/* 
 * Student Portal - Main Stylesheet
 * Modern ERP-style SaaS Dashboard
 * Compatible with GitHub Pages
 */

/* ========================================
   CSS VARIABLES - Design System
   ======================================== */
:root {
  /* Colors */
  --bg-page: #f5f6f8;
  --bg-card: #ffffff;
  --bg-sidebar: #1e293b;
  --bg-sidebar-hover: #334155;
  --bg-sidebar-active: #2563eb;
  
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #dbeafe;
  
  --success: #10b981;
  --success-light: #d1fae5;
  --danger: #ef4444;
  --danger-light: #fee2e2;
  --warning: #f59e0b;
  --warning-light: #fef3c7;
  --info: #3b82f6;
  --info-light: #dbeafe;
  
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --text-white: #ffffff;
  
  --border: #e5e7eb;
  --border-dark: #d1d5db;
  
  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Layout */
  --sidebar-width: 280px;
  --sidebar-collapsed: 80px;
  --header-height: 64px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
}

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

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: 0.875rem;
  line-height: 1.5;
  color: var(--text-primary);
  background-color: var(--bg-page);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-hover);
}

img {
  max-width: 100%;
  height: auto;
}

button {
  font-family: inherit;
  cursor: pointer;
}

input, select, textarea {
  font-family: inherit;
  font-size: inherit;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--text-primary);
}

h1 { font-size: 1.875rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.125rem; }
h5 { font-size: 1rem; }
h6 { font-size: 0.875rem; }

/* ========================================
   LAYOUT STRUCTURE
   ======================================== */
.app-container {
  display: flex;
  min-height: 100vh;
  width: 100%;
  max-width: 100vw;
  overflow-x: hidden;
}

/* Sidebar */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--bg-sidebar);
  color: var(--text-white);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal), width var(--transition-normal);
  overflow-y: auto;
  overflow-x: hidden;
}

.sidebar-header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.sidebar-logo {
  width: 40px;
  height: 40px;
  background: var(--primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.25rem;
}

.sidebar-title {
  font-size: 1.125rem;
  font-weight: 600;
}

.sidebar-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.sidebar-nav {
  flex: 1;
  padding: var(--spacing-md) 0;
}

.nav-section {
  margin-bottom: var(--spacing-md);
}

.nav-section-title {
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.nav-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md) var(--spacing-lg);
  color: rgba(255, 255, 255, 0.7);
  transition: background var(--transition-fast), color var(--transition-fast);
  cursor: pointer;
  border-left: 3px solid transparent;
  height: 46px;
  box-sizing: border-box;
}

.nav-item:hover {
  background: var(--bg-sidebar-hover);
  color: var(--text-white);
}

.nav-item.active {
  background: rgba(37, 99, 235, 0.2);
  color: var(--text-white);
  border-left-color: var(--primary);
}

.nav-item svg, .nav-item i {
  width: 20px;
  height: 20px;
  min-width: 20px;
  min-height: 20px;
  flex-shrink: 0;
}

.nav-item span {
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-badge {
  background: var(--danger);
  color: white;
  font-size: 0.625rem;
  padding: 2px 6px;
  border-radius: var(--radius-full);
  font-weight: 600;
  flex-shrink: 0;
  margin-left: auto;
}

/* Sidebar Footer */
.sidebar-footer {
  padding: var(--spacing-md) var(--spacing-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-user {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.sidebar-avatar {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.875rem;
}

.sidebar-user-info {
  flex: 1;
  min-width: 0;
}

.sidebar-user-name {
  font-weight: 500;
  font-size: 0.875rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-user-role {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  max-width: calc(100vw - var(--sidebar-width));
  overflow-x: hidden;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  background: var(--bg-card);
  height: var(--header-height);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-lg);
  z-index: 100;
  gap: var(--spacing-lg);
}

.header-left {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  padding: var(--spacing-sm);
  color: var(--text-primary);
  cursor: pointer;
}

.page-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.breadcrumb a {
  color: var(--text-secondary);
}

