/* 
  Student Task Manager - Core Design System & Stylesheet
  Theme: Modern Glassmorphic Dark / Tech Aesthetic
*/

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=JetBrains+Mono:wght@500;700&display=swap');
@import url('https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css');

:root {
  /* Color Tokens */
  --bg-dark: #0b0f19;
  --bg-card: rgba(23, 31, 48, 0.7);
  --bg-card-hover: rgba(30, 41, 64, 0.85);
  --bg-sidebar: rgba(15, 23, 42, 0.95);
  --bg-modal: #111827;

  --accent-primary: #6366f1;
  --accent-secondary: #8b5cf6;
  --accent-cyan: #06b6d4;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;

  --gradient-brand: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #06b6d4 100%);
  --gradient-card: linear-gradient(135deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.01) 100%);
  --gradient-glow: linear-gradient(135deg, rgba(99, 102, 241, 0.25) 0%, rgba(168, 85, 247, 0.15) 100%);

  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;

  --border-light: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(99, 102, 241, 0.3);

  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.5), 0 0 30px rgba(99, 102, 241, 0.15);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

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

body {
  font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  overflow-x: hidden;
  background-image: 
    radial-gradient(circle at 15% 15%, rgba(99, 102, 241, 0.12) 0%, transparent 40%),
    radial-gradient(circle at 85% 85%, rgba(6, 182, 212, 0.1) 0%, transparent 40%);
  background-attachment: fixed;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: rgba(15, 23, 42, 0.6);
}
::-webkit-scrollbar-thumb {
  background: rgba(99, 102, 241, 0.4);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-primary);
}

/* App Container Layout */
#app {
  display: flex;
  width: 100vw;
  min-height: 100vh;
}

/* Sidebar Navigation */
.sidebar {
  width: 260px;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-light);
  backdrop-filter: blur(16px);
  display: flex;
  flex-direction: column;
  padding: 24px 16px;
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 50;
  transition: transform var(--transition-smooth);
}

.brand-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 12px 24px 12px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 24px;
}

.brand-logo {
  width: 42px;
  height: 42px;
  background: var(--gradient-brand);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 1.25rem;
  box-shadow: 0 0 20px rgba(99, 102, 241, 0.4);
}

.brand-title {
  font-size: 1.15rem;
  font-weight: 800;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.02em;
}

.nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.nav-item button {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 16px;
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.nav-item button i {
  font-size: 1.1rem;
  width: 20px;
  text-align: center;
}

.nav-item button:hover {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-main);
  border-color: var(--border-light);
}

.nav-item.active button {
  background: var(--gradient-glow);
  color: #fff;
  border-color: var(--border-glow);
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.15);
}

.sidebar-footer {
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px solid var(--border-light);
}

.vercel-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 600;
}
.vercel-badge i {
  color: #fff;
}

/* Main Content Wrapper */
.main-wrapper {
  margin-left: 260px;
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  width: calc(100vw - 260px);
}

/* Top App Header */
.top-header {
  height: 72px;
  padding: 0 36px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-light);
  background: rgba(11, 15, 25, 0.7);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 40;
}

.header-title-group h1 {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.header-title-group p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: var(--gradient-brand);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.35);
  transition: all var(--transition-fast);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-main);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
}

/* Page Views Container */
.content-area {
  padding: 32px 36px;
  flex: 1;
}

.view-section {
  display: none;
  animation: fadeIn var(--transition-smooth);
}
.view-section.active {
  display: block;
}

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

/* Metrics Dashboard Cards */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 20px;
  margin-bottom: 28px;
}

.metric-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  backdrop-filter: blur(12px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

.metric-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  transform: translateY(-3px);
}

.metric-info h3 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.metric-info .metric-value {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text-main);
}

