/* ================================================
   IELTS Band 7 RDC Institute - Main Stylesheet
   Modular CSS Architecture
   ================================================ */

/* === CSS Variables (Design Tokens) === */
:root {
  /* Colors */
  --color-primary: #1a73e8;
  --color-primary-dark: #1557b0;
  --color-primary-light: #e8f0fe;
  --color-secondary: #34a853;
  --color-accent: #ea4335;
  --color-warning: #fbbc04;

  /* Neutrals */
  --color-bg: #ffffff;
  --color-bg-alt: #f8f9fa;
  --color-bg-dark: #202124;
  --color-text: #202124;
  --color-text-secondary: #5f6368;
  --color-text-light: #ffffff;
  --color-border: #dadce0;
  --color-border-light: #e8eaed;

  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-heading: 'Poppins', var(--font-primary);

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* 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 rgba(0,0,0,0.07);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.15);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;

  /* Layout */
  --container-max: 1200px;
  --container-padding: 1.5rem;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-primary);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul, ol {
  list-style: none;
}

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

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

/* === Layout Components === */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--space-3xl) 0;
}

.section--alt {
  background-color: var(--color-bg-alt);
}

.section__header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.section__title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  margin-bottom: var(--space-sm);
}

.section__subtitle {
  color: var(--color-text-secondary);
  font-size: 1.125rem;
  max-width: 600px;
  margin: 0 auto;
}

/* === Grid System === */
.grid {
  display: grid;
  gap: var(--space-lg);
}

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

@media (max-width: 1024px) {
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
}

/* === Navigation === */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--color-bg);
  box-shadow: var(--shadow-sm);
  z-index: 1000;
  padding: var(--space-md) 0;
}

.navbar__container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar__logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
}

.navbar__logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
}

.navbar__menu {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.navbar__link {
  color: var(--color-text);
  font-weight: 500;
  padding: var(--space-sm) 0;
  position: relative;
}

.navbar__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width var(--transition-normal);
}

.navbar__link:hover::after,
.navbar__link--active::after {
  width: 100%;
}

.navbar__cta {
  background: var(--color-primary);
  color: white !important;
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-full);
  font-weight: 600;
}

.navbar__cta:hover {
  background: var(--color-primary-dark);
}

.navbar__toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
}

@media (max-width: 768px) {
  .navbar__menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    flex-direction: column;
    padding: var(--space-lg);
    box-shadow: var(--shadow-md);
    gap: var(--space-md);
  }

  .navbar__menu--open {
    display: flex;
  }

  .navbar__toggle {
    display: block;
  }
}

/* === Hero Section === */
.hero {
  padding: calc(80px + var(--space-3xl)) 0 var(--space-3xl);
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, var(--color-primary-light) 100%);
  min-height: 80vh;
  display: flex;
  align-items: center;
}

.hero__container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.hero__content {
  max-width: 560px;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  background: white;
  padding: var(--space-xs) var(--space-md);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-secondary);
  margin-bottom: var(--space-lg);
  box-shadow: var(--shadow-sm);
}

.hero__title {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  margin-bottom: var(--space-lg);
  line-height: 1.1;
}

.hero__title-accent {
  color: var(--color-primary);
}

.hero__description {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xl);
}

.hero__actions {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.hero__visual {
  position: relative;
}

.hero__stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
}

.hero__stat {
  text-align: center;
}

.hero__stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
}

.hero__stat-label {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

@media (max-width: 968px) {
  .hero__container {
    grid-template-columns: 1fr;
  }

  .hero__visual {
    display: none;
  }
}

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn--primary {
  background: var(--color-primary);
  color: white;
}

.btn--primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn--secondary {
  background: white;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

.btn--secondary:hover {
  background: var(--color-primary-light);
}

.btn--success {
  background: var(--color-secondary);
  color: white;
}

.btn--sm {
  padding: var(--space-sm) var(--space-lg);
  font-size: 0.875rem;
}

.btn--lg {
  padding: var(--space-lg) var(--space-2xl);
  font-size: 1.125rem;
}

/* === Cards === */
.card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

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

.card__icon {
  width: 60px;
  height: 60px;
  background: var(--color-primary-light);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: var(--space-lg);
}

