/* ==========================================================================
   দারস নোট ও পিডিএফ ডাউনলোড সিস্টেম - মাস্টার সিএসএস স্টাইলশীট
   100% Modern, Clean, High-Contrast Light Theme
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Hind+Siliguri:wght@300;400;500;600;700&family=Inter:wght@400;500;600;700&display=swap');

:root {
  /* Primary Brand Colors */
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-dark: #1e3a8a;
  --primary-light: #3b82f6;
  --primary-subtle: #eff6ff;
  --primary-border: #bfdbfe;
  
  /* Accent */
  --accent-color: #0284c7;
  --accent-hover: #0369a1;
  
  /* Backgrounds (Clean Light Theme) */
  --body-bg: #f8fafc;
  --card-bg: #ffffff;
  --card-border: #e2e8f0;
  --card-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.05), 0 1px 2px -1px rgba(0, 0, 0, 0.05);
  --card-shadow-hover: 0 10px 15px -3px rgba(0, 0, 0, 0.07), 0 4px 6px -4px rgba(0, 0, 0, 0.03);
  
  /* Text Colors (100% Crisp High Contrast) */
  --text-main: #0f172a;       /* Deep Charcoal for Headings & Labels */
  --text-body: #334155;       /* Sharp Slate for Body text */
  --text-muted: #64748b;      /* Slate for Subtitles & Meta */
  --text-light: #94a3b8;      /* Placeholder text */
  --text-white: #ffffff;
  
  /* Sidebar (Clean Modern Light Design) */
  --sidebar-bg: #ffffff;
  --sidebar-border: #e2e8f0;
  --sidebar-text: #334155;
  --sidebar-text-muted: #64748b;
  --sidebar-hover-bg: #f1f5f9;
  --sidebar-active-bg: #eff6ff;
  --sidebar-active-text: #2563eb;
  
  /* Status Colors */
  --success-bg: #dcfce7;
  --success-text: #15803d;
  --success-border: #86efac;
  
  --danger-bg: #fee2e2;
  --danger-text: #b91c1c;
  --danger-border: #fca5a5;
  
  --warning-bg: #fef3c7;
  --warning-text: #b45309;
  --warning-border: #fde68a;
  
  --info-bg: #e0f2fe;
  --info-text: #0369a1;
  --info-border: #7dd3fc;

  /* Form & Borders */
  --border-color: #e2e8f0;
  --input-bg: #ffffff;
  --input-border: #cbd5e1;
  --input-focus-border: #2563eb;
  --input-focus-ring: rgba(37, 99, 235, 0.15);

  /* Fonts & Metrics */
  --font-bn: 'Hind Siliguri', sans-serif;
  --font-en: 'Inter', system-ui, sans-serif;
  --sidebar-width: 260px;
  --header-height: 64px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-pill: 50px;
  --transition-fast: 0.2s ease;
}

/* ==========================================================================
   RESET & BASE
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--body-bg);
}

body {
  font-family: var(--font-bn);
  background-color: var(--body-bg) !important;
  color: var(--text-body) !important;
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 7px;
  height: 7px;
}
::-webkit-scrollbar-track {
  background: #f1f5f9;
}
::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-bn);
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: 0.5rem;
  color: var(--text-main) !important;
}

h1 { font-size: 1.85rem; }
h2 { font-size: 1.45rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.1rem; }
h5 { font-size: 1rem; }
h6 { font-size: 0.875rem; }

p { margin-bottom: 1rem; color: var(--text-body); }
small, .small { font-size: 0.875rem; color: var(--text-muted); }
strong, b { font-weight: 600; color: var(--text-main); }
a { color: var(--primary-color); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--primary-hover); }

/* ==========================================================================
   LAYOUT UTILITIES
   ========================================================================== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.flex-center { display: flex; justify-content: center; align-items: center; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.justify-end { justify-content: flex-end; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }
.gap-4 { gap: 2rem; }

/* Grid */
.grid { display: grid; }
.grid-cols-1 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
.grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ==========================================================================
   FORM CONTROLS & INPUTS (100% LIGHT THEME & VISIBLE)
   ========================================================================== */
label {
  display: block;
  font-family: var(--font-bn);
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-main) !important;
  margin-bottom: 0.4rem;
}

input[type="text"],
input[type="password"],
input[type="number"],
input[type="date"],
input[type="email"],
input[type="file"],
select,
textarea,
.form-control {
  width: 100%;
  padding: 0.65rem 0.95rem;
  font-family: var(--font-bn);
  font-size: 0.95rem;
  color: var(--text-main) !important;
  background-color: #ffffff !important;
  border: 1.5px solid var(--input-border) !important;
  border-radius: var(--radius-md) !important;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  box-sizing: border-box;
}

input::placeholder,
textarea::placeholder {
  color: var(--text-light) !important;
}

input:focus,
select:focus,
textarea:focus,
.form-control:focus {
  border-color: var(--input-focus-border) !important;
  outline: none !important;
  box-shadow: 0 0 0 3px var(--input-focus-ring) !important;
  background-color: #ffffff !important;
}

input:disabled,
select:disabled,
textarea:disabled {
  background-color: #f1f5f9 !important;
  color: var(--text-muted) !important;
  cursor: not-allowed;
}

