/* ============================================================================
   Hämeenkyrön Lentokerho - Main Stylesheet
   Production-ready CSS for the Finnish paragliding training club SPA
   ============================================================================ */

/* COLOR PALETTE */
:root {
  --color-dark-blue: #1A3A5C;
  --color-medium-blue: #2E6DA4;
  --color-light-blue: #D6E8F7;
  --color-red-brand: #CC0000;
  --color-light-gray: #F2F5F9;
  --color-white: #FFFFFF;
  --color-text-primary: #1F2937;
  --color-text-secondary: #6B7280;
  --color-border: #E5E7EB;
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-error: #EF4444;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;

  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
}

/* ============================================================================
   RESET & BASE STYLES
   ============================================================================ */

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--color-light-gray);
  color: var(--color-text-primary);
  line-height: 1.6;
  font-size: 16px;
}

a {
  color: var(--color-medium-blue);
  text-decoration: none;
  transition: color var(--transition-base);
}

a:hover {
  color: var(--color-dark-blue);
}

/* ============================================================================
   HEADER
   ============================================================================ */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  background-color: var(--color-dark-blue);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--spacing-lg);
  box-shadow: var(--shadow-md);
  z-index: 100;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  gap: var(--spacing-md);
}

.logo-section {
  display: flex;
  align-items: center;
  min-width: 0;
  flex: 1;
}

.header-brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  font-size: 20px;
  font-weight: 600;
  min-width: 220px;
}

.header-brand-logo {
  width: 36px;
  height: 36px;
  background-color: var(--color-red-brand);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 18px;
}

.header-brand-text {
  white-space: nowrap;
}

.header-user-section {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.user-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 14px;
}

.user-name {
  font-weight: 500;
}

.user-role {
  font-size: 12px;
  opacity: 0.8;
}

.btn-logout {
  padding: var(--spacing-sm) var(--spacing-md);
  background-color: var(--color-red-brand);
  color: var(--color-white);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: background-color var(--transition-base);
}

.btn-logout:hover {
  background-color: #B30000;
}

.btn-menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-white);
  font-size: 28px;
  line-height: 1;
  cursor: pointer;
  padding: 8px 12px;
  margin-right: 8px;
}

.sidebar-backdrop {
  display: none;
  position: fixed;
  inset: 56px 0 0 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 98;
}

.sidebar-backdrop.visible {
  display: block;
}

/* ============================================================================
   SIDEBAR / NAVIGATION
   ============================================================================ */

.sidebar {
  position: fixed;
  left: 0;
  top: 56px;
  width: 220px;
  height: calc(100vh - 56px);
  background-color: var(--color-white);
  border-right: 1px solid var(--color-border);
  padding: var(--spacing-lg) 0;
  overflow-y: auto;
  z-index: 99;
}

.sidebar.hidden {
  display: none;
}

.nav-section {
  margin-bottom: var(--spacing-lg);
}

.nav-section-title {
  padding: 0 var(--spacing-md);
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  letter-spacing: 0.5px;
  margin-bottom: var(--spacing-md);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  color: var(--color-text-primary);
  border-left: 3px solid transparent;
  transition: all var(--transition-base);
  cursor: pointer;
}

.nav-link:hover {
  background-color: var(--color-light-gray);
}

.nav-link.active {
  border-left-color: var(--color-medium-blue);
  background-color: var(--color-light-blue);
  color: var(--color-dark-blue);
  font-weight: 500;
}

.nav-icon {
  font-size: 20px;
  width: 24px;
  text-align: center;
  flex-shrink: 0;
}

/* ============================================================================
   MAIN CONTENT AREA
   ============================================================================ */

.main-content {
  margin-left: 220px;
  margin-top: 56px;
  padding: var(--spacing-lg);
  min-height: calc(100vh - 56px);
  background-color: var(--color-light-gray);
}

.page-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
  color: var(--color-dark-blue);
}

