/* Verb Tenses Slideshow Styles */

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

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

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
  color: #333;
  overflow: hidden;
  height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  margin: 0;
  padding: 0;
}

/* Header Styles */
.slideshow-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.98);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  z-index: 1000;
  padding: 0.75rem 2rem;
  box-shadow: 0 4px 32px rgba(0, 0, 0, 0.08);
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1400px;
  margin: 0 auto;
  height: 60px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: #2a5298;
  letter-spacing: -0.025em;
}

.brand i {
  font-size: 1.5rem;
  color: #667eea;
}

.presentation-controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.control-btn {
  background: #667eea;
  color: white;
  border: none;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-size: 0.875rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
}

.control-btn:hover {
  background: #5a67d8;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

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

/* Slideshow Container */
.slideshow-container {
  position: relative;
  height: 100vh;
  padding-top: 76px;
  overflow: hidden;
  width: 100%;
  cursor: default;
}

/* Click navigation zones for fullscreen */
.slideshow-container::before,
.slideshow-container::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 30%;
  z-index: 10;
  opacity: 0;
  transition: opacity 0.2s ease;
  pointer-events: none;
}

.slideshow-container::before {
  left: 0;
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0.05) 0%,
    transparent 100%
  );
}

.slideshow-container::after {
  right: 0;
  background: linear-gradient(
    -90deg,
    rgba(255, 255, 255, 0.05) 0%,
    transparent 100%
  );
}

:fullscreen .slideshow-container::before,
:fullscreen .slideshow-container::after {
  pointer-events: auto;
}

:fullscreen .slideshow-container:hover::before,
:fullscreen .slideshow-container:hover::after {
  opacity: 1;
}

/* Navigation hints for fullscreen */
:fullscreen .slideshow-container::before {
  cursor: url("data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMjQiIGhlaWdodD0iMjQiIHZpZXdCb3g9IjAgMCAyNCAyNCIgZmlsbD0ibm9uZSIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4KPHBhdGggZD0iTTE1IDZMMTAgMTJMMTUgMTgiIHN0cm9rZT0id2hpdGUiIHN0cm9rZS13aWR0aD0iMiIgc3Ryb2tlLWxpbmVjYXA9InJvdW5kIiBzdHJva2UtbGluZWpvaW49InJvdW5kIi8+Cjwvc3ZnPgo="),
    auto;
}

:fullscreen .slideshow-container::after {
  cursor: url("data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMjQiIGhlaWdodD0iMjQiIHZpZXdCb3g9IjAgMCAyNCAyNCIgZmlsbD0ibm9uZSIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4KPHBhdGggZD0iTTkgNkwxNCAxMkw5IDE4IiBzdHJva2U9IndoaXRlIiBzdHJva2Utd2lkdGg9IjIiIHN0cm9rZS1saW5lY2FwPSJyb3VuZCIgc3Ryb2tlLWxpbmVqb2luPSJyb3VuZCIvPgo8L3N2Zz4K"),
    auto;
}

/* Touch feedback for mobile devices */
@media (hover: none) and (pointer: coarse) {
  .slideshow-container::before,
  .slideshow-container::after {
    display: none;
  }

  :fullscreen .slideshow-container {
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    -webkit-touch-callout: none;
    touch-action: pan-y;
  }

  /* Enhanced touch zones for mobile */
  :fullscreen .slideshow-container::before,
  :fullscreen .slideshow-container::after {
    display: block;
    width: 35%;
    background: transparent;
    opacity: 1;
  }
}

/* Fullscreen styles */
:fullscreen .slideshow-header,
:fullscreen .progress-bar,
:fullscreen .slide-counter,
:fullscreen .timer-display,
:fullscreen .navigation-controls {
  display: none !important;
}

:fullscreen .slideshow-container {
  padding-top: 0;
  height: 100vh;
}

:fullscreen .slide {
  height: 100vh;
  padding: 1rem;
}

:fullscreen .slide-content {
  max-height: 100%;
  overflow-y: auto;
}

/* Additional fullscreen optimizations */
.fullscreen-mode .slide-content {
  max-width: 95vw;
  max-height: 95vh;
  margin: 2.5vh auto;
}

.fullscreen-mode .slide-content h1 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
}

.fullscreen-mode .slide-content h2 {
  font-size: 2rem;
  margin-bottom: 1.25rem;
}

.fullscreen-mode .slide-content h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

/* Fullscreen indicator overlay */
.fullscreen-mode::before {
  content: "Press ESC to exit fullscreen";
  position: fixed;
  top: 1rem;
  right: 1rem;
  background: rgba(0, 0, 0, 0.7);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  font-size: 0.875rem;
  z-index: 10000;
  pointer-events: none;
  opacity: 0;
  animation: fadeInOut 3s ease-in-out;
}

@keyframes fadeInOut {
  0%,
  100% {
    opacity: 0;
  }
  10%,
  90% {
    opacity: 1;
  }
}

