/* ============================================
   WEBSITE UI UPGRADE — css/style.css
   Bảng màu: Deep Navy + Gold Accent
   lophoctuni.edu.vn
   ============================================ */

/* 1. GOOGLE FONTS */
@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:wght@600;700&family=Inter:wght@400;500;600;700&display=swap');

/* 2. DESIGN TOKENS */
:root {
  /* Colors */
  --color-navy:        #1a237e;
  --color-navy-dark:   #0d1547;
  --color-navy-light:  #3949ab;
  --color-navy-mid:    #283593;
  --color-accent:      #f9a825;
  --color-accent-dark: #f57f17;
  --color-bg:          #fafafa;
  --color-surface:     #ffffff;
  --color-text-dark:   #1c1c2e;
  --color-text-muted:  #6b7280;
  --color-border:      #e5e7eb;

  /* Typography */
  --font-heading: 'Playfair Display', Georgia, serif;
  --font-body:    'Inter', sans-serif;
  --fs-h1:   2.5rem;
  --fs-h2:   1.8rem;
  --fs-h3:   1.3rem;
  --fs-body: 1rem;
  --fs-sm:   0.9rem;
  --lh-body: 1.6;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;

  /* Borders */
  --radius-sm:     8px;
  --radius-md:     12px;
  --radius-lg:     16px;
  --radius-pill:   50px;
  --radius-circle: 50%;

  /* Shadows */
  --shadow-sm:   0 2px 8px rgba(0,0,0,0.06);
  --shadow-md:   0 4px 20px rgba(0,0,0,0.08);
  --shadow-lg:   0 8px 30px rgba(0,0,0,0.15);
  --shadow-xl:   0 20px 60px rgba(0,0,0,0.3);
  --shadow-navy: 0 12px 32px rgba(26,35,126,0.15);

  /* Transitions */
  --transition-fast:   0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow:   0.5s ease;
}

/* 3. GLOBAL RESET & BASE */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  background-color: var(--color-bg);
  color: var(--color-text-dark);
  overflow-x: hidden;
}

h1, h2, h3 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.3;
}

p { line-height: var(--lh-body); }

/* 4. LAYOUT */
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: var(--space-lg) var(--space-sm);
}

.section {
  background-color: var(--color-surface);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  max-width: 800px;
  margin: 0 auto var(--space-lg) auto;
}

.section h2 {
  font-size: var(--fs-h2);
  color: var(--color-navy);
  margin-bottom: var(--space-sm);
  padding-bottom: var(--space-xs);
  border-bottom: 2px solid var(--color-accent);
  display: inline-block;
}

/* 5. ANNOUNCEMENT BAR */
.announcement-marquee {
  width: 100%;
  overflow: hidden;
  background-color: var(--color-accent);
  color: var(--color-text-dark);
  font-size: var(--fs-body);
  font-weight: 600;
  padding: 0.6rem 0;
  text-align: center;
  white-space: nowrap;
}

.announcement-marquee a {
  color: var(--color-text-dark);
  text-decoration: none;
}

.announcement-marquee span {
  display: inline-block;
  animation: marquee 20s linear infinite;
}

.announcement-marquee:hover span {
  animation-play-state: paused;
}

/* 6. HEADER */
header {
  background: linear-gradient(135deg, var(--color-navy-dark) 0%, var(--color-navy-mid) 55%, var(--color-navy-light) 100%);
  color: var(--color-surface);
  text-align: center;
  padding: var(--space-xl) var(--space-sm);
  min-height: 120px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: var(--space-xs);
}

header h1 {
  font-family: var(--font-heading);
  font-size: var(--fs-h1);
  font-weight: 700;
  letter-spacing: 3px;
  text-shadow: 0 2px 8px rgba(0,0,0,0.3);
  color: var(--color-surface);
}

header p {
  font-size: 1.05rem;
  opacity: 0.85;
  font-weight: 400;
  letter-spacing: 0.5px;
}

/* 7. NAVIGATION */
nav {
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: var(--color-navy-dark);
  height: 56px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 12px rgba(0,0,0,0.25);
}

nav a {
  color: var(--color-surface);
  text-decoration: none;
  padding: 0 var(--space-sm);
  display: flex;
  align-items: center;
  height: 100%;
  font-size: 0.95rem;
  font-weight: 500;
  transition: background-color var(--transition-fast);
  position: relative;
}

nav a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  transition: width var(--transition-fast);
}

nav a:hover {
  background-color: rgba(255,255,255,0.08);
}

nav a:hover::after {
  width: 70%;
}

.dropdown {
  position: relative;
  display: flex;
  align-items: center;
  height: 100%;
}