.page-subtitle {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-lg);
}

/* ============================================================================
   CARDS & CONTAINERS
   ============================================================================ */

.card {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: var(--spacing-lg);
  transition: box-shadow var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-md);
  padding-bottom: var(--spacing-md);
  border-bottom: 1px solid var(--color-border);
}

.card-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-dark-blue);
}

.card-body {
  color: var(--color-text-primary);
}

.card-footer {
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  display: flex;
  gap: var(--spacing-md);
  justify-content: flex-end;
}

/* Student Card */
.student-card {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}

.student-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--spacing-md);
}

.student-info {
  flex: 1;
}

.student-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-dark-blue);
  margin-bottom: var(--spacing-xs);
}

.student-meta {
  font-size: 13px;
  color: var(--color-text-secondary);
}

.student-progress-section {
  margin-top: var(--spacing-md);
}

.progress-label {
  font-size: 12px;
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xs);
  display: block;
}

/* Badges */
.badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.badge-ongoing {
  background-color: var(--color-light-blue);
  color: var(--color-dark-blue);
}

.badge-graduated {
  background-color: #D1FAE5;
  color: #065F46;
}

.badge-inactive {
  background-color: #FEE2E2;
  color: #991B1B;
}

.badge-warning {
  background-color: #FEF3C7;
  color: #92400E;
}

/* ============================================================================
   FORMS & INPUTS
   ============================================================================ */

.form-group {
  margin-bottom: var(--spacing-lg);
  display: flex;
  flex-direction: column;
}

.form-label {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-sm);
}

.form-label.required::after {
  content: " *";
  color: var(--color-error);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--spacing-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: 14px;
  color: var(--color-text-primary);
  background-color: var(--color-white);
  transition: all var(--transition-base);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-medium-blue);
  box-shadow: 0 0 0 3px rgba(46, 109, 164, 0.1);
}

.form-input:disabled,
.form-select:disabled {
  background-color: var(--color-light-gray);
  color: var(--color-text-secondary);
  cursor: not-allowed;
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.form-hint {
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-top: var(--spacing-xs);
}

.form-error {
  font-size: 12px;
  color: var(--color-error);
  margin-top: var(--spacing-xs);
}

.form-input.error,
.form-select.error {
  border-color: var(--color-error);
}

.form-checkbox {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  user-select: none;
}

.form-checkbox input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--color-medium-blue);
}

/* ============================================================================
   BUTTONS
   ============================================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  white-space: nowrap;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--color-medium-blue);
  color: var(--color-white);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-dark-blue);
  box-shadow: var(--shadow-md);
}

.btn-primary:active:not(:disabled) {
  transform: scale(0.98);
}

.btn-secondary {
  background-color: var(--color-light-gray);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-white);
  border-color: var(--color-medium-blue);
  color: var(--color-medium-blue);
}

.btn-danger {
  background-color: var(--color-error);
  color: var(--color-white);
}

.btn-danger:hover:not(:disabled) {
  background-color: #DC2626;
  box-shadow: var(--shadow-md);
}

.btn-success {
  background-color: var(--color-success);
  color: var(--color-white);
}

.btn-success:hover:not(:disabled) {
  background-color: #059669;
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background-color: transparent;
  color: var(--color-medium-blue);
  border: 2px solid var(--color-medium-blue);
}

.btn-outline:hover:not(:disabled) {
  background-color: var(--color-light-blue);
}

.btn-sm {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 13px;
}

.btn-lg {
  padding: var(--spacing-lg) var(--spacing-xl);
  font-size: 16px;
  font-weight: 700;
}

.btn-block {
  width: 100%;
}

.btn-loading::after {
  content: "";
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

/* ============================================================================
   TABLES
   ============================================================================ */