.metric-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
}

.metric-icon.indigo { background: rgba(99, 102, 241, 0.15); color: #818cf8; }
.metric-icon.emerald { background: rgba(16, 185, 129, 0.15); color: #34d399; }
.metric-icon.amber { background: rgba(245, 158, 11, 0.15); color: #fbbf24; }
.metric-icon.rose { background: rgba(244, 63, 94, 0.15); color: #fb7185; }

/* Filter & Controls Bar */
.controls-bar {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 16px 20px;
  margin-bottom: 24px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.search-box {
  flex: 1;
  min-width: 240px;
  position: relative;
}

.search-box i {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-dim);
}

.search-box input {
  width: 100%;
  padding: 10px 14px 10px 40px;
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.9rem;
  outline: none;
  transition: border var(--transition-fast);
}

.search-box input:focus {
  border-color: var(--accent-primary);
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.select-custom {
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  color: var(--text-main);
  padding: 10px 14px;
  font-size: 0.88rem;
  outline: none;
  cursor: pointer;
}

.select-custom:focus {
  border-color: var(--accent-primary);
}

/* Tasks Grid / List Layout */
.tasks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 20px;
}

.task-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 16px;
  backdrop-filter: blur(10px);
  position: relative;
  overflow: hidden;
  transition: all var(--transition-fast);
}

.task-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--accent-primary);
}

.task-card.priority-High::before { background: var(--accent-rose); }
.task-card.priority-Medium::before { background: var(--accent-amber); }
.task-card.priority-Low::before { background: var(--accent-cyan); }

.task-card.completed {
  opacity: 0.65;
  background: rgba(15, 23, 42, 0.5);
}

.task-card.completed .task-title {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-glow);
  box-shadow: var(--shadow-sm);
}

.task-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.task-title-area {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.checkbox-btn {
  width: 22px;
  height: 22px;
  border-radius: 6px;
  border: 2px solid var(--border-light);
  background: transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: transparent;
  transition: all var(--transition-fast);
  margin-top: 2px;
}

.checkbox-btn:hover {
  border-color: var(--accent-emerald);
}

.task-card.completed .checkbox-btn {
  background: var(--accent-emerald);
  border-color: var(--accent-emerald);
  color: #fff;
}

.task-title {
  font-size: 1.05rem;
  font-weight: 700;
  line-height: 1.35;
  color: var(--text-main);
}

.task-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 4px;
}

.tag-pill {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-light);
  color: var(--text-muted);
}

.tag-pill.category {
  background: rgba(99, 102, 241, 0.12);
  color: #a5b4fc;
  border-color: rgba(99, 102, 241, 0.2);
}

.tag-pill.priority-High { background: rgba(244, 63, 94, 0.15); color: #fda4af; border-color: rgba(244, 63, 94, 0.3); }
.tag-pill.priority-Medium { background: rgba(245, 158, 11, 0.15); color: #fde68a; border-color: rgba(245, 158, 11, 0.3); }
.tag-pill.priority-Low { background: rgba(6, 182, 212, 0.15); color: #a5f3fc; border-color: rgba(6, 182, 212, 0.3); }

.task-notes {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.5;
  background: rgba(15, 23, 42, 0.4);
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border-left: 2px solid rgba(255, 255, 255, 0.1);
}

.task-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 12px;
  border-top: 1px solid var(--border-light);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.task-meta {
  display: flex;
  align-items: center;
  gap: 12px;
}

.due-indicator.overdue {
  color: var(--accent-rose);
  font-weight: 700;
}
.due-indicator.today {
  color: var(--accent-amber);
  font-weight: 700;
}

.task-actions {
  display: flex;
  align-items: center;
  gap: 6px;
}

.btn-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  background: transparent;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-main);
  border-color: var(--border-light);
}

.btn-icon.timer-btn:hover {
  color: var(--accent-primary);
  background: rgba(99, 102, 241, 0.15);
}

.btn-icon.delete-btn:hover {
  color: var(--accent-rose);
  background: rgba(244, 63, 94, 0.15);
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  background: var(--bg-card);
  border: 1px dashed var(--border-light);
  border-radius: var(--radius-lg);
  grid-column: 1 / -1;
}