/* ==========================================================================
   BUTTONS
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.6rem 1.25rem;
  font-family: var(--font-bn);
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  line-height: 1.4;
}

.btn-primary {
  background: linear-gradient(135deg, #1d4ed8, #2563eb) !important;
  color: #ffffff !important;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
  border: none !important;
}
.btn-primary:hover {
  background: linear-gradient(135deg, #1e3a8a, #1d4ed8) !important;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.35);
  color: #ffffff !important;
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: #f1f5f9 !important;
  color: #334155 !important;
  border: 1px solid #cbd5e1 !important;
}
.btn-secondary:hover {
  background-color: #e2e8f0 !important;
  color: #0f172a !important;
}

.btn-success {
  background: linear-gradient(135deg, #059669, #10b981) !important;
  color: #ffffff !important;
  box-shadow: 0 2px 6px rgba(16, 185, 129, 0.25);
  border: none !important;
}
.btn-success:hover {
  background: linear-gradient(135deg, #047857, #059669) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.35);
  transform: translateY(-1px);
}

.btn-danger {
  background: linear-gradient(135deg, #dc2626, #ef4444) !important;
  color: #ffffff !important;
  box-shadow: 0 2px 6px rgba(239, 68, 68, 0.25);
  border: none !important;
}
.btn-danger:hover {
  background: linear-gradient(135deg, #b91c1c, #dc2626) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.35);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent !important;
  border: 1.5px solid var(--primary-color) !important;
  color: var(--primary-color) !important;
}
.btn-outline:hover {
  background: var(--primary-subtle) !important;
  color: var(--primary-hover) !important;
}

.btn-sm {
  padding: 0.35rem 0.75rem;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 0.85rem 1.75rem;
  font-size: 1.1rem;
  border-radius: var(--radius-md);
}

/* ==========================================================================
   CARDS & PANELS (LIGHT THEME)
   ========================================================================== */
.card, .panel {
  background-color: #ffffff !important;
  border: 1px solid var(--card-border) !important;
  border-radius: var(--radius-lg);
  box-shadow: var(--card-shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  color: var(--text-body) !important;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 1rem;
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-color);
}

.card-title {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main) !important;
}

/* ==========================================================================
   TABLES
   ========================================================================== */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: #ffffff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.03);
}

table, .table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  background-color: #ffffff !important;
}

table thead, .table thead {
  background-color: #f8fafc !important;
}

table thead th, .table thead th {
  padding: 0.85rem 1.15rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: #475569 !important;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  border-bottom: 1.5px solid var(--border-color);
  white-space: nowrap;
}

table tbody td, .table tbody td {
  padding: 0.95rem 1.15rem;
  font-size: 0.95rem;
  color: var(--text-main) !important;
  border-bottom: 1px solid #f1f5f9;
  vertical-align: middle;
}

table tbody tr:hover, .table tbody tr:hover {
  background-color: #f8fafc !important;
}

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

/* ==========================================================================
   BADGES
   ========================================================================== */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 0.25rem 0.65rem;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: var(--radius-pill);
  line-height: 1.3;
}

.badge-success { background-color: var(--success-bg); color: var(--success-text) !important; border: 1px solid var(--success-border); }
.badge-danger { background-color: var(--danger-bg); color: var(--danger-text) !important; border: 1px solid var(--danger-border); }
.badge-warning { background-color: var(--warning-bg); color: var(--warning-text) !important; border: 1px solid var(--warning-border); }
.badge-primary { background-color: var(--primary-subtle); color: var(--primary-color) !important; border: 1px solid var(--primary-border); }
.badge-secondary { background-color: #f1f5f9; color: #475569 !important; border: 1px solid #cbd5e1; }

/* ==========================================================================
   ALERTS & FLASH MESSAGES
   ========================================================================== */
.alert, .msg {
  padding: 0.85rem 1.15rem;
  border-radius: var(--radius-md);
  margin-bottom: 1.25rem;
  font-size: 0.95rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.alert-success, .msg.success, .msg-success {
  background-color: var(--success-bg) !important;
  color: var(--success-text) !important;
  border: 1px solid var(--success-border) !important;
}

.alert-danger, .alert-error, .msg.error, .msg-danger {
  background-color: var(--danger-bg) !important;
  color: var(--danger-text) !important;
  border: 1px solid var(--danger-border) !important;
}

.alert-warning, .msg-warning {
  background-color: var(--warning-bg) !important;
  color: var(--warning-text) !important;
  border: 1px solid var(--warning-border) !important;
}

.alert-info, .msg-info {
  background-color: var(--info-bg) !important;
  color: var(--info-text) !important;
  border: 1px solid var(--info-border) !important;
}

