/*--------------------------------------------------------------
# Browser Fallbacks and Cross-Browser Compatibility
# Requirements: 4.1, 4.2, 4.3 - Cross-browser compatibility
--------------------------------------------------------------*/

/*--------------------------------------------------------------
# Internet Explorer Fallbacks
--------------------------------------------------------------*/

/* IE 11 and below fallbacks */
.ie-browser .partners-grid {
  /* Fallback to flexbox for IE */
  display: -ms-flexbox;
  display: flex;
  -ms-flex-wrap: wrap;
  flex-wrap: wrap;
  -ms-flex-pack: center;
  justify-content: center;
}

.ie-browser .partner-card {
  /* Fixed width for IE flexbox */
  width: calc(33.333% - 20px);
  margin: 10px;
  -ms-flex: 0 0 auto;
  flex: 0 0 auto;
}

.ie-browser .filter-tabs {
  /* IE flexbox fallback */
  display: -ms-flexbox;
  display: flex;
  -ms-flex-wrap: wrap;
  flex-wrap: wrap;
  -ms-flex-pack: center;
  justify-content: center;
}

.ie-browser .filter-tab {
  /* Remove modern CSS features for IE */
  border-radius: 25px; /* Fallback from 50px */
  transition: all 0.3s ease; /* Simplified transition */
}

.ie-browser .filter-tab::before {
  /* Remove pseudo-element animations for IE */
  display: none;
}

.ie-browser .partner-search {
  /* Simplified styling for IE */
  border-radius: 25px;
  padding: 14px 45px 14px 18px;
}

/* IE Custom Properties Fallback */
.ie-browser .filter-tab {
  background: #ffffff;
  border: 2px solid rgba(0, 160, 223, 0.15);
  color: #373f47;
}

.ie-browser .filter-tab.active {
  background: #00a0df;
  border-color: #00a0df;
  color: #ffffff;
}

.ie-browser .partner-card {
  background-color: #ffffff;
  border: 1px solid #00a0df;
}

.ie-browser .partner-search {
  background: #ffffff;
  color: #373f47;
  border: 2px solid rgba(0, 160, 223, 0.15);
}

/*--------------------------------------------------------------
# Safari Fallbacks
--------------------------------------------------------------*/

.safari-browser .filter-tabs {
  /* Safari scrollbar styling */
  -webkit-overflow-scrolling: touch;
}

.safari-browser .filter-tabs::-webkit-scrollbar {
  height: 4px;
}

.safari-browser .filter-tabs::-webkit-scrollbar-track {
  background: rgba(0, 160, 223, 0.1);
  border-radius: 2px;
}

.safari-browser .filter-tabs::-webkit-scrollbar-thumb {
  background: rgba(0, 160, 223, 0.3);
  border-radius: 2px;
}

.safari-browser .filter-tabs::-webkit-scrollbar-thumb:hover {
  background: rgba(0, 160, 223, 0.5);
}

/* Safari transform optimization */
.safari-browser .partner-card {
  -webkit-transform: translateZ(0);
  transform: translateZ(0);
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
}

/* Safari focus improvements */
.safari-browser .filter-tab:focus,
.safari-browser .partner-search:focus {
  outline: 2px solid rgba(0, 160, 223, 0.8);
  outline-offset: 2px;
}

/*--------------------------------------------------------------
# Firefox Fallbacks
--------------------------------------------------------------*/

.firefox-browser .filter-tabs {
  /* Firefox scrollbar styling */
  scrollbar-width: thin;
  scrollbar-color: rgba(0, 160, 223, 0.3) transparent;
}

/* Firefox focus outline improvements */
.firefox-browser .filter-tab:focus,
.firefox-browser .partner-search:focus {
  outline: 2px solid rgba(0, 160, 223, 0.8);
  outline-offset: 2px;
}

/* Firefox animation optimization */
.firefox-browser .partner-card {
  will-change: auto; /* Prevent excessive layer creation */
}

/*--------------------------------------------------------------
# Mobile Browser Fallbacks
--------------------------------------------------------------*/

.mobile-browser .filter-tab,
.mobile-browser .partner-search,
.mobile-browser .search-clear {
  /* Improve touch responsiveness */
  touch-action: manipulation;
  -webkit-tap-highlight-color: rgba(0, 160, 223, 0.2);
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.mobile-browser .partner-search {
  /* Prevent zoom on focus for iOS */
  font-size: 16px;
}

/* iOS Safari specific fixes */
.mobile-browser.safari-browser .partner-card {
  /* Fix for iOS Safari rendering issues */
  -webkit-transform: translate3d(0, 0, 0);
  transform: translate3d(0, 0, 0);
}

