:root {
  /* Modern gradient colors */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-success: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --gradient-dark: linear-gradient(135deg, #2d3561 0%, #1f2347 100%);
  --gradient-card: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, rgba(255, 255, 255, 0.05) 100%);

  /* Telegram theme colors with fallbacks */
  --primary-color: var(--tg-theme-button-color, #667eea);
  --bg-color: var(--tg-theme-bg-color, #1a1d2e);
  --secondary-bg: var(--tg-theme-secondary-bg-color, #252936);
  --text-color: var(--tg-theme-text-color, #ffffff);
  --hint-color: var(--tg-theme-hint-color, #8b92b0);
  --border-color: rgba(255, 255, 255, 0.1);

  /* Glass effect */
  --glass-bg: rgba(255, 255, 255, 0.08);
  --glass-border: rgba(255, 255, 255, 0.15);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg-color);
  background-image: var(--gradient-dark);
  color: var(--text-color);
  overflow-x: hidden;
  min-height: 100vh;
}

/* Animated gradient background */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background:
    radial-gradient(circle at 20% 50%, rgba(102, 126, 234, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 80% 80%, rgba(118, 75, 162, 0.1) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

#app {
  min-height: 100vh;
  padding-bottom: 70px;
  position: relative;
  z-index: 1;
}

#content {
  padding: 16px 16px 80px;
}

/* Header */
.header {
  padding: 24px 20px;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  margin: 16px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  position: relative;
  overflow: hidden;
}

.header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
  border-radius: 24px 24px 0 0;
}

.header h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 12px;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.5px;
}

.week-indicator {
  display: inline-block;
  background: var(--gradient-success);
  color: white;
  padding: 8px 18px;
  border-radius: 24px;
  font-size: 14px;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(79, 172, 254, 0.3);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

.week-selector {
  font-size: 14px;
  color: var(--hint-color);
  margin-top: 8px;
}

/* Modern week toggle button */
.week-toggle-btn {
  padding: 10px 24px;
  border-radius: 24px;
  border: none;
  background: var(--gradient-success);
  color: white;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(79, 172, 254, 0.3);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.week-toggle-btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.3);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.week-toggle-btn:active::before {
  width: 300px;
  height: 300px;
}

.week-toggle-btn:hover {
  box-shadow: 0 4px 16px rgba(79, 172, 254, 0.5);
  transform: translateY(-2px) scale(1.02);
}

.week-toggle-btn:active {
  transform: translateY(0) scale(0.98);
}

/* Day Selector */
.day-selector {
  display: flex;
  gap: 10px;
  padding: 16px;
  padding-bottom: 20px;
  overflow-x: auto;
  overflow-y: visible;
  margin: 0 -4px;
}

.day-btn {
  flex-shrink: 0;
  padding: 10px 20px;
  border: none;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  color: var(--text-color);
  border-radius: 24px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  font-weight: 600;
  font-size: 14px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.day-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  border-color: rgba(79, 172, 254, 0.3);
}

.day-btn.active {
  background: var(--gradient-success);
  color: white;
  border: none;
  box-shadow: 0 4px 12px rgba(79, 172, 254, 0.4);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
  transform: scale(1.05);
}

/* Schedule List */
.schedule-list {
  padding: 16px;
}

.schedule-item {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  padding: 18px 20px;
  margin-bottom: 14px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

.schedule-item:hover {
  transform: translateY(-3px) scale(1.01);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15), 0 0 20px rgba(102, 126, 234, 0.2);
  border-color: rgba(102, 126, 234, 0.4);
}

.schedule-item:active {
  transform: translateY(0) scale(1);
}

.schedule-time {
  font-size: 13px;
  color: var(--hint-color);
  margin-bottom: 6px;
  font-weight: 500;
  opacity: 0.8;
}

.schedule-subject {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-color);
  line-height: 1.4;
}

.homework-badge {
  display: inline-block;
  background: var(--gradient-secondary);
  color: white;
  padding: 6px 14px;
  border-radius: 16px;
  font-size: 13px;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(240, 147, 251, 0.3);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

