/* ============================================================
   DIU CPC Attendance System — Premium CSS
   Dhaka International University Computer Programming Club
   ============================================================ */

/* ---------- CSS Custom Properties ---------- */
:root {
  --blue-400: hsl(213, 94%, 68%);
  --blue-500: hsl(217, 91%, 60%);
  --blue-600: hsl(221, 83%, 53%);
  --blue-700: hsl(224, 76%, 48%);
  --cyan-400: hsl(187, 92%, 69%);
  --cyan-500: hsl(188, 86%, 53%);

  --bg-base: hsl(220, 26%, 6%);
  --bg-surface: hsl(220, 20%, 10%);
  --bg-card: hsl(220, 18%, 12%);
  --bg-input: hsl(220, 18%, 14%);
  --bg-checkbox: hsla(220, 20%, 14%, 0.5);
  --bg-header: rgba(10, 13, 20, 0.85);

  --border-color: hsl(220, 20%, 18%);
  --border-focus: hsl(217, 91%, 60%);

  --text-primary: hsl(220, 15%, 95%);
  --text-secondary: hsl(220, 10%, 65%);
  --text-muted: hsl(220, 8%, 45%);

  --success: hsl(142, 76%, 36%);
  --danger: hsl(0, 72%, 51%);
  --warning: hsl(38, 92%, 50%);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
  --shadow-glow: 0 0 40px hsla(217, 91%, 60%, 0.15);

  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: 0.15s ease;
}

:root[data-theme="light"] {
  --bg-base: hsl(220, 26%, 96%);
  --bg-surface: hsl(220, 20%, 98%);
  --bg-card: hsl(0, 0%, 100%);
  --bg-input: hsl(220, 18%, 94%);
  --bg-checkbox: hsla(220, 20%, 92%, 0.8);
  --bg-header: hsla(0, 0%, 100%, 0.85);
  --border-color: hsl(220, 20%, 88%);
  --text-primary: hsl(220, 15%, 15%);
  --text-secondary: hsl(220, 10%, 35%);
  --text-muted: hsl(220, 8%, 55%);
}

.theme-toggle {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  padding: 0.2rem;
  border-radius: 50%;
  transition: transform var(--transition);
}
.theme-toggle:hover {
  transform: scale(1.1);
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', system-ui, sans-serif;
  background-color: var(--bg-base);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

/* ---------- Background Effects ---------- */
.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(to right, hsl(220, 20%, 14%, 0.6) 1px, transparent 1px),
    linear-gradient(to bottom, hsl(220, 20%, 14%, 0.6) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
  z-index: 0;
}

.bg-glow {
  position: fixed;
  border-radius: 50%;
  filter: blur(80px);
  pointer-events: none;
  z-index: 0;
  opacity: 0.18;
}

.bg-glow-1 {
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, hsl(217, 91%, 60%), transparent 70%);
  top: -200px;
  right: -100px;
}

.bg-glow-2 {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, hsl(188, 86%, 53%), transparent 70%);
  bottom: -200px;
  left: -100px;
}

/* ---------- Layout ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  position: relative;
  z-index: 1;
}

/* ---------- Header ---------- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-header);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 0;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

/* Logo & Brand */
.header-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.logo-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.logo-pulse {
  position: absolute;
  inset: -4px;
  border-radius: 50%;
  background: radial-gradient(circle, hsla(217, 91%, 60%, 0.3), transparent 70%);
  animation: pulse 2.5s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 0.4; transform: scale(1); }
  50% { opacity: 0.8; transform: scale(1.15); }
}

.logo-img {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  object-fit: contain;
  position: relative;
  z-index: 1;
  filter: drop-shadow(0 0 10px hsla(217, 91%, 60%, 0.45));
  transition: filter var(--transition);
}

.logo-img:hover {
  filter: drop-shadow(0 0 16px hsla(188, 86%, 53%, 0.6));
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-name {
  font-weight: 800;
  font-size: 1rem;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

.brand-tagline {
  font-size: 0.65rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* Course badge */
.header-center {
  flex: 1;
  display: flex;
  justify-content: center;
}