/* Better utilization of screen space */
.slide {
  display: none;
  height: calc(100vh - 140px);
  padding: 1rem;
  animation: slideIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  width: 100%;
  box-sizing: border-box;
}

/* Progress Bar */
.progress-bar {
  position: fixed;
  top: 76px;
  left: 0;
  right: 0;
  height: 3px;
  background: rgba(255, 255, 255, 0.15);
  z-index: 999;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  width: 4%;
  border-radius: 0 2px 2px 0;
}

/* Slide Counter */
.slide-counter {
  position: fixed;
  top: 90px;
  right: 2rem;
  background: rgba(255, 255, 255, 0.95);
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: 600;
  color: #2a5298;
  z-index: 998;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  font-size: 0.875rem;
  border: 1px solid rgba(255, 255, 255, 0.3);
}

/* Timer Display */
.timer-display {
  position: fixed;
  top: 90px;
  left: 2rem;
  background: rgba(255, 255, 255, 0.95);
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: 600;
  color: #2a5298;
  z-index: 998;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  font-size: 0.875rem;
  border: 1px solid rgba(255, 255, 255, 0.3);
  display: none;
}

.timer-display.active {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Slide Styles */
.slide {
  display: none;
  height: calc(100vh - 140px);
  padding: 1rem;
  animation: slideIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  width: 100%;
  box-sizing: border-box;
}

.slide.active {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.slide-content {
  background: white;
  border-radius: 24px;
  padding: 2rem;
  margin: 0 auto;
  max-width: 1200px;
  width: 100%;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06), 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  min-height: 600px;
  max-height: calc(100vh - 200px);
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  position: relative;
  overflow-y: auto;
}

/* Fullscreen adjustments for slide content */
:fullscreen .slide-content {
  max-width: 95%;
  max-height: 95vh;
  margin: 2.5vh auto;
  border-radius: 16px;
  padding: 1.5rem;
}

.slide-content::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
  border-radius: 24px 24px 0 0;
}

/* Title Slide */
.title-slide {
  text-align: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  position: relative;
  overflow: hidden;
  border: none;
}

.title-slide::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, #4facfe 0%, #00f2fe 100%);
  border-radius: 24px 24px 0 0;
}

.title-slide::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(
      circle at 20% 80%,
      rgba(255, 255, 255, 0.1) 0%,
      transparent 50%
    ),
    radial-gradient(
      circle at 80% 20%,
      rgba(255, 255, 255, 0.1) 0%,
      transparent 50%
    );
  pointer-events: none;
}

.title-slide h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  margin-bottom: 1rem;
  position: relative;
  z-index: 1;
  letter-spacing: -0.025em;
  line-height: 1.1;
}

.title-slide h2 {
  font-size: clamp(1.25rem, 3vw, 2rem);
  font-weight: 400;
  margin-bottom: 2.5rem;
  opacity: 0.9;
  position: relative;
  z-index: 1;
  letter-spacing: -0.015em;
}

.timeline-visual {
  display: flex;
  justify-content: center;
  gap: clamp(1rem, 3vw, 3rem);
  margin: 2.5rem 0;
  position: relative;
  z-index: 1;
  flex-wrap: wrap;
}

.timeline-card {
  background: rgba(255, 255, 255, 0.15);
  padding: 1rem 2rem;
  border-radius: 16px;
  font-weight: 600;
  font-size: 0.95rem;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  border: 2px solid rgba(255, 255, 255, 0.2);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  color: white;
  text-align: center;
  min-width: 80px;
}

.timeline-card:hover {
  background: rgba(255, 255, 255, 0.25);
  transform: translateY(-2px);
  border-color: rgba(255, 255, 255, 0.4);
}

.timeline-card.past {
  background: rgba(255, 107, 107, 0.2);
  border-color: rgba(255, 107, 107, 0.3);
}

.timeline-card.present {
  background: rgba(78, 205, 196, 0.2);
  border-color: rgba(78, 205, 196, 0.3);
}

.timeline-card.future {
  background: rgba(69, 183, 209, 0.2);
  border-color: rgba(69, 183, 209, 0.3);
}

.timeline-card.past:hover {
  background: rgba(255, 107, 107, 0.3);
  border-color: rgba(255, 107, 107, 0.5);
}

.timeline-card.present:hover {
  background: rgba(78, 205, 196, 0.3);
  border-color: rgba(78, 205, 196, 0.5);
}

.timeline-card.future:hover {
  background: rgba(69, 183, 209, 0.3);
  border-color: rgba(69, 183, 209, 0.5);
}
.lesson-info {
  font-size: clamp(1rem, 2.5vw, 1.3rem);
  opacity: 0.9;
  position: relative;
  z-index: 1;
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.5;
}

/* Headings */
.slide-content h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  margin-bottom: 2rem;
  color: #1a202c;
  text-align: center;
  letter-spacing: -0.025em;
  line-height: 1.2;
}

