/* General Reset with Enhanced Variables */
:root {
  --primary-color: #2563eb;
  --primary-light: #4f86ff;
  --primary-dark: #1e40af;
  --text-light: #ffffff;
  --text-dark: #2c3e50;
  --shadow-light: rgba(0, 0, 0, 0.1);
  --shadow-medium: rgba(0, 0, 0, 0.2);
  --shadow-dark: rgba(0, 0, 0, 0.3);
  --transition-fast: 0.2s ease;
  --transition-medium: 0.3s ease;
  --transition-slow: 0.5s ease;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  overflow-x: hidden;
  max-width: 100vw;
}

body {
  font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', sans-serif;
  background: linear-gradient(135deg, #f7f9fc 0%, #eff4ff 100%);
  color: #2c3e50;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.6;
  overflow-x: hidden;
  max-width: 100vw;
}

/* Enhanced Header */
header {
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: clamp(0.8rem, 2vh, 1.2rem) clamp(1rem, 3vw, 2.5rem);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  box-shadow: 0 4px 12px var(--shadow-light);
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all var(--transition-medium);
  flex-wrap: wrap;
  gap: clamp(0.5rem, 2vw, 1rem);
  width: 100%;
}

header:hover {
  box-shadow: 0 6px 16px var(--shadow-medium);
}

header h1 {
  font-size: clamp(1.3rem, 3vw, 1.8rem);
  font-weight: 700;
  color: var(--primary-color);
  letter-spacing: -0.5px;
  text-shadow: 0 2px 4px var(--shadow-light);
  transition: all var(--transition-medium);
}

/* Back Button Styling */
.back-button {
  background: #699bf7;
  color: white;
  border: none;
  padding: clamp(0.5rem, 1.5vh, 0.8rem) clamp(0.8rem, 2vw, 1.5rem);
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: all var(--transition-medium);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.20);
  font-size: clamp(0.8rem, 1.5vw, 1rem);
  text-decoration: none;
  min-height: 44px;
  min-width: 44px;
  white-space: nowrap;
}

.back-button:hover {
  background: var(--primary-light);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.30);
}

/* Main Content */
main {
  flex: 1;
  padding: clamp(1rem, 3vh, 3rem) clamp(0.5rem, 2vw, 2rem);
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
}

.layout-container {
  width: 100%;
  max-width: 100%;
}

/* Content Header - Title on Left, Tabs on Right */
.content-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: clamp(1.5rem, 3vh, 3rem);
  gap: clamp(0.8rem, 2vw, 2rem);
  flex-wrap: wrap;
  padding: clamp(0.8rem, 2vh, 1.5rem) clamp(1rem, 2.5vw, 2rem);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border-radius: clamp(12px, 2vw, 20px);
  box-shadow: 0 4px 16px var(--shadow-light);
  width: 100%;
}

.section-title {
  font-size: clamp(1.4rem, 3.5vw, 2.8rem);
  color: #2c3e50;
  position: relative;
  margin: 0;
  font-weight: 700;
  flex-shrink: 0;
  padding-bottom: clamp(8px, 1.5vh, 12px);
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: clamp(50px, 40%, 120px);
  height: clamp(3px, 0.5vh, 4px);
  background: linear-gradient(45deg, #4f86ff, #2563eb);
  border-radius: 2px;
}

/* Band Tabs */
.band-tabs {
  display: flex;
  gap: clamp(0.4rem, 1vw, 0.75rem);
  justify-content: flex-end;
  flex-wrap: wrap;
}

.band-tab {
  border: 1px solid rgba(0, 0, 0, 0.08);
  background: #fff;
  padding: clamp(0.4rem, 1.2vh, 0.7rem) clamp(0.6rem, 1.5vw, 1.2rem);
  border-radius: 999px;
  font-weight: 600;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), background var(--transition-fast);
  box-shadow: 0 2px 6px var(--shadow-light);
  font-size: clamp(0.75rem, 1.4vw, 1rem);
  min-height: 44px;
  min-width: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
}