.course-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: hsl(142, 76%, 70%);
  background: hsla(142, 76%, 36%, 0.15);
  border: 1px dashed hsla(142, 76%, 36%, 0.4);
  padding: 0.35rem 0.9rem;
  border-radius: 100px;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.badge-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: hsl(142, 76%, 50%);
  box-shadow: 0 0 6px hsl(142, 76%, 50%);
  animation: blink 1.5s ease-in-out infinite;
  flex-shrink: 0;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

/* Clock */
.header-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  flex-shrink: 0;
}

.live-clock {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--blue-400);
  letter-spacing: 0.05em;
}

.date-display {
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

/* ---------- Main ---------- */
.main {
  padding: 2.5rem 1.5rem 4rem;
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

/* ---------- Animations ---------- */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  animation: fadeUp 0.6s ease forwards;
}

.fade-up:nth-child(1) { animation-delay: 0.1s; }
.fade-up:nth-child(2) { animation-delay: 0.25s; }
.fade-up:nth-child(3) { animation-delay: 0.4s; }

@keyframes fadeUp {
  to { opacity: 1; transform: translateY(0); }
}

/* ---------- Hero Section ---------- */
.hero-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
  align-items: center;
  padding: 2rem 0 0.5rem;
}

.section-label {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--blue-400);
  margin-bottom: 0.75rem;
}

.label-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--blue-400);
}

.hero-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 1rem;
}

.gradient-text {
  background: linear-gradient(90deg, var(--blue-400), var(--cyan-400));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 420px;
}

.hero-desc strong {
  color: var(--text-primary);
}

/* Stat Cards */
.hero-stats {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.stat-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  transition: border-color var(--transition), transform var(--transition);
}

.stat-card:hover {
  border-color: var(--blue-600);
  transform: translateX(4px);
}

.stat-icon {
  font-size: 1.8rem;
  width: 48px;
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: 800;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  line-height: 1;
}

.stat-label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.03em;
  margin-top: 0.2rem;
}

/* ---------- Form Section ---------- */
.form-section {
  position: relative;
}

.form-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  position: relative;
  overflow: hidden;
}

.form-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  padding: 1px;
  background: linear-gradient(135deg, hsla(217, 91%, 60%, 0.3), transparent 50%, hsla(188, 86%, 53%, 0.2));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}

.form-card-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

.form-header-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, hsla(217, 91%, 60%, 0.2), hsla(188, 86%, 53%, 0.1));
  border: 1px solid hsla(217, 91%, 60%, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  flex-shrink: 0;
}

.form-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.form-card-subtitle {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

/* Form Layout */
.attendance-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: 0.02em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.label-icon {
  font-size: 0.9rem;
}

.form-input {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.9rem;
  font-family: 'Inter', sans-serif;
  transition: border-color var(--transition), box-shadow var(--transition), background var(--transition);
  outline: none;
}

.form-input::placeholder {
  color: var(--text-muted);
  opacity: 0.7;
}

.form-input:focus {
  border-color: var(--border-focus);
  background: hsla(217, 91%, 60%, 0.05);
  box-shadow: 0 0 0 3px hsla(217, 91%, 60%, 0.15);
}

.form-input:valid:not(:placeholder-shown) {
  border-color: hsl(142, 76%, 36%);
}

.form-select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.9rem center;
  padding-right: 2.5rem;
}

.form-select option {
  background: var(--bg-card);
  color: var(--text-primary);
}

.form-error {
  font-size: 0.75rem;
  color: hsl(0, 72%, 60%);
  min-height: 1rem;
  display: block;
  font-weight: 500;
}

/* Checkbox */
.checkbox-group {
  background: var(--bg-checkbox);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
}

.checkbox-label {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  cursor: pointer;
  font-size: 0.87rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.checkbox-input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.checkbox-custom {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: 5px;
  background: var(--bg-input);
  flex-shrink: 0;
  margin-top: 2px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
  position: relative;
}

.checkbox-input:checked + .checkbox-custom {
  background: var(--blue-600);
  border-color: var(--blue-600);
  box-shadow: 0 0 10px hsla(217, 91%, 60%, 0.4);
}

.checkbox-input:checked + .checkbox-custom::after {
  content: '✓';
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
}

/* Submit Button */
.btn-submit {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  width: 100%;
  padding: 1rem 2rem;
  background: linear-gradient(135deg, var(--blue-600), var(--cyan-500));
  color: white;
  font-size: 1rem;
  font-weight: 700;
  font-family: 'Inter', sans-serif;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  overflow: hidden;
  letter-spacing: 0.01em;
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 20px hsla(217, 91%, 60%, 0.35);
}