.slide-content h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 600;
  margin-bottom: 1.5rem;
  color: #2d3748;
  letter-spacing: -0.015em;
  line-height: 1.3;
}

.slide-content h3 {
  font-size: clamp(1.25rem, 2.5vw, 1.5rem);
  font-weight: 600;
  margin-bottom: 1rem;
  color: #4a5568;
  letter-spacing: -0.01em;
  line-height: 1.4;
}

/* Objectives Grid */
.objectives-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.objective-card {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 2.5rem 2rem;
  border-radius: 20px;
  text-align: center;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
  cursor: pointer;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.objective-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.1) 0%,
    transparent 50%
  );
  opacity: 0;
  transition: opacity 0.3s ease;
}

.objective-card:hover {
  transform: translateY(-8px) scale(1.02);
  box-shadow: 0 20px 40px rgba(102, 126, 234, 0.3);
}

.objective-card:hover::before {
  opacity: 1;
}

.objective-card i {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  opacity: 0.9;
  display: block;
}

.objective-card h3 {
  color: white;
  margin-bottom: 1rem;
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.015em;
}

.objective-card p {
  line-height: 1.6;
  font-size: 1rem;
  opacity: 0.9;
}

/* Tenses Overview Table */
.tenses-overview {
  overflow-x: auto;
  margin-top: 2rem;
  border-radius: 16px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.tenses-table {
  width: 100%;
  border-collapse: collapse;
  background: white;
  border-radius: 16px;
  overflow: hidden;
  font-size: 0.95rem;
}

.tenses-table th {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 1.25rem 1rem;
  font-weight: 600;
  text-align: left;
  font-size: 0.95rem;
  letter-spacing: 0.025em;
  border: none;
}

.tenses-table td {
  padding: 1.25rem 1rem;
  border-bottom: 1px solid #e2e8f0;
  font-weight: 500;
  font-size: 0.9rem;
  line-height: 1.4;
  vertical-align: top;
}

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

.tenses-table tbody tr:hover {
  background: #f7fafc;
}

.time-label {
  background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
  font-weight: 700;
  color: #2d3748;
  position: relative;
}

.time-label::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: linear-gradient(180deg, #667eea 0%, #764ba2 100%);
}

/* Tense Explanation Layout */
.tense-explanation {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: start;
}

.formation {
  background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
  padding: 2rem;
  border-radius: 16px;
  border-left: 4px solid #667eea;
  position: relative;
  overflow: hidden;
}

.formation::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 60px;
  height: 60px;
  background: rgba(102, 126, 234, 0.1);
  border-radius: 50%;
  transform: translate(20px, -20px);
}

.formation h3 {
  color: #2d3748;
  margin-bottom: 1rem;
  font-weight: 700;
}

.formula {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 1.1rem;
  font-weight: 600;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

.subject {
  background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.025em;
  box-shadow: 0 2px 8px rgba(79, 172, 254, 0.3);
}

.auxiliary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.025em;
  box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
}

.verb {
  background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.025em;
  box-shadow: 0 2px 8px rgba(240, 147, 251, 0.3);
}

.usage-section {
  background: linear-gradient(135deg, #fff5f5 0%, #fed7d7 100%);
  padding: 2rem;
  border-radius: 16px;
  border-left: 4px solid #f56565;
  position: relative;
  overflow: hidden;
}

.usage-section::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 60px;
  height: 60px;
  background: rgba(245, 101, 101, 0.1);
  border-radius: 50%;
  transform: translate(20px, -20px);
}

.usage-section h3 {
  color: #2d3748;
  margin-bottom: 1rem;
  font-weight: 700;
}

.usage-list {
  list-style: none;
  margin-top: 1rem;
}

.usage-list li {
  margin-bottom: 1rem;
  padding-left: 2rem;
  position: relative;
  line-height: 1.6;
  color: #4a5568;
}

.usage-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: #f56565;
  font-weight: bold;
  font-size: 1.2rem;
}

.usage-list li strong {
  color: #2d3748;
}

.examples-section {
  grid-column: 1 / -1;
  background: linear-gradient(135deg, #f0fff4 0%, #c6f6d5 100%);
  padding: 2.5rem;
  border-radius: 16px;
  border-left: 4px solid #48bb78;
  margin-top: 2rem;
  position: relative;
  overflow: hidden;
}

.examples-section::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 80px;
  height: 80px;
  background: rgba(72, 187, 120, 0.1);
  border-radius: 50%;
  transform: translate(25px, -25px);
}

.examples-section h3 {
  color: #2d3748;
  margin-bottom: 1.5rem;
  font-weight: 700;
}

.examples-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.example {
  background: white;
  padding: 1.5rem;
  border-radius: 12px;
  border-left: 4px solid #48bb78;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.example:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.example.positive {
  border-left-color: #48bb78;
}

.example.negative {
  border-left-color: #f56565;
}

.example.question {
  border-left-color: #4facfe;
}

.example .label {
  font-weight: 700;
  margin-right: 1rem;
  color: #2d3748;
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.example .sentence {
  font-style: italic;
  font-size: 1rem;
  color: #4a5568;
  line-height: 1.5;
}