.empty-state i {
  font-size: 3rem;
  color: var(--accent-primary);
  margin-bottom: 16px;
  opacity: 0.8;
}

.empty-state h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.empty-state p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 20px;
}

/* Pomodoro View Styling */
.pomodoro-container {
  max-width: 720px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 40px;
  text-align: center;
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow-lg);
}

.pomo-modes {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 36px;
}

.pomo-mode-btn {
  padding: 10px 20px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.pomo-mode-btn.active {
  background: var(--gradient-brand);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.timer-ring-wrapper {
  position: relative;
  width: 280px;
  height: 280px;
  margin: 0 auto 36px auto;
  display: flex;
  align-items: center;
  justify-content: center;
}

.timer-svg {
  transform: rotate(-90deg);
  width: 100%;
  height: 100%;
}

.timer-bg-circle {
  fill: none;
  stroke: rgba(255, 255, 255, 0.05);
  stroke-width: 10;
}

.timer-progress-circle {
  fill: none;
  stroke: url(#pomoGradient);
  stroke-width: 10;
  stroke-dasharray: 816;
  stroke-dashoffset: 0;
  stroke-linecap: round;
  transition: stroke-dashoffset 1s linear;
}

.timer-display {
  position: absolute;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.timer-time {
  font-family: 'JetBrains Mono', monospace;
  font-size: 4rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.timer-label {
  font-size: 0.9rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 700;
  margin-top: 4px;
}

.pomo-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 32px;
}

.btn-timer-main {
  padding: 14px 40px;
  font-size: 1.1rem;
  border-radius: var(--radius-full);
}

.ambient-sounds {
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 16px;
  display: flex;
  align-items: center;
  justify-content: space-around;
  gap: 12px;
}

.sound-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,0.03);
  transition: all var(--transition-fast);
}

.sound-toggle.active {
  background: rgba(99, 102, 241, 0.2);
  color: var(--accent-primary);
  border: 1px solid var(--border-glow);
}

/* Analytics View Styling */
.analytics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 24px;
}

.chart-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  backdrop-filter: blur(12px);
}

.chart-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.chart-header h3 {
  font-size: 1.1rem;
  font-weight: 700;
}

.bar-chart-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.chart-bar-item {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.bar-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  font-weight: 600;
}

.bar-track {
  height: 10px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.bar-fill {
  height: 100%;
  border-radius: var(--radius-full);
  background: var(--accent-primary);
  transition: width 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Modal Overlay */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-fast);
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-container {
  background: var(--bg-modal);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 520px;
  box-shadow: var(--shadow-lg);
  transform: scale(0.95);
  transition: transform var(--transition-fast);
  overflow: hidden;
}

.modal-overlay.active .modal-container {
  transform: scale(1);
}

.modal-header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-header h2 {
  font-size: 1.2rem;
  font-weight: 700;
}

.modal-body {
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-group label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
}

.form-control {
  width: 100%;
  padding: 11px 14px;
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.9rem;
  outline: none;
  font-family: inherit;
  transition: border var(--transition-fast);
}

.form-control:focus {
  border-color: var(--accent-primary);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.modal-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  background: rgba(15, 23, 42, 0.4);
}

/* Toast Notification */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 120;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  color: var(--text-main);
  padding: 14px 20px;
  border-radius: var(--radius-md);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.9rem;
  font-weight: 600;
  animation: slideInRight 0.3s ease-out;
}

@keyframes slideInRight {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* Responsive Rules */
@media (max-width: 900px) {
  .sidebar {
    transform: translateX(-100%);
  }
  .sidebar.mobile-open {
    transform: translateX(0);
  }
  .main-wrapper {
    margin-left: 0;
    width: 100vw;
  }
  .top-header {
    padding: 0 20px;
  }
  .content-area {
    padding: 20px;
  }
}