.btn-shimmer {
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.18) 50%, transparent 100%);
  transform: translateX(-100%);
  transition: transform 0.7s ease;
}

.btn-submit:hover .btn-shimmer {
  transform: translateX(100%);
}

.btn-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px hsla(217, 91%, 60%, 0.5);
}

.btn-submit:active {
  transform: translateY(0);
}

.btn-submit:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

.btn-arrow {
  font-size: 1.1rem;
  transition: transform var(--transition);
}

.btn-submit:hover .btn-arrow {
  transform: translateX(4px);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--bg-card);
  border: 1px solid hsl(142, 76%, 36%);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  display: none;
  align-items: flex-start;
  gap: 0.75rem;
  z-index: 200;
  max-width: 360px;
  box-shadow: var(--shadow-lg), 0 0 20px hsla(142, 76%, 36%, 0.2);
  animation: slideIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.toast.show {
  display: flex;
}

@keyframes slideIn {
  from { transform: translateX(120%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

.toast-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

.toast strong {
  display: block;
  font-size: 0.9rem;
  color: hsl(142, 76%, 70%);
  margin-bottom: 0.2rem;
}

.toast p {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.toast-close {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1rem;
  padding: 0 0.2rem;
  margin-left: auto;
  flex-shrink: 0;
  transition: color var(--transition-fast);
}

.toast-close:hover {
  color: var(--text-primary);
}

/* ---------- Table Section ---------- */
.table-section {
  animation: fadeUp 0.6s ease 0.3s both;
}

.table-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.table-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.table-title {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.table-subtitle {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

.table-actions {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

.btn-action {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1rem;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.82rem;
  font-weight: 600;
  font-family: 'Inter', sans-serif;
  cursor: pointer;
  transition: all var(--transition);
}

.btn-action:hover {
  border-color: var(--blue-600);
  color: var(--text-primary);
  background: hsla(217, 91%, 60%, 0.1);
}

.btn-danger:hover {
  border-color: var(--danger);
  color: hsl(0, 72%, 60%);
  background: hsla(0, 72%, 51%, 0.1);
}

/* Search */
.search-bar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.65rem 1rem;
  margin-bottom: 1.25rem;
  transition: border-color var(--transition);
}

.search-bar:focus-within {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px hsla(217, 91%, 60%, 0.15);
}

.search-icon {
  font-size: 1rem;
  flex-shrink: 0;
}

.search-input {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-size: 0.88rem;
  font-family: 'Inter', sans-serif;
}

.search-input::placeholder {
  color: var(--text-muted);
}

/* Table */
.table-wrapper {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.attendance-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.83rem;
}

.attendance-table thead tr {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
}

.attendance-table th {
  padding: 0.85rem 1rem;
  text-align: left;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  white-space: nowrap;
}

.attendance-table tbody tr {
  border-bottom: 1px solid var(--border-color);
  transition: background var(--transition-fast);
}

.attendance-table tbody tr:last-child {
  border-bottom: none;
}

.attendance-table tbody tr:hover {
  background: hsla(217, 91%, 60%, 0.04);
}

.attendance-table td {
  padding: 0.85rem 1rem;
  color: var(--text-secondary);
  white-space: nowrap;
  max-width: 180px;
  overflow: hidden;
  text-overflow: ellipsis;
}

.attendance-table td:first-child {
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-muted);
  font-size: 0.75rem;
}

.attendance-table td .name-cell {
  font-weight: 600;
  color: var(--text-primary);
}

.attendance-table td .badge-pill {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  border-radius: 100px;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.03em;
}

.badge-dept {
  background: hsla(217, 91%, 60%, 0.15);
  color: var(--blue-400);
}

.badge-batch {
  background: hsla(188, 86%, 53%, 0.1);
  color: var(--cyan-400);
}

.delete-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  font-size: 1rem;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast), background var(--transition-fast);
}

.delete-btn:hover {
  color: hsl(0, 72%, 60%);
  background: hsla(0, 72%, 51%, 0.1);
}

/* Empty state */
.table-empty {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-muted);
  display: none;
}

.table-empty.show {
  display: block;
}

.empty-icon {
  display: block;
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
}