/*--------------------------------------------------------------
# CSS Grid Fallbacks
--------------------------------------------------------------*/

/* Fallback for browsers without CSS Grid support */
@supports not (display: grid) {
  .partners-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: stretch;
  }
  
  .partner-card {
    width: calc(33.333% - 20px);
    margin: 10px;
    flex: 0 0 auto;
  }
  
  /* Responsive fallbacks */
  @media (max-width: 991px) {
    .partner-card {
      width: calc(50% - 20px);
    }
  }
  
  @media (max-width: 767px) {
    .partner-card {
      width: calc(100% - 20px);
    }
  }
}

/*--------------------------------------------------------------
# Flexbox Fallbacks
--------------------------------------------------------------*/

/* Fallback for browsers without Flexbox support */
@supports not (display: flex) {
  .filter-tabs {
    text-align: center;
  }
  
  .filter-tab {
    display: inline-block;
    margin: 5px;
    vertical-align: top;
  }
  
  .search-container {
    text-align: center;
    margin: 20px auto;
    width: 400px;
    max-width: 100%;
  }
  
  .partners-grid {
    text-align: center;
  }
  
  .partner-card {
    display: inline-block;
    width: 300px;
    margin: 15px;
    vertical-align: top;
    text-align: left;
  }
}

/*--------------------------------------------------------------
# CSS Custom Properties Fallbacks
--------------------------------------------------------------*/

/* Fallback colors for browsers without custom properties support */
@supports not (color: var(--test)) {
  .filter-tab {
    background: #ffffff;
    border: 2px solid rgba(0, 160, 223, 0.15);
    color: #373f47;
  }
  
  .filter-tab.active {
    background: #00a0df;
    border-color: #00a0df;
    color: #ffffff;
  }
  
  .partner-card {
    background-color: #ffffff;
    border: 1px solid #00a0df;
  }
  
  .partner-expertise {
    color: #373f47;
  }
  
  .partner-description {
    color: #6c757d;
  }
  
  .partner-search {
    background: #ffffff;
    color: #373f47;
    border: 2px solid rgba(0, 160, 223, 0.15);
  }
  
  .partner-search::placeholder {
    color: rgba(55, 63, 71, 0.5);
  }
}

/*--------------------------------------------------------------
# Transform and Animation Fallbacks
--------------------------------------------------------------*/

/* Fallback for browsers without transform support */
@supports not (transform: translateY(0)) {
  .partner-card.filtered-out {
    display: none;
  }
  
  .partner-card.filtering-out {
    display: none;
  }
  
  .partner-card.filtering-in {
    display: block;
  }
  
  .filter-tab:hover {
    background: rgba(0, 160, 223, 0.1);
  }
}

/* Fallback for browsers without transition support */
@supports not (transition: opacity 0.3s) {
  .partner-card,
  .filter-tab,
  .partner-search {
    /* Remove all transitions for unsupported browsers */
  }
  
  .partner-card:hover {
    background: #f8f9fa;
  }
  
  .filter-tab:hover {
    background: rgba(0, 160, 223, 0.1);
  }
}

/*--------------------------------------------------------------
# Reduced Motion Support
--------------------------------------------------------------*/

/* Respect user's motion preferences */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  
  .partner-card.animate-in {
    animation: none;
    opacity: 1;
    transform: none;
  }
  
  .filter-tabs {
    animation: none;
    opacity: 1;
    transform: none;
  }
  
  .search-container {
    animation: none;
    opacity: 1;
    transform: none;
  }
}

/*--------------------------------------------------------------
# High Contrast Mode Support
--------------------------------------------------------------*/

@media (prefers-contrast: high) {
  .filter-tab {
    border-width: 3px;
    font-weight: 600;
  }
  
  .filter-tab.active {
    border-width: 4px;
  }
  
  .partner-card {
    border-width: 2px;
  }
  
  .partner-search {
    border-width: 3px;
  }
  
  .partner-logo img {
    filter: contrast(1.2);
  }
}

/*--------------------------------------------------------------
# Print Styles
--------------------------------------------------------------*/

@media print {
  .partner-filters {
    display: none;
  }
  
  .partner-card {
    break-inside: avoid;
    page-break-inside: avoid;
    margin-bottom: 20px;
    border: 2px solid #000;
    background: white !important;
  }
  
  .partner-card:hover:before {
    display: none;
  }
  
  .partner-expertise,
  .partner-description {
    color: #000 !important;
  }
  
  .partner-logo img {
    filter: grayscale(100%);
  }
}

/*--------------------------------------------------------------
# Slow Device Optimizations
--------------------------------------------------------------*/