.table-container {
  overflow-x: auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  background-color: var(--color-white);
}

thead {
  background-color: var(--color-dark-blue);
  color: var(--color-white);
}

th {
  padding: var(--spacing-md);
  text-align: left;
  font-weight: 600;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

td {
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--color-border);
  font-size: 14px;
}

tbody tr:hover {
  background-color: var(--color-light-gray);
}

tbody tr:nth-child(even) {
  background-color: rgba(242, 245, 249, 0.5);
}

.table-actions {
  display: flex;
  gap: var(--spacing-sm);
}

/* ============================================================================
   PROGRESS BARS
   ============================================================================ */

.progress-bar {
  width: 100%;
  height: 8px;
  background-color: var(--color-border);
  border-radius: 4px;
  overflow: hidden;
  margin-top: var(--spacing-sm);
}

.progress-fill {
  height: 100%;
  background-color: var(--color-medium-blue);
  border-radius: 4px;
  transition: width var(--transition-base);
  animation: pulse-width 1s ease-in-out;
}

.progress-fill.complete {
  background-color: var(--color-success);
}

.progress-fill.warning {
  background-color: var(--color-warning);
}

.progress-fill.error {
  background-color: var(--color-error);
}

@keyframes pulse-width {
  0% {
    width: 0;
  }
}

.progress-container {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.progress-text {
  font-size: 13px;
  color: var(--color-text-secondary);
  min-width: 45px;
  text-align: right;
}

/* ============================================================================
   THEORY SECTION / COLLAPSIBLES
   ============================================================================ */

.theory-section {
  margin-bottom: var(--spacing-md);
}

.theory-item {
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-md);
  overflow: hidden;
}

details {
  cursor: pointer;
}

summary {
  padding: var(--spacing-md) var(--spacing-lg);
  background-color: var(--color-light-gray);
  font-weight: 600;
  color: var(--color-dark-blue);
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  transition: background-color var(--transition-base);
}

summary:hover {
  background-color: #E8ECF3;
}

summary::marker {
  color: var(--color-medium-blue);
}

.theory-content {
  padding: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

.theory-checklist {
  list-style: none;
  padding: 0;
  margin: 0;
}

.theory-item-check {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
  background-color: var(--color-light-gray);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}

.theory-item-check.done {
  background-color: #D1FAE5;
}

.theory-item-check.done .theory-item-text {
  text-decoration: line-through;
  color: var(--color-text-secondary);
}

.theory-item-check input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--color-success);
}

.theory-item-text {
  flex: 1;
  font-size: 14px;
  color: var(--color-text-primary);
}

/* ============================================================================
   ALERTS & NOTIFICATIONS
   ============================================================================ */

.alert {
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-lg);
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-md);
}

.alert-icon {
  font-size: 18px;
  flex-shrink: 0;
  margin-top: 2px;
}

.alert-content {
  flex: 1;
}

.alert-title {
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.alert-message {
  font-size: 14px;
  line-height: 1.5;
}

.alert-error {
  background-color: #FEE2E2;
  color: #991B1B;
  border-left: 4px solid var(--color-error);
}

.alert-success {
  background-color: #D1FAE5;
  color: #065F46;
  border-left: 4px solid var(--color-success);
}

.alert-warning {
  background-color: #FEF3C7;
  color: #92400E;
  border-left: 4px solid var(--color-warning);
}

.alert-info {
  background-color: var(--color-light-blue);
  color: var(--color-dark-blue);
  border-left: 4px solid var(--color-medium-blue);
}

.alert-close {
  background: none;
  border: none;
  color: inherit;
  cursor: pointer;
  font-size: 18px;
  padding: 0;
  flex-shrink: 0;
  opacity: 0.7;
  transition: opacity var(--transition-base);
}

.alert-close:hover {
  opacity: 1;
}

/* ============================================================================
   DASHBOARD
   ============================================================================ */

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.stat-card {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-sm);
  text-align: center;
  transition: all var(--transition-base);
}

.stat-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.stat-number {
  font-size: 32px;
  font-weight: 700;
  color: var(--color-medium-blue);
  margin-bottom: var(--spacing-sm);
}

.stat-label {
  font-size: 14px;
  color: var(--color-text-secondary);
  font-weight: 500;
}

