/* =========================================================
   🎨 BIẾN MÀU & CÀI ĐẶT CƠ BẢN - THEO .EDU.VN
   ========================================================= */
:root {
  --primary-color: #1e3a8a;        /* Xanh navy đậm - giống màu logo  */
  --secondary-color: #dc2626;      /* Đỏ cam - màu điểm nhấn chính */
  --accent-color: #ea580c;         /* Cam đậm - cho các yếu tố tương tác */
  --light-color: #f8fafc;          /* Nền trắng xám nhạt */
  --dark-color: #1e293b;           /* Chữ tối */
  --text-color: #374151;           /* Màu chữ chính */
  --muted-color: #6b7280;          /* Màu chữ phụ */
  --success-color: #059669;        /* Xanh lá thành công */
  --warning-color: #d97706;        /* Vàng cảnh báo */
  --info-color: #0369a1;           /* Xanh thông tin */
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --border-radius: 8px;
}

* { 
  box-sizing: border-box; 
}

body {
  font-family: 'Segoe UI', 'Inter', 'SF Pro Display', -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--text-color);
  line-height: 1.6;
  overflow-x: hidden;
  background-color: var(--light-color);
}

/* =========================================================
   🏗️ LAYOUT CHÍNH - THEO PHONG CÁCH 
   ========================================================= */
.header {
  /* 🎯 Header theo phong cách  - ngắn và sắc nét */
  background: linear-gradient(135deg, rgba(30, 58, 138, 0.9), rgba(220, 38, 38, 0.8)), 
              url('path-to-education-banner.jpg') center/cover;
  color: #fff;
  padding: 15px 0;
  position: relative;
  min-height: 35vh;
  display: flex;
  align-items: center;
  backdrop-filter: blur(1px);
  border-bottom: 3px solid var(--secondary-color);
}

.content-section { 
  padding: 70px 0;
}

.section-title {
  position: relative;
  margin-bottom: 45px;
  font-weight: 700;
  color: var(--primary-color);
  font-size: 2.3rem;
  text-align: center;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -15px; 
  left: 50%;
  transform: translateX(-50%);
  width: 60px; 
  height: 4px;
  background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
  border-radius: 2px;
}

.footer {
  background: linear-gradient(135deg, var(--primary-color), #1e1b4b);
  color: #fff;
  padding: 60px 0 25px;
  text-align: left;
  position: relative;
}

.footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
}

.footer h5 {
  color: #fff;
  margin-bottom: 22px;
  font-weight: 600;
  padding-bottom: 10px;
  position: relative;
  font-size: 1.2rem;
}

.footer h5::after {
  content: '';
  position: absolute;
  bottom: 0; 
  left: 0;
  width: 35px; 
  height: 3px;
  background: var(--secondary-color);
  border-radius: 2px;
}

.copyright {
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  margin-top: 45px;
  padding-top: 22px;
  text-align: center;
  font-size: .9rem;
  color: rgba(255, 255, 255, 0.7);
}

/* =========================================================
   🧩 COMPONENTS - CẬP NHẬT THEO 
   ========================================================= */
/* Cards - Phong cách  */
.service-card, .card-app {
  border: none;
  border-radius: var(--border-radius);
  background: #fff;
  box-shadow: var(--shadow-md);
  overflow: hidden;
  margin-bottom: 25px;
  transition: var(--transition);
  border: 1px solid rgba(0, 0, 0, 0.05);
}

.service-card { 
  height: 100%; 
  position: relative;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
  transform: scaleX(0);
  transition: transform 0.3s ease;
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-card:hover { 
  transform: translateY(-5px); 
  box-shadow: var(--shadow-lg);
}

.card-app { 
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.card-app .card-header { 
  background: #fff; 
  border-bottom: 1px solid #e5e7eb; 
  font-weight: 600; 
  padding: 16px 20px;
  color: var(--primary-color);
}

.service-icon {
  font-size: 2.8rem;
  color: var(--secondary-color);
  margin-bottom: 18px;
  display: inline-block;
  padding: 16px;
  border-radius: 12px;
  background: linear-gradient(135deg, rgba(220, 38, 38, 0.1), rgba(234, 88, 12, 0.1));
  transition: var(--transition);
}

.service-card:hover .service-icon {
  transform: scale(1.05) rotate(5deg);
  background: linear-gradient(135deg, rgba(220, 38, 38, 0.15), rgba(234, 88, 12, 0.15));
}

/* Buttons - Phong cách  */
.btn-accent, .btn-accent-outline, .login-btn {
  font-weight: 600;
  border: none;
  border-radius: var(--border-radius);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  font-size: 0.95rem;
}

.btn-accent {
  background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
  color: white;
  box-shadow: var(--shadow-sm);
  padding: 10px 24px;
}