.table-empty p {
  font-size: 0.88rem;
}

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--border-color);
  background: var(--bg-surface);
  padding: 2rem 0;
  position: relative;
  z-index: 1;
  margin-top: 1rem;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.footer-logo-img {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  object-fit: contain;
  flex-shrink: 0;
  filter: drop-shadow(0 0 6px hsla(217, 91%, 60%, 0.3));
}

.footer-name {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--text-primary);
}

.footer-sub {
  font-size: 0.7rem;
  color: var(--text-muted);
  line-height: 1.4;
  margin-top: 0.15rem;
}

.footer-center {
  text-align: center;
}

.footer-course {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.footer-copy {
  font-size: 0.73rem;
  color: var(--text-muted);
}

.footer-copy a {
  color: var(--blue-400);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-copy a:hover {
  color: var(--cyan-400);
}

.footer-links {
  display: flex;
  gap: 1rem;
}

.footer-link {
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-link:hover {
  color: var(--blue-400);
}

/* Input validation states */
.form-input.error {
  border-color: hsl(0, 72%, 51%);
  box-shadow: 0 0 0 3px hsla(0, 72%, 51%, 0.15);
}

.form-input.success {
  border-color: var(--success);
}

.dept-fixed {
  background: hsla(217, 91%, 60%, 0.06) !important;
  border-color: hsla(217, 91%, 60%, 0.25) !important;
  color: var(--blue-400) !important;
  cursor: not-allowed;
  font-weight: 600;
  letter-spacing: 0.01em;
}

/* ---------- Feedback Section ---------- */
.feedback-section {
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition);
}

.feedback-section:focus-within,
.feedback-section:has(.feedback-body:not([style*="none"])) {
  border-color: hsla(217, 91%, 60%, 0.35);
}

.feedback-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast);
  gap: 1rem;
}

.feedback-toggle:hover {
  background: hsla(217, 91%, 60%, 0.04);
}

.feedback-toggle-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.feedback-toggle-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
}

.feedback-toggle-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.feedback-toggle-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.optional-badge {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--blue-400);
  background: hsla(217, 91%, 60%, 0.12);
  border: 1px solid hsla(217, 91%, 60%, 0.2);
  padding: 0.15rem 0.5rem;
  border-radius: 100px;
}

.feedback-chevron {
  font-size: 1.2rem;
  color: var(--text-muted);
  transition: transform var(--transition);
  flex-shrink: 0;
}

.feedback-chevron.open {
  transform: rotate(180deg);
}

.feedback-body {
  padding: 0 1.25rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
  animation: fadeUp 0.25s ease;
  border-top: 1px dashed var(--border-color);
  padding-top: 1.25rem;
}

/* Star Rating */
.star-rating {
  display: flex;
  gap: 0.3rem;
  margin-top: 0.4rem;
}

.star {
  background: none;
  border: none;
  font-size: 2rem;
  color: var(--border-color);
  cursor: pointer;
  transition: color var(--transition-fast), transform var(--transition-fast);
  padding: 0 0.1rem;
  line-height: 1;
}

.star:hover,
.star.active {
  color: hsl(38, 92%, 55%);
  transform: scale(1.15);
}

.star-label {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
  min-height: 1.1em;
  font-style: italic;
}

/* Difficulty Pills */
.difficulty-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.4rem;
}

.diff-pill {
  padding: 0.45rem 1rem;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: 100px;
  color: var(--text-secondary);
  font-size: 0.82rem;
  font-weight: 500;
  font-family: 'Inter', sans-serif;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.diff-pill:hover {
  border-color: var(--blue-600);
  color: var(--text-primary);
  background: hsla(217, 91%, 60%, 0.08);
}

.diff-pill.selected {
  background: linear-gradient(135deg, hsla(217, 91%, 60%, 0.2), hsla(188, 86%, 53%, 0.15));
  border-color: var(--blue-500);
  color: var(--blue-400);
  font-weight: 600;
}

/* Textarea */
.feedback-textarea {
  resize: vertical;
  min-height: 80px;
  font-family: 'Inter', sans-serif;
  line-height: 1.6;
}

.char-count {
  font-size: 0.72rem;
  color: var(--text-muted);
  text-align: right;
  margin-top: 0.3rem;
  font-family: 'JetBrains Mono', monospace;
}