.stat-trend {
  font-size: 12px;
  margin-top: var(--spacing-sm);
  font-weight: 600;
}

.stat-trend.positive {
  color: var(--color-success);
}

.stat-trend.negative {
  color: var(--color-error);
}

.warning-card {
  background-color: #FFFBEB;
  border-left: 4px solid var(--color-warning);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.warning-card-title {
  font-weight: 600;
  color: #92400E;
  margin-bottom: var(--spacing-sm);
}

.warning-card-message {
  font-size: 14px;
  color: #78350F;
  line-height: 1.5;
}

/* ============================================================================
   MODALS
   ============================================================================ */

#modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 200;
  padding: var(--spacing-md);
}

#modal-overlay.visible {
  display: flex;
}

.modal {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  max-width: 600px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  padding: var(--spacing-xl);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-lg);
  border-bottom: 1px solid var(--color-border);
}

.modal-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--color-dark-blue);
}

.modal-close-btn {
  background: none;
  border: none;
  font-size: 24px;
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}

.modal-close-btn:hover {
  background-color: var(--color-light-gray);
  color: var(--color-text-primary);
}

.modal-body {
  margin-bottom: var(--spacing-lg);
}

.modal-footer {
  display: flex;
  gap: var(--spacing-md);
  justify-content: flex-end;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

/* ============================================================================
   CALENDAR
   ============================================================================ */

.calendar-container {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-sm);
}

.calendar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
}

.calendar-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-dark-blue);
}

.calendar-nav {
  display: flex;
  gap: var(--spacing-md);
}

.calendar-nav-btn {
  padding: var(--spacing-sm) var(--spacing-md);
  background-color: var(--color-light-gray);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
}

.calendar-nav-btn:hover {
  background-color: var(--color-medium-blue);
  color: var(--color-white);
  border-color: var(--color-medium-blue);
}

.calendar {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: var(--spacing-sm);
}

.cal-weekday {
  text-align: center;
  font-weight: 600;
  color: var(--color-text-secondary);
  font-size: 12px;
  padding: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.cal-day {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  font-size: 14px;
  color: var(--color-text-primary);
  position: relative;
}

.cal-day:hover {
  background-color: var(--color-light-gray);
}

.cal-day.other-month {
  color: var(--color-text-secondary);
  background-color: #FAFAFA;
}

.cal-day.today {
  border: 2px solid var(--color-medium-blue);
  font-weight: 700;
}

.cal-day.has-flight {
  background-color: var(--color-light-blue);
  font-weight: 600;
  color: var(--color-dark-blue);
}

.cal-day.has-flight::after {
  content: "";
  position: absolute;
  bottom: 2px;
  width: 6px;
  height: 6px;
  background-color: var(--color-medium-blue);
  border-radius: 50%;
}

.cal-day.selected {
  background-color: var(--color-medium-blue);
  color: var(--color-white);
}

/* ============================================================================
   LOGIN PAGE
   ============================================================================ */

.login-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: url('/bg-login.jpg') center center / cover no-repeat,
              linear-gradient(135deg, var(--color-dark-blue) 0%, var(--color-medium-blue) 100%);
  padding: var(--spacing-md);
  position: relative;
}

.login-container::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.15);
  z-index: 0;
}

.login-card {
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: var(--radius-lg);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  padding: var(--spacing-xl);
  max-width: 400px;
  width: 100%;
  position: relative;
  z-index: 1;
}

.login-header {
  text-align: center;
  margin-bottom: var(--spacing-lg);
}

.login-logo {
  width: 56px;
  height: 56px;
  background-color: var(--color-red-brand);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--spacing-md);
  font-size: 32px;
  font-weight: 700;
  color: var(--color-white);
}

.login-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-dark-blue);
  margin-bottom: var(--spacing-sm);
}

