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

body {
  font-family: "Arial", Helvetica, sans-serif;
  background: #fafafa;
  color: #333;
  line-height: 1.6;
}

a { text-decoration: none; color: inherit; }
button { border: none; background: none; cursor: pointer; }

/* ====================== HEADER ====================== */
header {
  background: linear-gradient(90deg, #d60ca4, #cd099c);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.header-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 20px;
  height: 70px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo a {
  font-size: 2.4rem;
  font-weight: 900;
  color: #fff;
  letter-spacing: 1px;
}

.nav {
  display: flex;
  gap: 12px;
}

.nav a {
  width: 140px;
  height: 48px;
  background: rgba(255,255,255,0.15);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255,255,255,0.3);
  border-radius: 12px;
  color: #fff;
  font-weight: 700;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
}

.nav a:hover {
  background: rgba(255,255,255,0.3);
  transform: translateY(-3px);
}

.nav a.active {
  background: rgba(255,255,255,0.4);
  font-weight: 900;
}

.mobile-menu {
  display: none;
  font-size: 2rem;
  color: #fff;
}

.nav-course-btn {
  position: relative;
  background: linear-gradient(135deg, #ff1493, #ff69b4) !important;
  color: #fff !important;
  font-weight: 900;
  box-shadow: 0 4px 15px rgba(255,20,147,0.4);
  overflow: hidden;
  transition: all 0.3s ease;
}

.nav-course-btn:hover {
  transform: translateY(-4px) scale(1.05) !important;
  box-shadow: 0 10px 25px rgba(255,20,147,0.6);
}

.new-badge {
  position: absolute;
  top: -6px;
  right: -6px;
  background: #ff0040;
  color: #fff;
  font-size: 0.65rem;
  font-weight: 900;
  padding: 4px 8px;
  border-radius: 20px;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.15); }
}

/* ====================== MOBILE MENU ====================== */
@media (max-width: 768px) {
  .mobile-menu { display: block; }
  .nav {
    position: fixed;
    top: 70px;
    inset-inline: 0;
    background: linear-gradient(90deg, #d60ca4, #cd099c);
    flex-direction: column;
    padding: 20px;
    gap: 15px;
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all 0.4s ease;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    height: calc(100vh - 70px);
    overflow-y: auto;
  }
  .nav.nav-active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  .nav a { width: 100%; height: 60px; font-size: 1.2rem; }
}

/* ====================== FOOTER ====================== */
.footer {
  background: #222;
  color: #ddd;
  text-align: center;
  padding: 20px;
  font-size: 1.1rem;
  font-weight: bold;
}

/* ====================== DOCUMENTS PAGE ====================== */
.documents-page {
  max-width: 900px;
  margin: 60px auto 40px;
  padding: 0 20px;
}

.documents-page .page-title {
  text-align: center;
  color: #be185d;
  font-size: 2.3rem;
  margin-bottom: 40px;
  font-weight: 700;
}

/* Card tài liệu */
.doc-card {
  background: #fff;
  border-radius: 16px;
  padding: 24px;
  margin-bottom: 22px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
  transition: all 0.3s ease;
  gap: 20px;
}

.doc-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 30px rgba(0,0,0,0.15);
}

.doc-info {
  flex: 1;
}

.doc-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: #333;
  margin-bottom: 6px;
}

.doc-desc {
  color: #555;
  margin-bottom: 8px;
  font-size: 1rem;
}

.doc-size {
  color: #888;
  font-size: 0.9rem;
}

.download-btn {
  background: #f472b6;
  color: #fff;
  padding: 14px 28px;
  border-radius: 12px;
  font-weight: 700;
  white-space: nowrap;
  transition: all 0.3s ease;
  box-shadow: 0 4px 10px rgba(244, 114, 182, 0.3);
}

.download-btn:hover {
  background: #ec4899;
  transform: scale(1.05);
  box-shadow: 0 8px 20px rgba(236, 72, 153, 0.4);
}

/* ====================== SEARCH HIGHLIGHT ====================== */
@keyframes cardBlink {
  0%, 100% { box-shadow: 0 4px 15px rgba(0,0,0,0.08); }
  50% { box-shadow: 0 0 30px #ff1493; transform: scale(1.02); }
}
.card-highlight {
  animation: cardBlink 0.8s ease 4;
  border-radius: 16px;
}

/* ====================== MOBILE RESPONSIVE ====================== */
@media (max-width: 768px) {
  .doc-card {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }
  .download-btn {
    align-self: flex-end;
  }
}