.dropdown > a::after {
  display: none;
}

.dropdown-content {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: var(--color-navy-dark);
  min-width: 200px;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  box-shadow: 0 8px 24px rgba(0,0,0,0.3);
  border-top: 2px solid var(--color-accent);
  z-index: 200;
}

.dropdown-content a {
  display: block;
  padding: 0.75rem var(--space-sm);
  height: auto;
  font-size: var(--fs-sm);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.dropdown-content a:last-child {
  border-bottom: none;
}

.dropdown-content a:hover {
  background-color: rgba(249,168,37,0.12);
  color: var(--color-accent);
}

.dropdown:hover .dropdown-content {
  display: block;
}

/* 8. COURSE CARDS */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-sm);
}

.course-box {
  background-color: var(--color-surface);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.course-box:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-navy);
}

.course-box h3 {
  color: var(--color-navy);
  font-size: var(--fs-h3);
  margin-bottom: var(--space-xs);
}

.course-box p {
  color: var(--color-text-muted);
  font-size: var(--fs-sm);
  line-height: var(--lh-body);
}

/* 9. SCHEDULE CARDS */
.schedule-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-md);
}

.schedule-box {
  background-color: var(--color-surface);
  border-top: 3px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  box-shadow: var(--shadow-md);
  text-align: center;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  cursor: pointer;
}

.schedule-box:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-navy);
}

.schedule-box h3 {
  color: var(--color-navy);
  font-size: var(--fs-h3);
  margin-bottom: var(--space-xs);
}

.schedule-box p {
  color: var(--color-text-muted);
  font-size: var(--fs-sm);
  margin: 4px 0;
}

/* Badges */
.badge {
  display: inline-block;
  padding: 3px 12px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-bottom: var(--space-xs);
  font-family: var(--font-body);
}

.badge-toan  { background: #e8eaf6; color: var(--color-navy); }
.badge-anh   { background: #e3f2fd; color: #0d47a1; }
.badge-ielts { background: #e8f5e9; color: #1b5e20; }

/* 10. CTA BUTTON */
.register-cta {
  text-align: center;
  margin: var(--space-xl) 0;
}

.btn-register {
  display: inline-block;
  padding: 14px 40px;
  background-color: var(--color-accent);
  color: var(--color-text-dark);
  font-family: var(--font-body);
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: var(--radius-pill);
  text-decoration: none;
  box-shadow: 0 4px 16px rgba(249,168,37,0.4);
  animation: pulse 2.5s ease infinite;
  transition: transform var(--transition-fast), filter var(--transition-fast);
}

.btn-register:hover {
  filter: brightness(1.08);
  transform: scale(1.05);
  animation-play-state: paused;
}

/* 11. SWIPER SLIDESHOW */
.swiper {
  width: 100%;
  aspect-ratio: 16 / 9;
  max-width: 800px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.swiper-slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.swiper-button-next,
.swiper-button-prev {
  color: var(--color-surface) !important;
  background-color: rgba(13,21,71,0.6);
  width: 40px !important;
  height: 40px !important;
  border-radius: var(--radius-circle);
  transition: background-color var(--transition-fast);
}

.swiper-button-next:hover,
.swiper-button-prev:hover {
  background-color: var(--color-navy);
}

.swiper-button-next::after,
.swiper-button-prev::after {
  font-size: 1rem !important;
  font-weight: 700;
}

.swiper-pagination-bullet-active {
  background-color: var(--color-accent) !important;
}

/* 12. POPUP FORM */
.popup-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.65);
  z-index: 1000;
  justify-content: center;
  align-items: center;
  padding: var(--space-sm);
}

.popup-content {
  background: var(--color-surface);
  padding: var(--space-lg) var(--space-lg);
  max-width: 460px;
  width: 100%;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  position: relative;
  animation: popupSlideUp 0.3s ease forwards;
}

.popup-content h2 {
  text-align: center;
  margin-bottom: var(--space-md);
  color: var(--color-navy);
  font-size: 1.5rem;
  letter-spacing: 1px;
}

.popup-content label {
  display: block;
  font-weight: 600;
  font-size: var(--fs-sm);
  color: var(--color-text-dark);
  margin-bottom: 6px;
}

