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

:root {
  --bg-primary: #0f0f23;
  --bg-secondary: #1a1a3e;
  --bg-card: rgba(255, 255, 255, 0.06);
  --bg-card-hover: rgba(255, 255, 255, 0.1);
  --border-glass: rgba(255, 255, 255, 0.12);
  --text-primary: #e8e8f0;
  --text-secondary: #a0a0c0;
  --text-muted: #6a6a8e;
  --accent: #6c5ce7;
  --accent-light: #a29bfe;
  --accent-glow: rgba(108, 92, 231, 0.3);
  --success: #00b894;
  --success-bg: rgba(0, 184, 148, 0.15);
  --danger: #ff6b6b;
  --danger-bg: rgba(255, 107, 107, 0.15);
  --warning: #fdcb6e;
  --warning-bg: rgba(253, 203, 110, 0.15);
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font: 'Rubik', sans-serif;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  background: linear-gradient(135deg, var(--bg-primary) 0%, #1a1a3e 50%, #0f0f23 100%);
  color: var(--text-primary);
  min-height: 100vh;
  direction: rtl;
  overflow-x: hidden;
  padding-bottom: 2rem;
}

body::before {
  content: '';
  position: fixed;
  top: -50%;
  right: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 30% 30%, rgba(108, 92, 231, 0.08) 0%, transparent 50%),
              radial-gradient(circle at 70% 70%, rgba(0, 184, 148, 0.05) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

/* ====== GLASS CARD ====== */
.glass-card {
  background: var(--bg-card);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* ====== HEADER ====== */
#app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 15, 35, 0.85);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom: 1px solid var(--border-glass);
  padding: 1rem 1.25rem 0.75rem;
  text-align: center;
}

#app-header h1 {
  font-size: 1.3rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--accent-light), var(--success));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.month-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
}

.nav-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  color: var(--text-primary);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  font-size: 1.3rem;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav-btn:hover {
  background: var(--accent);
  border-color: var(--accent);
  transform: scale(1.1);
}

.nav-btn:active {
  transform: scale(0.95);
}

.month-label {
  font-size: 1.1rem;
  font-weight: 500;
  min-width: 140px;
  color: var(--text-primary);
}

/* ====== SUMMARY BAR ====== */
.summary-bar {
  margin: 1rem 1rem 0;
  padding: 1rem;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.5rem;
  position: relative;
  z-index: 1;
}

.summary-item {
  text-align: center;
}

.summary-value {
  display: block;
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
}

.summary-label {
  display: block;
  font-size: 0.7rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

#summary-balance.positive {
  color: var(--success);
}

#summary-balance.negative {
  color: var(--danger);
}

/* ====== SECTION TITLES ====== */
.section-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 0 0.25rem;
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.25rem;
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
}

#quick-log-section {
  padding: 1rem 1.25rem 0;
  position: relative;
  z-index: 1;
}

#quick-log-section .section-title {
  margin-bottom: 0.75rem;
}

/* ====== QUICK LOG GRID ====== */
.quick-log-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 0.6rem;
}

.quick-btn {
  background: linear-gradient(135deg, var(--accent) 0%, #5a4bd1 100%);
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.85rem 0.5rem;
  color: white;
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  text-align: center;
  line-height: 1.3;
}

.quick-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.2), transparent);
  opacity: 0;
  transition: var(--transition);
}

.quick-btn:hover::before {
  opacity: 1;
}

.quick-btn:active {
  transform: scale(0.93);
}

.quick-btn.flash {
  animation: flashGreen 0.6s ease;
}

@keyframes flashGreen {
  0% { background: linear-gradient(135deg, var(--accent) 0%, #5a4bd1 100%); }
  40% { background: linear-gradient(135deg, var(--success) 0%, #00a885 100%); transform: scale(1.05); }
  100% { background: linear-gradient(135deg, var(--accent) 0%, #5a4bd1 100%); }
}

/* ====== STUDENT CARDS ====== */
.students-list {
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  position: relative;
  z-index: 1;
}

.student-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius);
  padding: 1rem 1.15rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.student-card::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 4px;
  height: 100%;
  border-radius: 0 var(--radius) var(--radius) 0;
  transition: var(--transition);
}

.student-card.paid::before {
  background: var(--success);
}

.student-card.unpaid::before {
  background: var(--danger);
}

.student-card.partial::before {
  background: var(--warning);
}

.student-card.no-lessons::before {
  background: var(--text-muted);
}

.student-card:hover {
  background: var(--bg-card-hover);
  transform: translateX(-2px);
  border-color: rgba(255, 255, 255, 0.2);
}

.student-card:active {
  transform: scale(0.98);
}

.student-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.65rem;
}

.student-name {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
}

.student-badge {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
  text-transform: uppercase;
}

.badge-paid {
  background: var(--success-bg);
  color: var(--success);
}

.badge-unpaid {
  background: var(--danger-bg);
  color: var(--danger);
}

.badge-partial {
  background: var(--warning-bg);
  color: var(--warning);
}

.badge-none {
  background: rgba(106, 106, 142, 0.15);
  color: var(--text-muted);
}

.student-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
}

.student-stat {
  text-align: center;
}

.student-stat-value {
  display: block;
  font-size: 1rem;
  font-weight: 600;
}

.student-stat-label {
  display: block;
  font-size: 0.65rem;
  color: var(--text-muted);
  margin-top: 1px;
}

.student-card .btn-pay {
  margin-top: 0.75rem;
  width: 100%;
  background: rgba(108, 92, 231, 0.2);
  border: 1px solid rgba(108, 92, 231, 0.3);
  color: var(--accent-light);
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.student-card .btn-pay:hover {
  background: rgba(108, 92, 231, 0.35);
}