.band-tab:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 10px var(--shadow-medium);
}

.band-tab.is-active {
  background: linear-gradient(135deg, #699bf7, var(--primary-light));
  color: #fff;
  box-shadow: 0 6px 14px rgba(37, 99, 235, 0.30);
}

/* Content Section */
.content {
  width: 100%;
  max-width: 100%;
}

/* Grade Grid - Fully Responsive */
.grade-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, clamp(140px, 18vw, 220px)), 1fr));
  gap: clamp(1rem, 2.5vw, 2.5rem);
  margin: 0;
  width: 100%;
}

/* Enhanced Grade Card Styling - Responsive Blue Cards */
.grade-card {
  background: linear-gradient(135deg, #699bf7, var(--primary-light));
  color: var(--text-light);
  padding: clamp(1.2rem, 3vh, 3rem) clamp(1rem, 2vw, 2rem);
  border-radius: clamp(16px, 2.5vw, 24px);
  text-align: center;
  cursor: pointer;
  font-weight: 600;
  font-size: clamp(1rem, 2vw, 1.5rem);
  transition: all var(--transition-medium);
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.25);
  position: relative;
  overflow: hidden;
  border: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: clamp(120px, 20vh, 240px);
  aspect-ratio: 1;
}

.grade-card h4 {
  font-size: clamp(1.2rem, 2.5vw, 2rem);
  margin-bottom: clamp(0.3rem, 1vh, 0.5rem);
  position: relative;
  z-index: 2;
  font-weight: 700;
}

.grade-card p {
  font-size: clamp(0.8rem, 1.5vw, 1.1rem);
  opacity: 0.95;
  position: relative;
  z-index: 2;
  font-weight: 500;
}

.grade-card::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.3) 0%, transparent 70%);
  opacity: 0;
  transition: opacity var(--transition-medium);
}

.grade-card::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, 
    rgba(255, 255, 255, 0.15) 0%, 
    rgba(255, 255, 255, 0) 50%, 
    rgba(0, 0, 0, 0.05) 100%);
  border-radius: clamp(16px, 2.5vw, 24px);
}

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

.grade-card:hover {
  transform: translateY(-8px) scale(1.03);
  box-shadow: 0 15px 35px rgba(37, 99, 235, 0.35);
}

/* Keyboard focus for cards */
.grade-card {
  outline: none;
}

.grade-card:focus-visible {
  box-shadow: 0 0 0 4px rgba(79, 134, 255, 0.5);
}

/* Animations */
@keyframes pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(79, 134, 255, 0.70);
  }
  70% {
    box-shadow: 0 0 0 20px rgba(79, 134, 255, 0);
  }
  100% {
    box-shadow: 0 0 0 0 rgba(79, 134, 255, 0);
  }
}

@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-10px);
  }
}

/* Footer Enhancements */
footer {
  background: var(--primary-dark);
  color: var(--text-light);
  text-align: center;
  padding: clamp(1rem, 2.5vh, 2rem) clamp(0.5rem, 2vw, 1rem);
  margin-top: clamp(2rem, 4vh, 4rem);
  font-size: clamp(0.8rem, 1.4vw, 0.95rem);
  box-shadow: 0 -4px 12px var(--shadow-light);
  width: 100%;
}

/* Responsive Breakpoints */

/* Extra Large Screens */
@media (min-width: 1920px) {
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    max-width: 1800px;
    margin: 0 auto;
  }
}

/* Large Screens */
@media (max-width: 1400px) {
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 200px), 1fr));
  }
}

/* Medium Screens */
@media (max-width: 1200px) {
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 180px), 1fr));
  }
}

/* Tablet Landscape */
@media (max-width: 992px) {
  .content-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1.2rem;
  }
  
  .section-title {
    width: 100%;
  }
  
  .band-tabs {
    width: 100%;
    justify-content: flex-start;
  }
  
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 160px), 1fr));
  }
}

/* Tablet Portrait */
@media (max-width: 768px) {
  header {
    flex-direction: row;
    justify-content: space-between;
  }
  