.schedule-item.no-subject {
  opacity: 0.5;
  cursor: default;
}

.schedule-item.no-subject:hover {
  transform: none;
  box-shadow: none;
}

/* Homework List */
.homework-list {
  padding: var(--spacing);
}

.homework-card {
  background: var(--tg-theme-secondary-bg-color);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 12px;
}

.homework-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 8px;
}

.homework-subject {
  font-weight: 600;
  font-size: 16px;
}

.homework-date {
  font-size: 12px;
  color: var(--tg-theme-hint-color);
}

.homework-content {
  font-size: 14px;
  line-height: 1.5;
  margin-bottom: 8px;
  white-space: pre-wrap;
}

.homework-files {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 8px;
}

.file-thumb {
  width: 60px;
  height: 60px;
  border-radius: 8px;
  object-fit: cover;
  cursor: pointer;
}

.file-link {
  display: inline-block;
  padding: 6px 12px;
  background: var(--primary-color);
  color: white;
  border-radius: 8px;
  text-decoration: none;
  font-size: 12px;
}

.homework-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 8px;
  font-size: 12px;
  color: var(--tg-theme-hint-color);
}

.delete-btn {
  background: #ef4444;
  color: white;
  border: none;
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
}

/* Admin Controls */
.admin-controls {
  padding: var(--spacing);
}

.admin-section {
  background: var(--tg-theme-secondary-bg-color);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 16px;
}

.admin-section h3 {
  font-size: 16px;
  margin-bottom: 12px;
}

.admin-section input {
  width: 100%;
  padding: 10px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin-bottom: 8px;
  background: var(--tg-theme-bg-color);
  color: var(--tg-theme-text-color);
}

.current-week-info {
  margin-top: 12px;
  font-size: 14px;
}

/* Bottom Navigation */
#bottom-nav {
  display: flex;
  justify-content: space-around;
  align-items: center;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 1px solid var(--glass-border);
  padding: 12px 8px;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.15);
  z-index: 100;
}

.nav-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 10px 16px;
  background: transparent;
  border: none;
  color: var(--hint-color);
  font-size: 11px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 16px;
  font-weight: 500;
}

.nav-btn.active {
  color: #667eea;
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.15), rgba(118, 75, 162, 0.1));
  box-shadow: 0 2px 8px rgba(102, 126, 234, 0.2);
  transform: scale(1.05);
}

.nav-btn:hover:not(.active) {
  background: rgba(255, 255, 255, 0.05);
  transform: scale(1.02);
}

.nav-btn-icon {
  font-size: 24px;
}

.nav-label {
  font-size: 11px;
}

/* Tabs */
.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* Buttons */
.btn-primary {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  width: 100%;
  transition: opacity 0.2s;
}

.btn-primary:hover {
  opacity: 0.9;
}

/* ========== MODAL - Modern Design ========== */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  padding: 20px;
}

.modal.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--secondary-bg);
  background-image: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.02) 100%);
  border: 1px solid var(--glass-border);
  border-radius: 28px;
  max-width: 500px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
  transform: scale(0.9) translateY(20px);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.modal.active .modal-content {
  transform: scale(1) translateY(0);
}

.modal-header {
  padding: 24px 24px 20px;
  border-bottom: 1px solid var(--border-color);
  position: relative;
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, transparent 100%);
  border-radius: 28px 28px 0 0;
}

.modal-header h2 {
  font-size: 24px;
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin: 0;
  padding-right: 40px;
}

.modal-close {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid var(--glass-border);
  color: var(--text-color);
  font-size: 24px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
}

.modal-close:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: rotate(90deg) scale(1.1);
}

.modal-body {
  padding: 24px;
}

#homework-items {
  max-height: 300px;
  overflow-y: auto;
  margin-bottom: 20px;
  padding-right: 8px;
}

/* Modern textarea */
#homework-text {
  width: 100%;
  min-height: 120px;
  padding: 16px;
  border-radius: 16px;
  border: 1px solid var(--glass-border);
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: var(--text-color);
  font-size: 15px;
  font-family: inherit;
  resize: vertical;
  transition: all 0.3s ease;
  margin-bottom: 16px;
}

#homework-text:focus {
  outline: none;
  border-color: rgba(102, 126, 234, 0.5);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1), 0 4px 12px rgba(0, 0, 0, 0.1);
  background: rgba(255, 255, 255, 0.12);
}