/* Timeline Visualization */
.timeline-container {
  position: relative;
  padding: 3rem 0;
  max-width: 1000px;
  margin: 0 auto;
}

/* New Timeline Visualization Styles */
.timeline-visualization {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem;
}

.timeline-description {
  text-align: center;
  margin-bottom: 2rem;
  color: #4a5568;
  font-size: 1.1rem;
}

.main-timeline {
  position: relative;
  background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
  border-radius: 20px;
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  min-height: 400px;
  display: flex;
  flex-direction: column;
}

.timeline-axis {
  position: absolute;
  top: 60px;
  left: 5%;
  right: 5%;
  height: 4px;
  background: linear-gradient(90deg, #ff6b6b 0%, #4ecdc4 50%, #45b7d1 100%);
  border-radius: 2px;
  z-index: 1;
}

.time-marker {
  position: absolute;
  top: 48px;
  left: 50%;
  transform: translateX(-50%);
  background: #2d3748;
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: 700;
  font-size: 0.875rem;
  z-index: 10;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  border: 2px solid white;
}

.timeline-zones-container {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 2rem;
  margin-top: 80px;
  position: relative;
  z-index: 2;
}

.timeline-zone {
  position: relative;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1rem;
}

.zone-title {
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  color: #2d3748;
  text-align: center;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.past-zone .zone-title {
  color: #e53e3e;
}

.present-zone .zone-title {
  color: #38a169;
}

.future-zone .zone-title {
  color: #3182ce;
}

.tense-items {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
}

.tense-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 1rem;
  background: white;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: 2px solid transparent;
}

.tense-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  border-color: #e2e8f0;
}

.tense-visual {
  margin-bottom: 0.75rem;
  transition: all 0.2s ease;
}

.tense-visual.point {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.tense-visual.duration {
  width: 60px;
  height: 8px;
  border-radius: 4px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.tense-visual.bridge {
  width: 60px;
  height: 8px;
  border-radius: 4px;
  position: relative;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.tense-visual.bridge::before {
  content: "";
  position: absolute;
  left: -10px;
  top: 2px;
  width: 8px;
  height: 4px;
  border-radius: 4px;
  background: inherit;
}

.tense-visual.bridge::after {
  content: "";
  position: absolute;
  right: -10px;
  top: 2px;
  width: 8px;
  height: 4px;
  border-radius: 4px;
  background: inherit;
}

/* Color coding for different time periods */
.tense-visual.past {
  background: linear-gradient(135deg, #ff6b6b 0%, #ee5a52 100%);
}

.tense-visual.present {
  background: linear-gradient(135deg, #4ecdc4 0%, #44a08d 100%);
}

.tense-visual.future {
  background: linear-gradient(135deg, #45b7d1 0%, #2980b9 100%);
}

.tense-label {
  font-weight: 600;
  font-size: 0.875rem;
  color: #2d3748;
  margin-bottom: 0.25rem;
  line-height: 1.3;
}

.tense-example {
  font-size: 0.75rem;
  color: #4a5568;
  font-style: italic;
  line-height: 1.2;
}

/* Timeline Legend */
.timeline-legend {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-top: 2rem;
  padding: 1.5rem;
  background: white;
  border-radius: 16px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.875rem;
  color: #4a5568;
  font-weight: 500;
}

.legend-visual {
  flex-shrink: 0;
}

.legend-visual.point {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #667eea;
}

.legend-visual.duration {
  width: 40px;
  height: 6px;
  border-radius: 3px;
  background: #667eea;
}

.legend-visual.bridge {
  width: 40px;
  height: 6px;
  border-radius: 3px;
  background: #667eea;
  position: relative;
}

.legend-visual.bridge::before,
.legend-visual.bridge::after {
  content: "";
  position: absolute;
  width: 6px;
  height: 3px;
  border-radius: 3px;
  background: #667eea;
  top: 50%;
  transform: translateY(-50%);
}

.legend-visual.bridge::before {
  left: -8px;
}

.legend-visual.bridge::after {
  right: -8px;
}

.timeline-line {
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, #ff6b6b 0%, #4ecdc4 50%, #45b7d1 100%);
  border-radius: 2px;
  transform: translateY(-50%);
}

.timeline-section {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: 1rem;
}

.timeline-section.past {
  position: absolute;
  left: 0;
  top: 0;
  width: 30%;
}

.timeline-section.present {
  position: absolute;
  left: 35%;
  top: 0;
  width: 30%;
}

.timeline-section.future {
  position: absolute;
  right: 0;
  top: 0;
  width: 30%;
}

.timeline-now {
  position: absolute;
  left: 50%;
  top: 45%;
  transform: translateX(-50%);
  background: #ff6b6b;
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: 700;
  z-index: 10;
}