.btn-accent:hover { 
  background: linear-gradient(135deg, var(--accent-color), var(--secondary-color));
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-accent-outline {
  border: 2px solid var(--secondary-color);
  color: var(--secondary-color);
  background: transparent;
  padding: 8px 22px;
}

.btn-accent-outline:hover {
  background: var(--secondary-color);
  color: white;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.login-btn {
  position: absolute;
  top: 20px; 
  right: 20px;
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  color: white;
  padding: 10px 22px;
  border-radius: 25px;
  z-index: 100;
  border: 1px solid rgba(255, 255, 255, 0.25);
  font-weight: 500;
}

.login-btn:hover {
  background: rgba(255, 255, 255, 0.25);
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(0,0,0,.2);
}

/* Tables - Theo phong cách  */
.table.table-compact th, .table.table-compact td {
  padding: .5rem .6rem;
  vertical-align: middle;
  font-size: 0.9rem;
}

.table.table-compact th {
  background-color: rgba(30, 58, 138, 0.05);
  color: var(--primary-color);
  font-weight: 600;
  border-bottom: 2px solid var(--primary-color);
}

/* Tabs & Navigation -  Style */
.tabs-sticky {
  position: sticky;
  top: 0;
  z-index: 1030;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  padding-top: .5rem;
  border-bottom: 1px solid #e5e7eb;
  box-shadow: var(--shadow-sm);
}

.nav-tabs.nav-scrollable, .nav-pills.nav-scrollable {
  display: flex;
  flex-wrap: nowrap;
  overflow-x: auto;
  white-space: nowrap;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  padding-bottom: 3px;
}

.nav-tabs.nav-scrollable::-webkit-scrollbar, 
.nav-pills.nav-scrollable::-webkit-scrollbar { 
  height: 4px; 
}

.nav-tabs.nav-scrollable::-webkit-scrollbar-thumb, 
.nav-pills.nav-scrollable::-webkit-scrollbar-thumb {
  background: rgba(30, 58, 138, 0.3);
  border-radius: 4px;
}

.nav-tabs .nav-link {
  transition: all .2s ease-in-out;
  border: 1px solid transparent;
  border-radius: 6px 6px 0 0;
  font-weight: 500;
  color: var(--text-color);
}

.nav-tabs .nav-link.active {
  color: var(--secondary-color);
  border-color: var(--secondary-color) var(--secondary-color) transparent;
  font-weight: 600;
  background-color: rgba(220, 38, 38, 0.05);
}

.nav-tabs .nav-link:hover:not(.active) {
  border-color: transparent transparent var(--muted-color) transparent;
  background-color: rgba(0, 0, 0, 0.02);
}

.nav-tabs.nav-compact .nav-link {
  padding: .4rem .8rem;
  font-size: .9rem;
  line-height: 1.3;
}

/* Slideshow - Cập nhật theo  */
.slideshow-container {
  position: relative;
  height: 480px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.slide {
  display: none;
  width: 100%; 
  height: 100%;
  background-size: cover;
  background-position: center;
  position: relative;
}

.slide::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 50%;
  background: linear-gradient(transparent, rgba(30, 58, 138, 0.7));
}

.slide.active { 
  display: block; 
  animation: fadeIn 1s; 
}

.slide-controls {
  position: absolute;
  bottom: 25px; 
  left: 0; 
  right: 0;
  text-align: center;
  z-index: 2;
}

.slide-dot {
  width: 12px; 
  height: 12px;
  display: inline-block;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.5);
  margin: 0 5px;
  cursor: pointer;
  transition: var(--transition);
  border: 2px solid transparent;
}

.slide-dot.active { 
  background: #fff; 
  transform: scale(1.3); 
  border-color: var(--secondary-color);
}

.slide-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: rgba(255, 255, 255, 0.9);
  color: var(--primary-color);
  border: none;
  width: 48px; 
  height: 48px;
  border-radius: 50%;
  font-size: 1.2rem;
  display: flex; 
  align-items: center; 
  justify-content: center;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
  z-index: 2;
}

.slide-nav:hover { 
  background: white; 
  transform: translateY(-50%) scale(1.1);
  box-shadow: var(--shadow-lg);
  color: var(--secondary-color);
}

.slide-prev { left: 20px; }
.slide-next { right: 20px; }

/* Footer Elements -  Style */
.footer a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  transition: var(--transition);
  display: inline-block;
}

.footer a:hover { 
  color: var(--secondary-color); 
  padding-left: 8px; 
  transform: translateX(5px);
}

.contact-info p { 
  margin-bottom: .6rem; 
  display: flex;
  align-items: center;
}

.contact-info i { 
  width: 22px; 
  margin-right: 12px; 
  color: var(--secondary-color); 
  font-size: 1.1rem;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px; 
  height: 40px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  margin-right: 10px;
  transition: var(--transition);
  color: white;
}

