.hint { color: var(--gray-500); font-size: .88rem; margin-bottom: 1rem; }
.sessions-table-wrap { overflow-x: auto; border-radius: var(--radius); box-shadow: var(--shadow-sm); }
.sessions-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .875rem;
  background: #fff;
}
.sessions-table th {
  background: var(--blue-dark);
  color: rgba(255,255,255,.9);
  padding: .7rem .8rem;
  text-align: left;
  font-weight: 700;
  font-size: .78rem;
  text-transform: uppercase;
  letter-spacing: .4px;
  white-space: nowrap;
}
.sessions-table td {
  padding: .6rem .8rem;
  border-bottom: 1px solid var(--gray-100);
  vertical-align: middle;
}
.sessions-table tr:last-child td { border-bottom: none; }
.sessions-table tr:hover td { background: var(--gray-50); }
.topic-select {
  width: 100%;
  min-width: 200px;
  padding: .4rem .5rem;
  border: 1.5px solid var(--gray-200);
  border-radius: 6px;
  font-size: .82rem;
  background: #fff;
  color: var(--gray-900);
}
.topic-select:focus { outline: none; border-color: var(--blue); }
.capacity-input {
  width: 64px;
  padding: .4rem .5rem;
  border: 1.5px solid var(--gray-200);
  border-radius: 6px;
  text-align: center;
  font-size: .85rem;
}
.count-cell { text-align: center; font-weight: 700; color: var(--gray-700); }
.btn-save {
  background: var(--blue);
  color: #fff;
  border: none;
  padding: .4rem .9rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: .82rem;
  font-weight: 600;
  transition: background .15s;
  white-space: nowrap;
}
.btn-save:hover { background: var(--blue-dark); }

/* ─── ADMIN REGISTRATIONS ───────────────────────────────────────────────── */
.admin-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  flex-wrap: wrap;
  gap: .5rem;
}
.total-count { color: var(--gray-500); font-size: .88rem; }
.btn-export {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
  background: var(--green);
  color: #fff;
  padding: .5rem 1rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-size: .85rem;
  font-weight: 700;
  transition: background .15s;
}
.btn-export:hover { background: #15803d; }
.table-wrap { overflow-x: auto; border-radius: var(--radius); box-shadow: var(--shadow-sm); }
.reg-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .85rem;
  background: #fff;
}
.reg-table th {
  background: var(--blue-dark);
  color: rgba(255,255,255,.9);
  padding: .65rem .75rem;
  text-align: left;
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .4px;
}
.reg-table td { padding: .6rem .75rem; border-bottom: 1px solid var(--gray-100); vertical-align: middle; }
.reg-table tr:last-child td { border-bottom: none; }
.reg-table tr:hover td { background: var(--gray-50); }
.time-cell { color: var(--gray-400); font-size: .75rem; }
.empty { color: var(--gray-400); text-align: center; padding: 3rem; }

/* ─── VAI TRÒ BADGES (admin) ────────────────────────────────────────────── */
.vai-tro-badge {
  display: inline-block;
  font-size: .72rem;
  padding: .18rem .55rem;
  border-radius: 5px;
  font-weight: 700;
  white-space: nowrap;
}
.vt-thánh-đồ      { background: var(--green-light); color: var(--green); }
.vt-địa-vực-trưởng { background: #dbeafe; color: #1d4ed8; }
.vt-khu-vực-trưởng { background: var(--amber-light); color: var(--amber); }

/* ─── RESPONSIVE ────────────────────────────────────────────────────────── */
@media (max-width: 540px) {
  .week-table { grid-template-columns: 30px repeat(var(--cols), minmax(100px, 1fr)); }
  .wt-slot-lbl { font-size: .55rem; }
  .wt-topic { font-size: .67rem; }

  .modal-box { padding: 1.25rem 1rem 2.5rem; border-radius: 24px 24px 0 0; }
  .session-header { border-radius: var(--radius); padding: 1.15rem; }
  .btn-register-session { font-size: .95rem; padding: .9rem 2rem; }

  header nav { display: none; }
  .sessions-table, .reg-table { font-size: .8rem; }
}

@media (min-width: 541px) {
  .modal { align-items: center; }
  .modal-box { border-radius: var(--radius-lg); max-width: 480px; padding: 2rem; }
  .modal-handle { display: none; }
}