.popup-content input {
  width: 100%;
  padding: 10px 14px;
  margin-bottom: var(--space-sm);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: var(--fs-body);
  font-family: var(--font-body);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  outline: none;
}

.popup-content input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(249,168,37,0.2);
}

.popup-content input[readonly] {
  background-color: #f3f4f6;
  color: var(--color-text-muted);
}

.popup-content button[type="submit"] {
  width: 100%;
  padding: 12px;
  background-color: var(--color-navy);
  color: var(--color-surface);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  font-weight: 700;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  letter-spacing: 0.5px;
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.popup-content button[type="submit"]:hover {
  background-color: var(--color-navy-light);
  transform: translateY(-1px);
}

.close-btn {
  position: absolute;
  top: 14px;
  right: 18px;
  font-size: 1.4rem;
  cursor: pointer;
  color: var(--color-text-muted);
  line-height: 1;
  transition: color var(--transition-fast);
}

.close-btn:hover {
  color: var(--color-text-dark);
}

/* 13. SOCIAL FIXED BUTTONS */
.social-fixed {
  position: fixed;
  top: 50%;
  right: 10px;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 10px;
  z-index: 999;
}

.social-btn {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-circle);
  display: flex;
  justify-content: center;
  align-items: center;
  text-decoration: none;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  color: var(--color-surface);
}

.social-btn img {
  width: 22px;
  height: 22px;
}

.social-btn:hover {
  transform: scale(1.15);
  box-shadow: var(--shadow-md);
}

.fb    { background-color: #1877f2; }
.zalo  { background-color: var(--color-navy); }
.phone { background-color: #22c55e; }

/* 14. FOOTER */
footer {
  background-color: var(--color-navy-dark);
  color: rgba(255,255,255,0.8);
  text-align: center;
  padding: var(--space-lg) var(--space-sm);
  font-size: var(--fs-sm);
  border-top: 2px solid var(--color-accent);
  margin-top: var(--space-lg);
}

/* 15. TOOL PAGES */

/* Chia nhóm */
.random-tool {
  font-family: var(--font-body);
  max-width: 700px;
  margin: var(--space-lg) auto;
  padding: 0 var(--space-sm);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.random-tool h1 {
  font-family: var(--font-heading);
  color: var(--color-navy);
  margin-bottom: var(--space-md);
  font-size: var(--fs-h2);
}

.random-tool input[type="file"] {
  margin-bottom: var(--space-sm);
}

.random-tool textarea {
  width: 100%;
  max-width: 420px;
  height: 220px;
  resize: vertical;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 10px;
  font-family: var(--font-body);
  font-size: var(--fs-sm);
  transition: border-color var(--transition-fast);
  outline: none;
}

.random-tool textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(249,168,37,0.15);
}

.random-tool label {
  font-weight: 600;
  color: var(--color-text-dark);
  margin-bottom: var(--space-xs);
}

.random-tool input[type="number"] {
  padding: 8px 12px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: var(--fs-body);
  font-family: var(--font-body);
  outline: none;
  transition: border-color var(--transition-fast);
}

.random-tool input[type="number"]:focus {
  border-color: var(--color-accent);
}

.random-tool button {
  background-color: var(--color-navy);
  color: var(--color-surface);
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: var(--fs-body);
  font-family: var(--font-body);
  font-weight: 600;
  cursor: pointer;
  margin: var(--space-xs);
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.random-tool button:hover {
  background-color: var(--color-navy-light);
  transform: translateY(-1px);
}

.random-tool .group-container {
  display: flex;
  gap: var(--space-sm);
  margin-top: var(--space-md);
  flex-wrap: wrap;
  width: 100%;
}

.random-tool .group {
  border: 2px solid var(--color-navy-light);
  border-radius: var(--radius-sm);
  padding: var(--space-sm);
  flex: 1;
  min-height: 180px;
  background-color: var(--color-surface);
  box-shadow: var(--shadow-sm);
}

.random-tool .group h3 {
  text-align: center;
  background: var(--color-navy);
  color: var(--color-surface);
  padding: 6px;
  border-radius: 4px;
  font-size: 1rem;
  margin-bottom: var(--space-xs);
}

.random-tool .student {
  padding: 4px 0;
  font-size: var(--fs-sm);
  border-bottom: 1px solid var(--color-border);
}