.social-links a:hover {
  background: var(--secondary-color);
  color: white;
  transform: translateY(-3px) scale(1.1);
  box-shadow: 0 5px 15px rgba(0,0,0,.3);
}

.map-container {
  border-radius: var(--border-radius);
  overflow: hidden;
  height: 240px;
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.footer ul { 
  list-style: none; 
  padding: 0; 
}

.footer ul li { 
  margin-bottom: .7rem; 
  position: relative;
  padding-left: 0;
}

.footer ul li a {
  display: flex;
  align-items: center;
}

.footer ul li a i { 
  color: var(--secondary-color); 
  margin-right: 10px;
  font-size: 0.9rem;
  width: 18px;
  text-align: center;
}

/* =========================================================
   🛠️ UTILITIES - CẬP NHẬT THEO 
   ========================================================= */
.back-to-top {
  position: fixed;
  bottom: 30px; 
  right: 30px;
  width: 48px; 
  height: 48px;
  background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
  color: #fff;
  border-radius: 50%;
  display: flex; 
  align-items: center; 
  justify-content: center;
  font-size: 1.2rem;
  cursor: pointer;
  transition: var(--transition);
  opacity: 0; 
  visibility: hidden;
  z-index: 999;
  box-shadow: var(--shadow-md);
  border: 2px solid white;
}

.back-to-top.show { 
  opacity: 1; 
  visibility: visible; 
}

.back-to-top:hover { 
  background: linear-gradient(135deg, var(--accent-color), var(--secondary-color)); 
  transform: translateY(-3px) scale(1.1);
  box-shadow: var(--shadow-lg);
}

.loader {
  position: fixed;
  inset: 0;
  background: var(--light-color);
  display: flex;
  align-items: center; 
  justify-content: center;
  z-index: 9999;
  transition: opacity .5s, visibility .5s;
}

.loader.hidden { 
  opacity: 0; 
  visibility: hidden; 
}

.spinner {
  width: 60px; 
  height: 60px;
  border: 5px solid #f1f5f9;
  border-top: 5px solid var(--secondary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

.kpi-chip {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  padding: .4rem .8rem;
  border-radius: 20px;
  background: linear-gradient(135deg, rgba(220, 38, 38, 0.1), rgba(234, 88, 12, 0.1));
  color: var(--secondary-color);
  font-weight: 600;
  font-size: .85rem;
  border: 1px solid rgba(220, 38, 38, 0.2);
}

.placeholder-empty {
  padding: 2.5rem 1rem;
  text-align: center;
  color: var(--muted-color);
  border: 2px dashed #e5e7eb;
  border-radius: var(--border-radius);
  background: #fafafa;
  font-size: 1rem;
}

.app-subheader {
  background: linear-gradient(90deg, rgba(30, 58, 138, 0.08), rgba(220, 38, 38, 0.08));
  border: 1px solid rgba(0,0,0,.05);
  border-radius: var(--border-radius);
  padding: .8rem 1rem;
  border-left: 4px solid var(--secondary-color);
  font-weight: 600;
  color: var(--primary-color);
}

/* Avatar & Images */
.avatar-sm {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid #e5e7eb;
  background-color: #f9fafb;
}

.avatar-default {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

/* Clickable rows */
.clickable-row {
  cursor: pointer;
  transition: background-color 0.2s ease;
  position: relative;
}

.clickable-row:hover { 
  background-color: rgba(220, 38, 38, 0.03); 
}

.clickable-row:hover::after {
  content: '›';
  position: absolute;
  right: 15px;
  color: var(--secondary-color);
  font-weight: bold;
  font-size: 1.2rem;
}

.clickable-row td { 
  user-select: none; 
}

/* Badges */
.badge {
  font-size: 0.75rem;
  white-space: nowrap;
  padding: 0.4em 0.7em;
  border-radius: 6px;
  font-weight: 600;
}

/* Tab Switcher */
.tab-switcher {
  display: none;
  width: 100%;
  background: #fff;
  border: 1px solid #e5e7eb;
  border-radius: var(--border-radius);
  padding: .6rem .8rem;
  font-weight: 600;
  color: var(--primary-color);
  box-shadow: var(--shadow-sm);
  appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
  background-repeat: no-repeat;
  background-position: right 12px center;
  background-size: 16px;
}

.tab-switcher:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.1);
  border-color: var(--secondary-color);
}

/* =========================================================
   📱 RESPONSIVE DESIGN
   ========================================================= */
@media (max-width: 992px) {
  .footer { 
    text-align: center; 
    padding: 50px 0 20px;
  }
  