.login-subtitle {
  font-size: 14px;
  color: var(--color-text-secondary);
}

.login-form {
  margin-top: var(--spacing-lg);
}

.login-submit {
  width: 100%;
  margin-top: var(--spacing-lg);
}

.login-error {
  background-color: #FEE2E2;
  color: #991B1B;
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-lg);
  font-size: 14px;
  border-left: 4px solid var(--color-error);
}

.login-footer {
  text-align: center;
  margin-top: var(--spacing-lg);
  font-size: 12px;
  color: var(--color-text-secondary);
}

/* ============================================================================
   EMPTY STATES
   ============================================================================ */

.empty-state {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--color-text-secondary);
}

.empty-icon {
  font-size: 48px;
  margin-bottom: var(--spacing-md);
  opacity: 0.5;
}

.empty-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-sm);
}

.empty-message {
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: var(--spacing-lg);
}

/* ============================================================================
   GRID LAYOUTS
   ============================================================================ */

.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

.flex-row {
  display: flex;
  gap: var(--spacing-md);
}

.flex-column {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.justify-between {
  justify-content: space-between;
}

.align-center {
  align-items: center;
}

.gap-sm {
  gap: var(--spacing-sm);
}

.gap-md {
  gap: var(--spacing-md);
}

.gap-lg {
  gap: var(--spacing-lg);
}

/* ============================================================================
   SPACING UTILITIES
   ============================================================================ */

.mt-sm {
  margin-top: var(--spacing-sm);
}

.mt-md {
  margin-top: var(--spacing-md);
}

.mt-lg {
  margin-top: var(--spacing-lg);
}

.mb-sm {
  margin-bottom: var(--spacing-sm);
}

.mb-md {
  margin-bottom: var(--spacing-md);
}

.mb-lg {
  margin-bottom: var(--spacing-lg);
}

.px-lg {
  padding-left: var(--spacing-lg);
  padding-right: var(--spacing-lg);
}

.py-lg {
  padding-top: var(--spacing-lg);
  padding-bottom: var(--spacing-lg);
}

/* ============================================================================
   ANIMATIONS
   ============================================================================ */

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes slide-in {
  from {
    transform: translateY(-10px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.fade-in {
  animation: fade-in var(--transition-base);
}

.slide-in {
  animation: slide-in var(--transition-base);
}

/* ============================================================================
   RESPONSIVE DESIGN
   ============================================================================ */

@media (max-width: 1024px) {
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }

  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  /* Header adjustments for mobile */
  .header {
    padding: 0 var(--spacing-sm);
  }

  .btn-menu-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .brand-text {
    font-size: 15px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  /* Sidebar hidden on mobile, slides in when .visible */
  .sidebar {
    transform: translateX(-100%);
    transition: transform var(--transition-base);
    width: 260px;
    box-shadow: var(--shadow-lg);
  }

  .sidebar.visible {
    transform: translateX(0);
  }

  /* Main content full width */
  .main-content {
    margin-left: 0;
    padding: var(--spacing-md);
  }

  /* Larger tap targets in nav */
  .sidebar-nav a {
    padding: 14px 18px;
    font-size: 16px;
  }

  /* Stackable flight rows */
  .mobile-stack thead {
    display: none;
  }
  .mobile-stack, .mobile-stack tbody, .mobile-stack tr, .mobile-stack td {
    display: block;
    width: 100%;
  }
  .mobile-stack tr {
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 10px 12px;
    margin-bottom: 10px;
    background: #fff;
  }
  .mobile-stack td {
    padding: 4px 0 !important;
    border: none !important;
  }
  .mobile-stack td[data-label]::before {
    content: attr(data-label) ": ";
    font-weight: 600;
    color: #555;
    margin-right: 6px;
  }
  .mobile-stack td[data-label="Päivä"]::before,
  .mobile-stack td[data-label="Toiminnot"]::before {
    content: none;
  }
  .mobile-stack td[data-label="Päivä"] {
    font-weight: 600;
    font-size: 1.05em;
    margin-bottom: 4px;
  }