.tense-timeline-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.5rem;
}

.timeline-point {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #667eea;
}

.timeline-bar {
  width: 60px;
  height: 8px;
  border-radius: 4px;
  background: #667eea;
}

.timeline-bridge {
  width: 60px;
  height: 8px;
  border-radius: 4px;
  background: linear-gradient(90deg, #ff6b6b 0%, #4ecdc4 100%);
}

/* Common Mistakes */
.mistakes-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
  margin-top: 2rem;
  position: relative;
  z-index: 1;
  max-width: 100%;
}

.mistake-card {
  background: white;
  border-radius: 16px;
  padding: 1.5rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06);
  border-left: 4px solid #f56565;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
  min-height: 280px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.mistake-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1),
    0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.mistake-card::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 60px;
  height: 60px;
  background: rgba(245, 101, 101, 0.1);
  border-radius: 50%;
  transform: translate(20px, -20px);
}

.mistake-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  position: relative;
  z-index: 2;
}

.mistake-header i {
  color: #f56565;
  font-size: 1.5rem;
}

.mistake-header h3 {
  color: #2d3748;
  font-weight: 600;
  margin: 0;
}

.mistake-example {
  margin-bottom: 1.5rem;
  position: relative;
  z-index: 2;
}

.wrong {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
  padding: 0.75rem;
  background: linear-gradient(135deg, #fed7d7 0%, #feb2b2 100%);
  border-radius: 8px;
  border: 1px solid rgba(245, 101, 101, 0.2);
  font-size: 0.875rem;
  line-height: 1.4;
}

.correct {
  display: flex;
  gap: 0.75rem;
  padding: 0.75rem;
  background: linear-gradient(135deg, #c6f6d5 0%, #9ae6b4 100%);
  border-radius: 8px;
  border: 1px solid rgba(72, 187, 120, 0.2);
  font-size: 0.875rem;
  line-height: 1.4;
}

.wrong .label {
  color: #c53030;
  font-weight: 700;
  min-width: 70px;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  flex-shrink: 0;
}

.correct .label {
  color: #2f855a;
  font-weight: 700;
  min-width: 70px;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  flex-shrink: 0;
}

.mistake-tip {
  background: linear-gradient(135deg, #ebf8ff 0%, #bee3f8 100%);
  padding: 0.75rem;
  border-radius: 8px;
  font-style: italic;
  color: #2a4365;
  border-left: 3px solid #3182ce;
  position: relative;
  z-index: 2;
  font-size: 0.875rem;
  line-height: 1.4;
  margin-top: auto;
}

/* Practice Section */
.practice-section {
  max-width: 900px;
  margin: 0 auto;
}

.practice-question {
  background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  padding: 3rem;
  border-radius: 24px;
  text-align: center;
  margin-bottom: 2rem;
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.practice-question h3 {
  margin-bottom: 2rem;
  color: #2d3748;
  font-weight: 700;
}

.question-text {
  font-size: clamp(1.25rem, 3vw, 1.5rem);
  margin-bottom: 2.5rem;
  font-weight: 600;
  color: #1a202c;
  background: white;
  padding: 1.5rem;
  border-radius: 16px;
  border: 2px solid #e2e8f0;
}

.options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.option-btn {
  background: white;
  border: 2px solid #e2e8f0;
  padding: 1rem 1.5rem;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-weight: 600;
  font-size: 0.95rem;
  position: relative;
  overflow: hidden;
}

.option-btn::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(102, 126, 234, 0.1),
    transparent
  );
  transition: left 0.5s ease;
}

.option-btn:hover:not(:disabled) {
  border-color: #667eea;
  background: #f7fafc;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.15);
}

.option-btn:hover:not(:disabled)::before {
  left: 100%;
}

.option-btn.correct {
  background: linear-gradient(135deg, #48bb78 0%, #38a169 100%);
  color: white;
  border-color: #38a169;
  box-shadow: 0 4px 12px rgba(72, 187, 120, 0.3);
}

.option-btn.wrong {
  background: linear-gradient(135deg, #f56565 0%, #e53e3e 100%);
  color: white;
  border-color: #e53e3e;
  box-shadow: 0 4px 12px rgba(245, 101, 101, 0.3);
}

.explanation {
  background: white;
  padding: 2rem;
  border-radius: 16px;
  border-left: 5px solid #48bb78;
  text-align: left;
  margin-top: 2rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.explanation.hidden {
  display: none;
}

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

.btn-secondary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 1rem 2rem;
  border-radius: 12px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-size: 0.95rem;
  letter-spacing: 0.025em;
}

.btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.btn-secondary:active {
  transform: translateY(-1px);
}

.score {
  font-size: 1.25rem;
  font-weight: 700;
  color: #2d3748;
  background: white;
  padding: 0.75rem 1.5rem;
  border-radius: 12px;
  border: 2px solid #e2e8f0;
}

/* Signal Words */
.signal-words-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.signal-group {
  background: #f8f9ff;
  padding: 2rem;
  border-radius: 15px;
  border-left: 5px solid #667eea;
}