.breadcrumb a:hover {
  color: var(--primary);
}

.breadcrumb-separator {
  color: var(--text-muted);
}

.header-search {
  flex: 1;
  max-width: 400px;
  position: relative;
}

.header-search input {
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  padding-left: 40px;
  background: var(--bg-page);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  transition: all var(--transition-fast);
}

.header-search input:focus {
  outline: none;
  border-color: var(--primary);
  background: var(--bg-card);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.header-search svg {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--text-muted);
}

.header-right {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-left: auto;
}

.header-icon-btn {
  position: relative;
  background: none;
  border: none;
  padding: var(--spacing-sm);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.header-icon-btn:hover {
  background: var(--bg-page);
  color: var(--text-primary);
}

.header-icon-btn svg {
  width: 22px;
  height: 22px;
}

.notification-badge {
  position: absolute;
  top: 4px;
  right: 4px;
  width: 8px;
  height: 8px;
  background: var(--danger);
  border-radius: 50%;
  border: 2px solid var(--bg-card);
}

.header-user {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background var(--transition-fast);
}

.header-user:hover {
  background: var(--bg-page);
}

.header-avatar {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.875rem;
}

.header-user-info {
  text-align: left;
}

.header-user-name {
  font-weight: 500;
  font-size: 0.875rem;
}

.header-user-role {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* Content Area */
.content {
  flex: 1;
  padding: var(--spacing-lg);
  max-width: 100%;
  overflow-x: hidden;
}

/* ========================================
   RESPONSIVE DESIGN
   ======================================== */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }
  
  .sidebar.active {
    transform: translateX(0);
  }
  
  .main-content {
    margin-left: 0;
    max-width: 100vw;
  }
  
  .menu-toggle {
    display: flex;
  }
  
  .sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
  }
  
  .sidebar-overlay.active {
    display: block;
  }
  
  .grid-cols-2 {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .header {
    padding: 0 var(--spacing-md);
  }
  
  .header-search {
    display: none;
  }
  
  .header-user-info {
    display: none;
  }
  
  .content {
    padding: var(--spacing-md);
  }
  
  .page-title {
    font-size: 1.125rem;
  }
  
  .text-3xl {
    font-size: 1.5rem;
  }
  
  .text-2xl {
    font-size: 1.25rem;
  }
  
  .text-xl {
    font-size: 1rem;
  }
  
  .section-header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .grid-cols-2, .grid-cols-3, .grid-cols-4 {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .header-right {
    gap: var(--spacing-sm);
  }
  
  .breadcrumb {
    display: none;
  }
  
  .content {
    padding: var(--spacing-sm);
  }
  
  .btn {
    padding: 8px 12px;
    font-size: 0.75rem;
  }
  
  .btn-sm {
    padding: 4px 8px;
    font-size: 0.7rem;
  }
  
  .card-header {
    padding: var(--spacing-sm) var(--spacing-md);
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-sm);
  }
  
  .card-body {
    padding: var(--spacing-md);
  }
  
  .metric-value {
    font-size: 1.25rem;
  }
}

/* ========================================
   UTILITY CLASSES
   ======================================== */
.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }

.bg-primary { background-color: var(--primary); }
.bg-success { background-color: var(--success); }
.bg-danger { background-color: var(--danger); }
.bg-warning { background-color: var(--warning); }

.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

.text-sm { font-size: 0.75rem; }
.text-base { font-size: 0.875rem; }
.text-lg { font-size: 1rem; }
.text-xl { font-size: 1.25rem; }
.text-2xl { font-size: 1.5rem; }
.text-3xl { font-size: 1.875rem; }

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }

.p-2 { padding: var(--spacing-sm); }
.p-3 { padding: var(--spacing-md); }
.p-4 { padding: var(--spacing-lg); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-1 { gap: var(--spacing-xs); }
.gap-2 { gap: var(--spacing-sm); }
.gap-3 { gap: var(--spacing-md); }
.gap-4 { gap: var(--spacing-lg); }

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

.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }

.w-full { width: 100%; }
.h-full { height: 100%; }

.rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-full { border-radius: var(--radius-full); }

.shadow { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}