/* ====== EMPTY STATE ====== */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-secondary);
  position: relative;
  z-index: 1;
}

.empty-icon {
  font-size: 3rem;
  margin-bottom: 0.75rem;
}

.empty-hint {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* ====== BUTTONS ====== */
.btn-add {
  width: auto;
  min-width: 40px;
  height: 40px;
  padding: 0 1rem;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), #5a4bd1);
  border: none;
  color: white;
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.btn-add:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 24px var(--accent-glow);
}

.btn-add:active {
  transform: scale(0.95);
}

.btn {
  padding: 0.7rem 1.5rem;
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  border: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #5a4bd1);
  color: white;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 24px var(--accent-glow);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border-glass);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
}

.btn-danger {
  background: linear-gradient(135deg, var(--danger), #e55656);
  color: white;
}

.btn-delete-text {
  display: block;
  width: 100%;
  margin-top: 1rem;
  background: none;
  border: none;
  color: var(--danger);
  font-family: var(--font);
  font-size: 0.85rem;
  text-decoration: underline;
  cursor: pointer;
  opacity: 0.7;
  transition: var(--transition);
}

.btn-delete-text:hover {
  opacity: 1;
}

.btn-icon {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  padding: 0.25rem;
  transition: var(--transition);
}

.btn-icon:hover {
  transform: scale(1.2);
}

.close-btn-highlight {
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
}

.btn-delete-student {
  color: var(--danger) !important;
  font-size: 0.75rem !important;
  font-weight: 600;
  font-family: var(--font);
  background: var(--danger-bg) !important;
  border: 1px solid rgba(255, 107, 107, 0.3) !important;
  border-radius: 20px !important;
  padding: 0.25rem 0.7rem !important;
  cursor: pointer;
  transition: var(--transition);
}

.btn-delete-student:hover {
  background: rgba(255, 107, 107, 0.3) !important;
  transform: scale(1.05) !important;
}

/* ====== MODALS ====== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.modal {
  width: 100%;
  max-width: 400px;
  padding: 1.5rem;
  animation: slideUp 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.modal-large {
  max-width: 500px;
  max-height: 85vh;
  overflow-y: auto;
}

.modal-small {
  max-width: 320px;
  text-align: center;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.modal h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

.modal p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
  font-weight: 500;
}

.form-group input {
  width: 100%;
  padding: 0.7rem 0.9rem;
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 1rem;
  transition: var(--transition);
  direction: rtl;
}

.form-group input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

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

.modal-actions {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.modal-actions .btn {
  flex: 1;
}

/* ====== DETAIL MODAL ====== */
.detail-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.detail-actions {
  display: flex;
  gap: 0.5rem;
}

.detail-summary {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
  margin-bottom: 1.25rem;
  padding: 0.75rem;
  background: rgba(255, 255, 255, 0.04);
  border-radius: var(--radius-sm);
}

.detail-stat {
  text-align: center;
}

.detail-stat-value {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
}

.detail-stat-label {
  display: block;
  font-size: 0.7rem;
  color: var(--text-muted);
}

#detail-content h4 {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  margin-top: 0.75rem;
}

.detail-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.detail-list-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0.75rem;
  background: rgba(255, 255, 255, 0.04);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
}

.detail-list-item .date {
  color: var(--text-secondary);
}

.detail-list-item .amount {
  font-weight: 600;
}

.detail-list-item .btn-delete {
  background: none;
  border: none;
  color: var(--danger);
  font-size: 0.9rem;
  cursor: pointer;
  opacity: 0.6;
  transition: var(--transition);
  padding: 0 0.25rem;
}

.detail-list-item .btn-delete:hover {
  opacity: 1;
}

.detail-list-empty {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  padding: 0.75rem;
}

/* ====== TOAST ====== */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(120px);
  background: var(--bg-secondary);
  border: 1px solid var(--border-glass);
  color: var(--text-primary);
  padding: 0.75rem 1.5rem;
  border-radius: 30px;
  font-size: 0.85rem;
  font-weight: 500;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  z-index: 2000;
  transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  pointer-events: none;
  white-space: nowrap;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
}

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

.toast.error {
  border-color: var(--danger);
}

/* ====== INACTIVE STUDENT ====== */
.student-card.inactive {
  opacity: 0.5;
}

.quick-btn.inactive {
  display: none;
}

/* ====== RESPONSIVE ====== */
@media (min-width: 600px) {
  .students-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
  }

  .quick-log-grid {
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  }
}

@media (min-width: 900px) {
  body {
    max-width: 800px;
    margin: 0 auto;
  }
}

/* ====== SCROLLBAR ====== */
::-webkit-scrollbar {
  width: 4px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--border-glass);
  border-radius: 4px;
}

/* --- Login Modal Styles --- */
.login-modal {
  max-width: 320px;
  text-align: center;
  padding: 2.5rem 2rem;
  animation: modalFadeIn 0.3s ease-out;
}

.login-header {
  margin-bottom: 2rem;
}

.login-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.login-header h2 {
  margin: 0;
  color: var(--primary);
  font-size: 1.5rem;
}

.login-header p {
  margin: 0.5rem 0 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

#login-code {
  text-align: center;
  font-size: 1.2rem;
  letter-spacing: 0.5rem;
  padding: 1rem;
  background: rgba(255, 255, 255, 0.05);
}

.login-error-msg {
  color: #ff7675;
  font-size: 0.85rem;
  margin-top: 0.5rem;
  margin-bottom: 1rem;
}

.btn-block {
  width: 100%;
  margin-top: 1rem;
  padding: 1rem;
}

@keyframes modalFadeIn {
  from { opacity: 0; transform: translateY(-30px); }
  to { opacity: 1; transform: translateY(0); }
}