.signal-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}

.signal-word {
  background: #667eea;
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
}

.signal-examples {
  margin-top: 3rem;
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.example-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
  padding: 1rem;
  background: #f8f9ff;
  border-radius: 10px;
}

.signal-highlight {
  background: #ff6b6b;
  color: white;
  padding: 0.3rem 0.8rem;
  border-radius: 15px;
  font-weight: 700;
  min-width: 80px;
  text-align: center;
}

.arrow {
  color: #667eea;
  font-weight: bold;
  font-size: 1.2rem;
}

.example-sentence {
  font-size: 1.1rem;
  font-weight: 500;
}

/* Applications Grid */
.applications-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.application-card {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  text-align: center;
  transition: transform 0.3s ease;
}

.application-card:hover {
  transform: translateY(-5px);
}

.application-card i {
  font-size: 2.5rem;
  color: #667eea;
  margin-bottom: 1rem;
}

.app-examples {
  text-align: left;
  margin-top: 1rem;
}

.app-examples p {
  margin-bottom: 1rem;
  padding: 1rem;
  background: #f8f9ff;
  border-radius: 8px;
  border-left: 4px solid #667eea;
}

/* Summary Styles */
.summary-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.summary-section {
  background: #f8f9ff;
  padding: 2rem;
  border-radius: 15px;
  border-left: 5px solid #667eea;
}

.summary-list {
  list-style: none;
  margin-top: 1rem;
}

.summary-list li {
  margin-bottom: 1rem;
  padding-left: 2rem;
  position: relative;
}

.summary-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #51cf66;
  font-weight: bold;
  font-size: 1.2rem;
}

.key-points {
  background: #fff5f5;
  padding: 2rem;
  border-radius: 15px;
  border-left: 5px solid #ff6b6b;
}

.takeaway-grid {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.takeaway-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem;
  background: white;
  border-radius: 10px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.takeaway-item i {
  color: #ff6b6b;
  font-size: 1.2rem;
}

/* Activities Grid */
.activities-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.activity-card {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  text-align: center;
  transition: transform 0.3s ease;
}

.activity-card:hover {
  transform: translateY(-5px);
}

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

.activity-header i {
  color: #667eea;
  font-size: 1.5rem;
}

.activity-btn {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 1rem 2rem;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.3s ease;
  margin-top: 1rem;
}

.activity-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
}

/* Assessment Styles */
.assessment-section {
  max-width: 800px;
  margin: 0 auto;
}

.assessment-questions {
  margin: 2rem 0;
}

.assessment-question {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  margin-bottom: 2rem;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.assessment-question p {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  color: #2a5298;
}

.assessment-options {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.assessment-options label {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem;
  background: #f8f9ff;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.3s ease;
}

.assessment-options label:hover {
  background: #e6f3ff;
}

.assessment-options input[type="radio"] {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 1rem 3rem;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1.1rem;
  transition: all 0.3s ease;
  display: block;
  margin: 0 auto;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
}

.assessment-results {
  background: #f0fff4;
  padding: 2rem;
  border-radius: 15px;
  border-left: 5px solid #51cf66;
  margin-top: 2rem;
  text-align: center;
}

.assessment-results.hidden {
  display: none;
}

/* Enhanced Assessment Styles */
.assessment-controls {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 2rem;
}

.loading-message {
  text-align: center;
  font-style: italic;
  color: #666;
  padding: 2rem;
}

.results-summary {
  text-align: center;
  margin-bottom: 2rem;
}

.score-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin: 1rem 0;
  font-size: 1.5rem;
  font-weight: bold;
}

.score-value {
  color: #667eea;
  font-size: 2rem;
}

.score-percentage {
  color: #666;
  font-weight: normal;
}

.performance-message {
  font-size: 1.1rem;
  margin: 1rem 0;
  padding: 1rem;
  border-radius: 8px;
}

.performance-message.excellent {
  background: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
}

.performance-message.good {
  background: #d1ecf1;
  color: #0c5460;
  border: 1px solid #bee5eb;
}

.performance-message.fair {
  background: #fff3cd;
  color: #856404;
  border: 1px solid #ffeaa7;
}

.performance-message.needs-improvement {
  background: #f8d7da;
  color: #721c24;
  border: 1px solid #f5c6cb;
}

.detailed-results {
  max-height: 400px;
  overflow-y: auto;
  margin-top: 2rem;
}

.result-item {
  margin-bottom: 1rem;
  padding: 1rem;
  border-radius: 8px;
  border: 2px solid transparent;
}

.result-item.correct {
  background: #d4edda;
  border-color: #28a745;
}

.result-item.incorrect {
  background: #f8d7da;
  border-color: #dc3545;
}

.result-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.question-number {
  font-weight: bold;
  color: #667eea;
}