#homework-text::placeholder {
  color: var(--hint-color);
  opacity: 0.6;
}

/* Modern file upload */
#file-input {
  display: none;
}

.file-upload-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: 100%;
  padding: 14px;
  border-radius: 16px;
  border: 2px dashed var(--glass-border);
  background: var(--glass-bg);
  color: var(--text-color);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.3s ease;
  margin-bottom: 16px;
}

.file-upload-btn:hover {
  border-color: rgba(102, 126, 234, 0.5);
  background: rgba(102, 126, 234, 0.1);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* Modern submit button */
#submit-homework-btn {
  width: 100%;
  padding: 16px;
  border-radius: 16px;
  border: none;
  background: var(--gradient-primary);
  color: white;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(102, 126, 234, 0.3);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  margin-top: 8px;
}

#submit-homework-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(102, 126, 234, 0.4), 0 0 30px rgba(102, 126, 234, 0.2);
}

#submit-homework-btn:active {
  transform: translateY(0);
}

#file-preview {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.file-preview-item {
  position: relative;
  width: 60px;
  height: 60px;
}

.file-preview-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 8px;
}

.file-preview-item .file-name {
  font-size: 10px;
  text-align: center;
  margin-top: 4px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 40px 20px;
  color: var(--tg-theme-hint-color);
}

.empty-state-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.empty-state-text {
  font-size: 14px;
}

/* Loading */
.loading {
  text-align: center;
  padding: 20px;
  color: var(--tg-theme-hint-color);
}

/* ========== ANIMATIONS - Optimized for Telegram WebApp ========== */

/* Simple fade in - works everywhere */
@keyframes simpleFadeIn {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

/* Simple slide up - lightweight */
@keyframes simpleSlideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Simple fade out */
@keyframes simpleFadeOut {
  to {
    opacity: 0;
  }
}

/* Homework card animations - SIMPLIFIED */
.homework-card {
  /* Enable GPU acceleration */
  will-change: opacity, transform;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

/* New item - simple and fast */
.homework-card.new-item {
  animation: simpleSlideUp 0.4s ease-out forwards;
}

/* Removing item */
.homework-card.removing {
  animation: simpleFadeOut 0.25s ease-out forwards;
}

/* Highlight effect - no animation, just transition */
.homework-card.adding {
  background: var(--tg-theme-button-color);
  opacity: 0.95;
  transition: background 0.3s ease, opacity 0.3s ease;
}

/* Reset after highlight */
.homework-card {
  transition: background 0.3s ease, opacity 0.3s ease, transform 0.3s ease;
}

/* ========== IMAGE VIEWER MODAL ========== */
.image-viewer-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.95);
  z-index: 10000;
  justify-content: center;
  align-items: center;
  animation: fadeIn 0.2s ease-out;
}

.image-viewer-modal.active {
  display: flex;
}

.image-viewer-content {
  position: relative;
  max-width: 95%;
  max-height: 95%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.image-viewer-content img {
  max-width: 100%;
  max-height: 85vh;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: 0 10px 50px rgba(0, 0, 0, 0.5);
  cursor: zoom-out;
}

.image-viewer-controls {
  display: flex;
  gap: 12px;
  margin-top: 16px;
  flex-wrap: wrap;
  justify-content: center;
}

.image-viewer-btn {
  padding: 12px 24px;
  background: var(--tg-theme-button-color, #3390ec);
  color: var(--tg-theme-button-text-color, #ffffff);
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}

.image-viewer-btn:hover {
  opacity: 0.9;
  transform: translateY(-2px);
}

.image-viewer-close {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 44px;
  height: 44px;
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  border: none;
  border-radius: 50%;
  color: white;
  font-size: 24px;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-viewer-close:hover {
  background: rgba(255, 255, 255, 0.25);
  transform: scale(1.1);
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

/* File thumbnail improvements */
.file-thumb {
  width: 80px;
  height: 80px;
  border-radius: 8px;
  object-fit: cover;
  cursor: pointer;
  transition: all 0.2s;
  border: 2px solid transparent;
}

.file-thumb:hover {
  transform: scale(1.05);
  border-color: var(--primary-color);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* Download button for files */
.file-link {
  transition: all 0.2s;
}

.file-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}