/* ==========================================================================
   LAYOUT: ADMIN (CLEAN LIGHT SIDEBAR & CONTENT)
   ========================================================================== */
.admin-layout {
  display: flex;
  min-height: 100vh;
  background-color: var(--body-bg) !important;
}

.admin-sidebar {
  width: var(--sidebar-width);
  background-color: #ffffff !important;
  border-right: 1px solid var(--sidebar-border);
  display: flex;
  flex-direction: column;
  position: fixed;
  height: 100vh;
  z-index: 100;
  transition: transform 0.3s ease;
  box-shadow: 2px 0 6px rgba(0,0,0,0.03);
}

.sidebar-header {
  height: var(--header-height);
  display: flex;
  align-items: center;
  padding: 0 1.25rem;
  border-bottom: 1px solid var(--sidebar-border);
  background-color: #ffffff;
}

.sidebar-logo {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary-dark) !important;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 10px;
}

.sidebar-nav {
  padding: 1rem 0;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  overflow-y: auto;
  flex: 1;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.7rem 1.15rem;
  color: #475569 !important;
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-fast);
  border-radius: var(--radius-md);
  margin: 0.15rem 0.85rem;
}

.sidebar-link:hover {
  background-color: #f1f5f9 !important;
  color: #0f172a !important;
}

.sidebar-link.active {
  background: #eff6ff !important;
  color: #2563eb !important;
  font-weight: 700;
  border-left: 3.5px solid #2563eb;
  box-shadow: 0 1px 3px rgba(37, 99, 235, 0.08);
}

.admin-main {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background-color: var(--body-bg) !important;
}

.admin-header {
  height: var(--header-height);
  background-color: #ffffff !important;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  position: sticky;
  top: 0;
  z-index: 90;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.admin-content {
  padding: 2rem;
  flex: 1;
  background-color: var(--body-bg) !important;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-main);
  font-size: 1.5rem;
  cursor: pointer;
}

/* ==========================================================================
   LAYOUT: STUDENT (LIGHT THEME NAVBAR & CONTENT)
   ========================================================================== */
.student-layout {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background-color: var(--body-bg) !important;
}

.student-navbar {
  height: var(--header-height);
  background-color: #ffffff !important;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 90;
  box-shadow: 0 1px 4px rgba(0,0,0,0.05);
}

.student-navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.student-main {
  flex: 1;
  padding: 2rem 0;
  background-color: var(--body-bg) !important;
}

/* ==========================================================================
   DASHBOARD STATS CARDS
   ========================================================================== */
.stat-card {
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  color: #ffffff !important;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.12);
}
.stat-card * {
  color: #ffffff !important;
}

.stat-card-primary { background: linear-gradient(135deg, #1e40af, #3b82f6); }
.stat-card-success { background: linear-gradient(135deg, #047857, #10b981); }
.stat-card-warning { background: linear-gradient(135deg, #d97706, #f59e0b); }
.stat-card-danger { background: linear-gradient(135deg, #b91c1c, #ef4444); }
.stat-card-accent { background: linear-gradient(135deg, #0369a1, #0284c7); }

.stat-value { font-size: 2.25rem; font-weight: 700; font-family: var(--font-en); margin-bottom: 0.25rem; }
.stat-title { font-size: 1rem; opacity: 0.9; }
.stat-icon { position: absolute; right: 1rem; bottom: 0.75rem; font-size: 3.5rem; opacity: 0.25; pointer-events: none; }

/* ==========================================================================
   MODALS
   ========================================================================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(15, 23, 42, 0.4);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s ease;
}

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

.modal {
  background-color: #ffffff;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  max-width: 500px;
  width: 90%;
  padding: 1.75rem;
  transform: translateY(15px);
  transition: all 0.25s ease;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
}

.modal-overlay.active .modal {
  transform: translateY(0);
}

.modal-title {
  margin-bottom: 0.75rem;
  font-size: 1.35rem;
  color: var(--text-main);
}

.modal-body {
  margin-bottom: 1.5rem;
  color: var(--text-body);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
}

/* ==========================================================================
   ANIMATIONS
   ========================================================================== */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideUp { from { opacity: 0; transform: translateY(15px); } to { opacity: 1; transform: translateY(0); } }

.animate-fade-in { animation: fadeIn 0.4s ease-out forwards; }
.animate-slide-up { animation: slideUp 0.4s ease-out forwards; }

/* ==========================================================================
   RESPONSIVE DESIGN
   ========================================================================== */
@media (max-width: 1024px) {
  .grid-cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 768px) {
  .grid-cols-3 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
  .grid-cols-2 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
  
  .admin-sidebar {
    transform: translateX(-100%);
  }
  
  .admin-sidebar.show {
    transform: translateX(0);
  }
  
  .admin-main {
    margin-left: 0;
  }
  
  .mobile-toggle {
    display: block;
  }
  
  .admin-header {
    padding: 0 1rem;
  }
  
  .admin-content {
    padding: 1.25rem;
  }
}