.result-icon {
  font-size: 1.25rem;
  font-weight: bold;
}

.result-item.correct .result-icon {
  color: #28a745;
}

.result-item.incorrect .result-icon {
  color: #dc3545;
}

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

.question-text {
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: #333;
}

.answer-comparison {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
}

.your-answer {
  color: #666;
}

.correct-answer {
  color: #28a745;
  font-weight: 500;
}

.explanation {
  font-style: italic;
  color: #555;
  background: rgba(255, 255, 255, 0.7);
  padding: 0.5rem;
  border-radius: 4px;
  margin-top: 0.5rem;
}

.option-text {
  margin-left: 0.5rem;
}

/* Button visibility styles to replace inline styles */
#checkAnswers.hidden,
#retakeAssessment.hidden {
  display: none !important;
}

/* Resources Grid */
.resources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.resource-category {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.resource-category h3 {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  color: #2a5298;
}

.resource-category h3 i {
  color: #667eea;
}

.resource-category ul {
  list-style: none;
}

.resource-category li {
  padding: 0.8rem 0;
  border-bottom: 1px solid #f0f0f0;
  position: relative;
  padding-left: 1.5rem;
}

.resource-category li::before {
  content: "▶";
  position: absolute;
  left: 0;
  color: #667eea;
  font-size: 0.8rem;
}

.resource-category li:last-child {
  border-bottom: none;
}

/* Thank You Slide */
.thank-you-slide {
  text-align: center;
  background: linear-gradient(135deg, #51cf66 0%, #40c057 100%);
  color: white;
}

.thank-you-slide h1 {
  color: white;
  font-size: 4rem;
  margin-bottom: 1rem;
}

.thank-you-slide h2 {
  color: white;
  font-size: 2rem;
  opacity: 0.9;
  margin-bottom: 2rem;
}

.completion-message {
  margin-bottom: 2rem;
}

.completion-message i {
  font-size: 3rem;
  margin-bottom: 1rem;
  opacity: 0.9;
}

.next-steps {
  background: rgba(255, 255, 255, 0.1);
  padding: 2rem;
  border-radius: 15px;
  margin-bottom: 2rem;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

.next-steps h3 {
  color: white;
  margin-bottom: 1rem;
}

.next-steps ul {
  list-style: none;
  text-align: left;
}

.next-steps li {
  margin-bottom: 0.8rem;
  padding-left: 1.5rem;
  position: relative;
}

.next-steps li::before {
  content: "✓";
  position: absolute;
  left: 0;
  font-weight: bold;
}

.contact-info {
  background: rgba(255, 255, 255, 0.1);
  padding: 1.5rem;
  border-radius: 15px;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

/* Navigation Controls */
.navigation-controls {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 1.5rem;
  background: rgba(255, 255, 255, 0.98);
  padding: 1rem 2rem;
  border-radius: 50px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06), 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  z-index: 1000;
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.nav-btn {
  background: #667eea;
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 25px;
  cursor: pointer;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-size: 0.875rem;
  letter-spacing: 0.025em;
}

.nav-btn:hover:not(:disabled) {
  background: #5a67d8;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.nav-btn:active:not(:disabled) {
  transform: translateY(-1px);
}

.nav-btn:disabled {
  background: #cbd5e0;
  color: #a0aec0;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.slide-dots {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #cbd5e0;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.dot:hover {
  background: #a0aec0;
  transform: scale(1.2);
}

.dot.active {
  background: #667eea;
  transform: scale(1.3);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.2);
}

/* Keyboard Shortcuts Help */
.shortcuts-help {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: white;
  padding: 2rem;
  border-radius: 20px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
  z-index: 2000;
  display: none;
  min-width: 400px;
}

.shortcuts-help.active {
  display: block;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.9);
  }
  to {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
  }
}

.shortcuts-help h3 {
  margin-bottom: 1.5rem;
  color: #2a5298;
  text-align: center;
}

.shortcuts-list {
  display: grid;
  gap: 1rem;
}

.shortcut-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.8rem;
  background: #f8f9ff;
  border-radius: 8px;
}

.key {
  background: #667eea;
  color: white;
  padding: 0.3rem 0.8rem;
  border-radius: 6px;
  font-weight: 600;
  font-family: monospace;
  min-width: 40px;
  text-align: center;
}

.close-shortcuts {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: #999;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.close-shortcuts:hover {
  color: #667eea;
}

/* Responsive Design */
@media (max-width: 1024px) {
  .slide-content {
    padding: 2.5rem 2rem;
    min-height: 500px;
    margin: 1rem;
    max-width: calc(100% - 2rem);
  }

  .title-slide h1 {
    font-size: clamp(2rem, 6vw, 3rem);
  }

  .slide-content h1 {
    font-size: clamp(1.75rem, 5vw, 2.5rem);
  }

  .tense-explanation {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .timeline-visual {
    gap: 1.5rem;
    flex-wrap: wrap;
  }

  .summary-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .objectives-grid {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
  }