  .content-header {
    padding: 0.8rem 1rem;
    align-items: center;
  }
  
  .band-tabs {
    justify-content: center;
    gap: 0.4rem;
  }
  
  .band-tab {
    flex: 1;
    min-width: 60px;
    padding: 0.5rem 0.6rem;
  }
  
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 140px), 1fr));
    gap: 1.2rem;
  }
  
  .grade-card {
    min-height: 140px;
  }
}

/* Mobile Landscape */
@media (max-width: 640px) {
  .grade-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
  }
  
  .grade-card {
    aspect-ratio: 1;
    min-height: 110px;
  }
}

/* Mobile Portrait */
@media (max-width: 480px) {
  main {
    padding: 1rem 0.5rem;
  }
  
  header {
    padding: 0.8rem 1rem;
  }
  
  .content-header {
    padding: 0.8rem;
    margin-bottom: 1.2rem;
    flex-direction: column;
    align-items: stretch;
  }
  
  .section-title {
    font-size: 1.4rem;
    text-align: center;
  }
  
  .section-title::after {
    left: 50%;
    transform: translateX(-50%);
  }
  
  .band-tabs {
    flex-direction: row;
    width: 100%;
    justify-content: center;
    gap: 0.3rem;
  }
  
  .band-tab {
    flex: 1;
    padding: 0.5rem 0.4rem;
    font-size: 0.75rem;
  }
  
  .grade-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.8rem;
  }
  
  .grade-card {
    min-height: 100px;
    padding: 1rem 0.5rem;
  }
  
  .grade-card h4 {
    font-size: 1.2rem;
  }
  
  .grade-card p {
    font-size: 0.8rem;
  }
}

/* Small Mobile */
@media (max-width: 360px) {
  .section-title {
    font-size: 1.2rem;
  }
  
  .band-tab {
    font-size: 0.7rem;
    padding: 0.4rem 0.3rem;
    min-width: 50px;
  }
  
  .grade-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.6rem;
  }
  
  .grade-card {
    min-height: 90px;
    padding: 0.8rem 0.4rem;
  }
  
  .grade-card h4 {
    font-size: 1.1rem;
  }
  
  .grade-card p {
    font-size: 0.75rem;
  }
  
  .back-button {
    padding: 0.5rem 0.6rem;
    font-size: 0.75rem;
  }
}

/* Touch-friendly enhancements */
@media (hover: none) and (pointer: coarse) {
  .grade-card,
  .back-button,
  .band-tab {
    min-height: 44px;
    min-width: 44px;
  }
  
  /* Disable hover animations on touch devices */
  .grade-card:hover {
    animation: none;
    transform: translateY(-4px);
  }
  
  .grade-card:active {
    transform: scale(0.97);
    transition: transform 0.1s ease;
  }
  
  .band-tab:hover {
    transform: none;
  }
  
  .band-tab:active {
    transform: scale(0.95);
  }
}

/* Landscape orientation adjustments */
@media (max-width: 768px) and (orientation: landscape) {
  .grade-grid {
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 120px), 1fr));
  }
  
  .grade-card {
    min-height: 100px;
    padding: 1rem 0.6rem;
  }
  
  main {
    padding: 1rem;
  }
}

@media (max-width: 480px) and (orientation: landscape) {
  .grade-grid {
    grid-template-columns: repeat(4, 1fr);
    gap: 0.8rem;
  }
  
  .grade-card {
    min-height: 90px;
  }
  
  .content-header {
    flex-direction: row;
    flex-wrap: wrap;
  }
}

/* Ensure images are responsive */
img {
  max-width: 100%;
  height: auto;
}

/* Prevent horizontal scroll */
html, body {
  overflow-x: hidden;
  max-width: 100vw;
}

/* Smooth transitions for responsive changes */
* {
  transition-property: padding, margin, font-size;
  transition-duration: 0.2s;
  transition-timing-function: ease;
}