/* ---------- Google Sheets Banner ---------- */
.sheets-banner {
  background: var(--bg-card);
  border: 1px solid hsla(142, 76%, 36%, 0.3);
  border-radius: var(--radius-xl);
  padding: 1.25rem 1.5rem;
  box-shadow: 0 0 30px hsla(142, 76%, 36%, 0.08);
  position: relative;
  overflow: hidden;
}

.sheets-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, hsla(142, 76%, 36%, 0.05), transparent 60%);
  pointer-events: none;
}

.sheets-banner-inner {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
  position: relative;
  z-index: 1;
}

.sheets-icon-wrap {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: hsla(142, 76%, 36%, 0.12);
  border: 1px solid hsla(142, 76%, 36%, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.sheets-info {
  flex: 1;
  min-width: 180px;
}

.sheets-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}

.sheets-desc {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.sheets-input-wrap {
  display: flex;
  gap: 0.6rem;
  align-items: center;
  flex: 2;
  min-width: 260px;
}

.sheets-url-input {
  flex: 1;
  font-size: 0.82rem !important;
  padding: 0.6rem 0.9rem !important;
}

.btn-connect {
  padding: 0.6rem 1.25rem;
  background: linear-gradient(135deg, hsl(142, 76%, 30%), hsl(160, 70%, 35%));
  color: white;
  font-size: 0.85rem;
  font-weight: 700;
  font-family: 'Inter', sans-serif;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition);
  box-shadow: 0 2px 12px hsla(142, 76%, 36%, 0.35);
  flex-shrink: 0;
}

.btn-connect:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px hsla(142, 76%, 36%, 0.5);
}

.btn-connect.connected {
  background: linear-gradient(135deg, hsl(217, 91%, 50%), hsl(188, 86%, 45%));
  box-shadow: 0 2px 12px hsla(217, 91%, 60%, 0.35);
}

.sheets-status {
  font-size: 0.78rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  white-space: nowrap;
}

.sheets-status.ok { color: hsl(142, 76%, 55%); }
.sheets-status.err { color: hsl(0, 72%, 60%); }
.sheets-status.syncing { color: var(--blue-400); }

/* Sheet sync indicator in table */
.sync-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 100px;
  background: hsla(142, 76%, 36%, 0.15);
  color: hsl(142, 76%, 60%);
  margin-left: 0.4rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 1024px) {
  .hero-title { font-size: 2.8rem; }
  .table-card { padding: 1.5rem; }
}

@media (max-width: 900px) {
  .hero-section {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2rem;
  }
  .hero-desc { margin: 1rem auto; }
  
  .hero-stats {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
  }
  .stat-card {
    flex: 1;
    min-width: 150px;
    max-width: 250px;
  }
}

@media (max-width: 680px) {
  .hero-title { font-size: 2.2rem; }
  .form-row { grid-template-columns: 1fr; }
  
  .header-center { display: none; }
  .header-inner { justify-content: space-between; }
  
  .form-card { padding: 1.25rem; }
  .table-card { padding: 1rem; }
  
  .footer-inner {
    flex-direction: column;
    text-align: center;
    gap: 1.25rem;
  }
  .footer-links { justify-content: center; }
  .hero-stats { flex-direction: column; align-items: center; }
  .stat-card { max-width: 100%; width: 100%; }

  .feedback-toggle {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  .feedback-chevron { display: none; }

  /* Better mobile table scrolling */
  .table-wrapper {
    margin: 0 -1rem; /* Full bleed on mobile */
    border-radius: 0;
    border-left: none;
    border-right: none;
    -webkit-overflow-scrolling: touch;
  }
  .attendance-table th, .attendance-table td {
    padding: 0.75rem 0.6rem;
  }
  .attendance-table td {
    max-width: 140px;
  }
}

@media (max-width: 480px) {
  .hero-title { font-size: 1.8rem; }
  .btn-submit { font-size: 0.9rem; padding: 0.8rem; }
  .form-card-header { flex-direction: column; align-items: flex-start; gap: 0.5rem; }
  .form-header-icon { margin-bottom: 0.5rem; }
  
  /* Make table actions stack */
  .table-header { flex-direction: column; align-items: flex-start; }
  .table-actions { width: 100%; flex-wrap: wrap; }
  .btn-action { flex: 1; justify-content: center; text-align: center; }
}