  .navigation-controls {
    padding: 0.875rem 1.5rem;
    gap: 1.25rem;
  }

  .nav-btn {
    padding: 0.625rem 1.25rem;
    font-size: 0.8rem;
  }
}

@media (max-width: 768px) {
  .slideshow-container {
    padding-top: 80px;
  }

  .slide {
    height: calc(100vh - 160px);
    padding: 0.5rem;
  }

  .slide-content {
    padding: 1.5rem 1rem;
    min-height: 300px;
    max-height: calc(100vh - 180px);
    margin: 0.5rem auto;
    width: 95%;
    border-radius: 16px;
  }

  .header-content {
    padding: 0 1rem;
    height: 56px;
  }

  .brand {
    font-size: 1.125rem;
  }

  .brand i {
    font-size: 1.25rem;
  }

  .control-btn {
    padding: 0.5rem;
    min-width: 36px;
    height: 36px;
    font-size: 0.8rem;
  }

  .navigation-controls {
    bottom: 1rem;
    padding: 0.75rem 1.25rem;
    gap: 1rem;
    flex-wrap: wrap;
    max-width: calc(100% - 2rem);
  }

  .nav-btn {
    padding: 0.5rem 1rem;
    font-size: 0.8rem;
    border-radius: 20px;
  }

  .slide-counter,
  .timer-display {
    position: relative;
    margin: 0.5rem;
    display: inline-block;
    font-size: 0.8rem;
    padding: 0.375rem 0.75rem;
  }

  .objectives-grid,
  .mistakes-grid,
  .applications-grid,
  .activities-grid,
  .resources-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

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

  .formula {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }

  .examples-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .timeline-section {
    position: static;
    width: 100%;
    margin-bottom: 2rem;
  }

  .timeline-now {
    position: static;
    transform: none;
    margin: 1rem 0;
    text-align: center;
    display: inline-block;
  }

  /* New Timeline Responsive Styles */
  .main-timeline {
    padding: 2rem 1rem;
    min-height: 300px;
  }

  .timeline-zones-container {
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 60px;
  }

  .timeline-zone {
    width: 100%;
    margin-bottom: 1rem;
    padding: 1rem 0;
  }

  .timeline-axis {
    display: none;
  }

  .time-marker {
    position: static;
    transform: none;
    margin: 1rem auto 2rem;
    display: inline-block;
  }

  .timeline-legend {
    flex-direction: column;
    gap: 1rem;
    align-items: center;
  }

  .shortcuts-help {
    min-width: 90vw;
    max-width: 400px;
    margin: 1rem;
    padding: 1.5rem;
  }

  .tenses-table th,
  .tenses-table td {
    padding: 0.875rem 0.75rem;
    font-size: 0.85rem;
  }
}

@media (max-width: 480px) {
  .slide-content {
    padding: 1.5rem 1rem;
    border-radius: 12px;
  }

  .navigation-controls {
    flex-direction: column;
    gap: 0.75rem;
    bottom: 0.5rem;
    padding: 1rem;
    border-radius: 20px;
  }

  .nav-btn {
    padding: 0.5rem 0.875rem;
    font-size: 0.75rem;
    width: 100%;
    justify-content: center;
  }

  .slide-dots {
    order: -1;
    gap: 0.375rem;
  }

  .dot {
    width: 8px;
    height: 8px;
  }

  .tenses-table {
    font-size: 0.75rem;
  }

  .tenses-table th,
  .tenses-table td {
    padding: 0.625rem 0.5rem;
  }

  .objective-card {
    padding: 2rem 1.5rem;
  }

  .timeline-visual {
    gap: 0.75rem;
  }

  .timeline-card {
    padding: 0.75rem 1rem;
    font-size: 0.85rem;
  }

  .control-btn {
    min-width: 32px;
    height: 32px;
    padding: 0.25rem;
  }
}

/* Print Styles */
@media print {
  .slideshow-header,
  .navigation-controls,
  .shortcuts-help,
  .slide-counter,
  .timer-display,
  .progress-bar {
    display: none !important;
  }

  .slide {
    display: block !important;
    height: auto;
    page-break-after: always;
    padding: 2rem;
  }

  .slide-content {
    box-shadow: none;
    border: 1px solid #ccc;
  }

  .slideshow-container {
    padding-top: 0;
  }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  .slide-content {
    border: 2px solid #000;
  }

  .objective-card,
  .activity-btn,
  .nav-btn {
    border: 2px solid #000;
  }

  .example {
    border-left-width: 6px;
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .slide {
    animation: none;
  }
}

/* Focus Styles for Accessibility */
.nav-btn:focus,
.option-btn:focus,
.activity-btn:focus,
.control-btn:focus {
  outline: 3px solid #667eea;
  outline-offset: 2px;
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
  /* These can be uncommented if dark mode is desired
    body {
        background: linear-gradient(135deg, #1a202c 0%, #2d3748 100%);
    }

    .slide-content {
        background: #2d3748;
        color: #fff;
    }

    .slide-content h1,
    .slide-content h2,
    .slide-content h3 {
        color: #e2e8f0;
    }
    */
}