.slow-loading .partner-card {
  transition: opacity 0.2s ease !important;
  animation: none !important;
}

.slow-loading .filter-tab::before {
  display: none !important;
}

.slow-loading .partner-logo img {
  transition: none !important;
}

.slow-interaction .partner-search {
  transition: border-color 0.1s ease !important;
}

.reduced-animations .partner-card,
.reduced-animations .filter-tab {
  animation: none !important;
  transition: opacity 0.1s ease !important;
}

/*--------------------------------------------------------------
# Breakpoint-Specific Optimizations
--------------------------------------------------------------*/

.breakpoint-xs .partners-grid {
  grid-template-columns: 1fr !important;
  gap: 15px !important;
}

.breakpoint-sm .partners-grid {
  grid-template-columns: 1fr !important;
  gap: 18px !important;
}

.breakpoint-md .partners-grid {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)) !important;
  gap: 20px !important;
}

.breakpoint-lg .partners-grid {
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)) !important;
  gap: 24px !important;
}

.breakpoint-xl .partners-grid {
  grid-template-columns: repeat(auto-fit, minmax(380px, 1fr)) !important;
  gap: 28px !important;
}

/*--------------------------------------------------------------
# Error State Fallbacks
--------------------------------------------------------------*/

.partners-grid.error {
  position: relative;
  min-height: 200px;
}

.partners-grid.error::before {
  content: 'Filtering system unavailable. All partners are shown below.';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  background: #fff3cd;
  color: #856404;
  padding: 16px;
  border-radius: 8px;
  text-align: center;
  border: 1px solid #ffeaa7;
  margin-bottom: 20px;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

.filter-tab.error {
  background: #f8d7da !important;
  border-color: #f5c6cb !important;
  color: #721c24 !important;
  cursor: not-allowed;
}

.search-container.error .partner-search {
  border-color: #dc3545 !important;
  background: #fff5f5 !important;
}

/*--------------------------------------------------------------
# Legacy Browser Support (IE 9-10)
--------------------------------------------------------------*/

/* IE 9-10 specific fixes */
.lt-ie11 .partners-grid {
  display: block;
  text-align: center;
}

.lt-ie11 .partner-card {
  display: inline-block;
  width: 300px;
  margin: 15px;
  vertical-align: top;
  text-align: left;
}

.lt-ie11 .filter-tabs {
  text-align: center;
}

.lt-ie11 .filter-tab {
  display: inline-block;
  margin: 5px;
  border-radius: 15px; /* Reduced radius for IE 9-10 */
}

.lt-ie11 .partner-search {
  width: 300px;
  margin: 0 auto;
  display: block;
  border-radius: 15px;
}

/*--------------------------------------------------------------
# Feature Detection Classes
--------------------------------------------------------------*/

/* No JavaScript fallback */
.no-js .partner-filters {
  display: none;
}

.no-js .partner-card {
  display: block !important;
  opacity: 1 !important;
  transform: none !important;
  visibility: visible !important;
}

/* No CSS Grid fallback */
.no-cssgrid .partners-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

.no-cssgrid .partner-card {
  width: calc(33.333% - 20px);
  margin: 10px;
  flex: 0 0 auto;
}

/* No Flexbox fallback */
.no-flexbox .filter-tabs {
  text-align: center;
}

.no-flexbox .filter-tab {
  display: inline-block;
  margin: 5px;
}

.no-flexbox .partners-grid {
  text-align: center;
}

.no-flexbox .partner-card {
  display: inline-block;
  width: 300px;
  margin: 15px;
  vertical-align: top;
}

/*--------------------------------------------------------------
# Accessibility Enhancements for Older Browsers
--------------------------------------------------------------*/

/* Enhanced focus indicators for older browsers */
.filter-tab:focus,
.partner-search:focus,
.search-clear:focus {
  outline: 3px solid #00a0df;
  outline-offset: 2px;
}

/* High contrast focus for accessibility */
@media (-ms-high-contrast: active) {
  .filter-tab:focus,
  .partner-search:focus {
    outline: 3px solid;
  }
}

/* Windows High Contrast Mode */
@media (-ms-high-contrast: black-on-white) {
  .partner-card {
    border: 2px solid;
  }
  
  .filter-tab {
    border: 2px solid;
  }
}

@media (-ms-high-contrast: white-on-black) {
  .partner-card {
    border: 2px solid;
  }
  
  .filter-tab {
    border: 2px solid;
  }
}