.random-tool .student:last-child {
  border-bottom: none;
}

/* Chọn ngẫu nhiên */
.random1-page {
  font-family: var(--font-body);
  background-color: var(--color-bg);
  padding: var(--space-lg) var(--space-sm);
}

.random1-page h1 {
  font-family: var(--font-heading);
  color: var(--color-navy);
  text-align: center;
  margin-bottom: var(--space-lg);
  font-size: var(--fs-h2);
}

.random1-page .container {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
  max-width: 960px;
  margin: 0 auto;
  padding: 0;
}

.random1-page .box {
  flex: 1;
  min-width: 280px;
  background: var(--color-surface);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  border-top: 3px solid var(--color-accent);
}

.random1-page .box h2 {
  color: var(--color-navy);
  font-size: 1.2rem;
  margin-bottom: var(--space-sm);
}

.random1-page .box label {
  display: block;
  font-weight: 600;
  font-size: var(--fs-sm);
  margin-bottom: 6px;
  color: var(--color-text-dark);
}

.random1-page textarea {
  width: 100%;
  height: 140px;
  padding: 10px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: var(--fs-sm);
  resize: none;
  outline: none;
  transition: border-color var(--transition-fast);
  display: block;
  margin-bottom: var(--space-xs);
}

.random1-page textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(249,168,37,0.15);
}

.random1-page input[type="number"] {
  width: 100%;
  padding: 10px 12px;
  margin-bottom: var(--space-xs);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: var(--fs-body);
  font-family: var(--font-body);
  outline: none;
  transition: border-color var(--transition-fast);
}

.random1-page input[type="number"]:focus {
  border-color: var(--color-accent);
}

.random1-page button {
  background-color: var(--color-navy);
  color: var(--color-surface);
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: var(--fs-body);
  font-family: var(--font-body);
  font-weight: 600;
  cursor: pointer;
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.random1-page button:hover {
  background-color: var(--color-navy-light);
  transform: translateY(-1px);
}

.random1-page .result {
  margin-top: var(--space-md);
  padding: var(--space-md);
  background-color: #fffde7;
  border: 2px solid var(--color-accent);
  border-radius: var(--radius-sm);
  font-size: 1.4rem;
  font-weight: 700;
  text-align: center;
  color: var(--color-navy);
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* 16. SCROLL ANIMATIONS */
.fade-in-section {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-in-section.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* 17. KEYFRAMES */
@keyframes marquee {
  from { transform: translateX(100%); }
  to   { transform: translateX(-100%); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes pulse {
  0%   { transform: scale(1);    box-shadow: 0 0 0 0 rgba(249,168,37,0.5); }
  50%  { transform: scale(1.03); box-shadow: 0 0 0 12px rgba(249,168,37,0); }
  100% { transform: scale(1);    box-shadow: 0 0 0 0 rgba(249,168,37,0); }
}

@keyframes popupSlideUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* 18. RESPONSIVE — Tablet (≤768px) */
@media (max-width: 768px) {
  .course-grid {
    grid-template-columns: 1fr;
  }

  .schedule-grid {
    grid-template-columns: 1fr;
  }

  .random-tool .group-container {
    flex-direction: column;
  }

  .random-tool textarea {
    max-width: 100%;
  }

  .random1-page .container {
    flex-direction: column;
  }

  .random1-page .box {
    min-width: unset;
  }

  .random1-page textarea {
    width: 100%;
  }
}

/* 19. RESPONSIVE — Mobile (≤480px) */
@media (max-width: 480px) {
  header {
    min-height: 80px;
    padding: var(--space-md) var(--space-sm);
  }

  header h1 {
    font-size: 1.8rem;
    letter-spacing: 1.5px;
  }

  header p {
    font-size: 0.9rem;
  }

  .announcement-marquee {
    font-size: var(--fs-sm);
    padding: 0.4rem 0;
  }

  .social-btn {
    width: 38px;
    height: 38px;
  }

  .social-btn img {
    width: 18px;
    height: 18px;
  }

  .swiper {
    border-radius: var(--radius-sm);
  }

  .btn-register {
    padding: 12px 28px;
    font-size: 1rem;
  }

  .popup-content {
    padding: var(--space-md);
  }

  nav {
    height: 48px;
  }

  nav a {
    padding: 0 10px;
    font-size: 0.85rem;
  }
}

/* 20. ACCESSIBILITY */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}