  /* Grid adjustments */
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .grid-4,
  .grid-3,
  .grid-2 {
    grid-template-columns: 1fr;
  }

  /* Button sizing */
  .btn {
    padding: var(--spacing-md) var(--spacing-md);
  }

  .btn-lg {
    width: 100%;
  }

  /* Card padding */
  .card {
    padding: var(--spacing-md);
  }

  /* Form group adjustments */
  .form-group {
    margin-bottom: var(--spacing-md);
  }

  /* Table responsiveness */
  .table-container {
    overflow-x: auto;
  }

  table {
    font-size: 13px;
  }

  th,
  td {
    padding: var(--spacing-sm);
  }

  /* Modal adjustments */
  .modal {
    margin: var(--spacing-md);
    max-height: calc(100vh - 32px);
  }

  .page-title {
    font-size: 22px;
  }

  .header-brand {
    min-width: auto;
  }

  .header-brand-text {
    display: none;
  }
}

@media (max-width: 480px) {
  :root {
    font-size: 15px;
  }

  .page-title {
    font-size: 20px;
    margin-bottom: var(--spacing-md);
  }

  .card,
  .student-card {
    padding: var(--spacing-md);
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .login-card {
    padding: var(--spacing-lg);
  }

  .modal {
    padding: var(--spacing-lg);
  }

  .flex-row {
    flex-direction: column;
  }

  .btn {
    padding: var(--spacing-md);
    width: 100%;
  }

  .card-footer,
  .modal-footer {
    flex-direction: column;
  }

  .btn-sm {
    width: 100%;
  }

  table {
    font-size: 12px;
  }

  th,
  td {
    padding: 8px 4px;
  }
}

/* ============================================================================
   PRINT STYLES
   ============================================================================ */

@media print {
  .header,
  .sidebar,
  .btn-menu-toggle,
  .modal-footer {
    display: none;
  }

  .main-content {
    margin: 0;
    padding: 0;
  }

  .card,
  .student-card {
    page-break-inside: avoid;
    box-shadow: none;
    border: 1px solid var(--color-border);
  }

  body {
    background: var(--color-white);
  }

  a {
    color: var(--color-medium-blue);
    text-decoration: underline;
  }

  .alert {
    border: 1px solid var(--color-border);
  }
}

/* ============================================================================
   UTILITY CLASSES
   ============================================================================ */

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

.text-right {
  text-align: right;
}

.text-left {
  text-align: left;
}

.text-muted {
  color: var(--color-text-secondary);
}

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

.text-success {
  color: var(--color-success);
}

.text-warning {
  color: var(--color-warning);
}

.font-bold {
  font-weight: 700;
}

.font-semibold {
  font-weight: 600;
}

.font-normal {
  font-weight: 400;
}

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.cursor-pointer {
  cursor: pointer;
}

.cursor-not-allowed {
  cursor: not-allowed;
}

.opacity-50 {
  opacity: 0.5;
}

.opacity-75 {
  opacity: 0.75;
}

.visibility-hidden {
  visibility: hidden;
}

.hidden {
  display: none !important;
}

.block {
  display: block;
}

.inline-block {
  display: inline-block;
}

.flex {
  display: flex;
}

.rounded {
  border-radius: var(--radius-md);
}

.rounded-lg {
  border-radius: var(--radius-lg);
}

.bg-white {
  background-color: var(--color-white);
}

.bg-light {
  background-color: var(--color-light-gray);
}

.bg-blue {
  background-color: var(--color-light-blue);
}

.border {
  border: 1px solid var(--color-border);
}

.border-t {
  border-top: 1px solid var(--color-border);
}

.border-b {
  border-bottom: 1px solid var(--color-border);
}

.shadow {
  box-shadow: var(--shadow-md);
}

.shadow-sm {
  box-shadow: var(--shadow-sm);
}

.shadow-lg {
  box-shadow: var(--shadow-lg);
}

/* ============================================================================
   END OF STYLESHEET
   ============================================================================ */