  .footer h5::after { 
    left: 50%; 
    transform: translateX(-50%); 
  }
  
  .map-container { 
    margin: 0 auto; 
    height: 200px; 
    max-width: 450px;
  }
  
  .section-title {
    font-size: 2rem;
  }
}

@media (max-width: 768px) {
  .header {
    background-attachment: scroll;
    min-height: 45vh;
    text-align: center;
    padding: 12px 0;
  }
  
  .slideshow-container { 
    height: 350px;
    border-radius: 8px;
  }
  
  .content-section {
    padding: 50px 0;
  }
  
  .table-responsive { 
    font-size: 0.85rem; 
    border-radius: 6px;
  }
  
  .table td, .table th { 
    padding: 0.45rem 0.3rem; 
  }
  
  .btn-sm { 
    padding: 0.25rem 0.5rem; 
    font-size: 0.8rem; 
  }
  
  .mobile-hidden { 
    display: none !important; 
  }
  
  .clickable-row:hover { 
    background-color: inherit; 
  }
  
  .clickable-row:hover::after {
    display: none;
  }
  
  .avatar-sm { 
    width: 32px; 
    height: 32px; 
  }
  
  .service-icon {
    font-size: 2.3rem;
    padding: 14px;
  }
  
  .login-btn {
    top: 15px;
    right: 15px;
    padding: 8px 18px;
    font-size: 0.9rem;
  }
}

@media (max-width: 576px) {
  .nav-tabs.nav-responsive, 
  .nav-pills.nav-responsive { 
    display: none !important; 
  }
  
  .tab-switcher { 
    display: block !important; 
    margin-bottom: 20px;
  }
  
  .container-fluid.app-container { 
    padding-left: .75rem; 
    padding-right: .75rem; 
  }
  
  .container-box { 
    margin: 5px; 
    padding: 10px; 
    border-radius: 6px;
  }
  
  .filter-section { 
    padding: 10px; 
  }
  
  .kpi-chip { 
    font-size: 0.8rem; 
    padding: 0.3rem 0.6rem; 
  }
  
  h4 { 
    font-size: 1.1rem; 
    margin-bottom: 1rem; 
  }
  
  .form-control, .form-select { 
    font-size: 0.9rem; 
    padding: 0.4rem 0.75rem; 
  }
  
  .filter-section .row > div { 
    margin-bottom: 8px; 
  }
  
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
    font-size: 1.1rem;
  }
  
  .section-title {
    font-size: 1.7rem;
  }
}

@media (max-width: 375px) {
  .container-box { 
    padding: 8px; 
    margin: 3px; 
  }
  
  .badge { 
    font-size: 0.7rem; 
    padding: 0.3rem 0.5rem; 
  }
  
  .avatar-sm { 
    width: 28px; 
    height: 28px; 
  }
  
  .btn-sm { 
    min-width: 32px; 
    padding: 0.2rem 0.45rem;
  }
  
  .header {
    min-height: 40vh;
  }
  
  .section-title {
    font-size: 1.5rem;
    margin-bottom: 35px;
  }
  
  .footer {
    padding: 40px 0 20px;
  }
}

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

@keyframes spin { 
  to { 
    transform: rotate(360deg); 
  } 
}

@keyframes slideInUp {
  from {
    opacity: 0;
    transform: translateY(25px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Hiệu ứng cho các phần tử khi xuất hiện */
.service-card,
.card-app {
  animation: slideInUp 0.6s ease-out;
}

/* =========================================================
   📝 GHI CHÚ TÙY CHỈNH THEO .EDU.VN
   ========================================================= */

/*
🎯 MÀU SẮC .EDU.VN ĐƯỢC ÁP DỤNG:

1. MÀU CHÍNH:
   --primary-color: #1e3a8a (Xanh navy - màu chủ đạo)
   --secondary-color: #dc2626 (Đỏ - điểm nhấn mạnh)
   --accent-color: #ea580c (Cam - cho tương tác)

2. ĐẶC ĐIỂM THIẾT KẾ :
   - Header có gradient xanh navy kết hợp đỏ
   - Border bottom màu đỏ dưới header
   - Card có viền trên màu gradient đỏ-cam khi hover
   - Button gradient đỏ-cam
   - Footer gradient xanh navy đậm

3. TÙY CHỈNH THÊM CÓ THỂ THỰC HIỆN:
   - Thay ảnh banner header bằng ảnh thực tế của trung tâm
   - Điều chỉnh độ đậm nhạt của gradient nếu cần
   - Thay đổi font chữ nếu có font riêng
   - Thêm logo và các yếu tố nhận diện thương hiệu

💡 LƯU Ý:
   - Màu sắc đã được tối ưu cho độ tương phản và accessibility
   - Responsive design hoạt động tốt trên mobile
   - Có thể điều chỉnh các biến CSS để thay đổi nhanh chóng
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