.card__title {
  font-size: 1.25rem;
  margin-bottom: var(--space-sm);
}

.card__text {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
}

/* === Course Cards === */
.course-card {
  position: relative;
  background: var(--color-bg);
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.course-card:hover {
  box-shadow: var(--shadow-xl);
  transform: translateY(-8px);
}

.course-card__image {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.course-card__content {
  padding: var(--space-xl);
}

.course-card__tag {
  display: inline-block;
  background: var(--color-primary-light);
  color: var(--color-primary);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  margin-bottom: var(--space-sm);
}

.course-card__title {
  font-size: 1.25rem;
  margin-bottom: var(--space-sm);
}

.course-card__description {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
  margin-bottom: var(--space-lg);
}

.course-card__meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border-light);
}

.course-card__duration {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}

.course-card__price {
  font-weight: 700;
  color: var(--color-secondary);
  font-size: 1.125rem;
}

/* === Stats Section === */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
}

.stats__item {
  text-align: center;
  padding: var(--space-xl);
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.stats__value {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-xs);
}

.stats__label {
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
}

@media (max-width: 768px) {
  .stats {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* === Reviews === */
.review-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
}

.review-card__header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.review-card__avatar {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  object-fit: cover;
}

.review-card__info {
  flex: 1;
}

.review-card__name {
  font-weight: 600;
  margin-bottom: var(--space-xs);
}

.review-card__date {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

.review-card__rating {
  display: flex;
  gap: 2px;
}

.review-card__stars {
  color: var(--color-warning);
}

.review-card__text {
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* === Gallery === */
.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.gallery__item {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  aspect-ratio: 4/3;
  cursor: pointer;
}

.gallery__item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.gallery__item:hover img {
  transform: scale(1.05);
}

.gallery__overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(0,0,0,0.7), transparent);
  opacity: 0;
  transition: opacity var(--transition-normal);
  display: flex;
  align-items: flex-end;
  padding: var(--space-lg);
}

.gallery__item:hover .gallery__overlay {
  opacity: 1;
}

/* === Contact Info === */
.contact-info {
  display: grid;
  gap: var(--space-lg);
}

.contact-info__item {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-lg);
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.contact-info__icon {
  width: 56px;
  height: 56px;
  background: var(--color-primary-light);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
}

.contact-info__content {
  flex: 1;
}

.contact-info__label {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xs);
}

.contact-info__value {
  font-weight: 600;
}

.contact-info__value a {
  color: var(--color-primary);
}

/* === Map === */
.map-container {
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.map-container iframe {
  width: 100%;
  height: 400px;
  border: none;
}

/* === Footer === */
.footer {
  background: var(--color-bg-dark);
  color: var(--color-text-light);
  padding: var(--space-3xl) 0 var(--space-xl);
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer__brand {
  max-width: 300px;
}

.footer__logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 700;
  font-size: 1.25rem;
  margin-bottom: var(--space-lg);
}

.footer__logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.footer__description {
  color: #9aa0a6;
  font-size: 0.9375rem;
  line-height: 1.7;
}

.footer__title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-lg);
}

.footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer__link {
  color: #9aa0a6;
  font-size: 0.9375rem;
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: white;
}

.footer__bottom {
  padding-top: var(--space-xl);
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  color: #9aa0a6;
}

.footer__social {
  display: flex;
  gap: var(--space-md);
}

.footer__social-link {
  width: 40px;
  height: 40px;
  background: rgba(255,255,255,0.1);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  transition: all var(--transition-fast);
}

.footer__social-link:hover {
  background: var(--color-primary);
  transform: translateY(-2px);
}

@media (max-width: 968px) {
  .footer__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 576px) {
  .footer__grid {
    grid-template-columns: 1fr;
  }

  .footer__bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }
}

/* === Lightbox === */
.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.95);
  z-index: 2000;
  display: none;
  align-items: center;
  justify-content: center;
}

.lightbox--open {
  display: flex;
}

.lightbox__content {
  max-width: 90vw;
  max-height: 90vh;
}

.lightbox__close {
  position: absolute;
  top: 20px;
  right: 20px;
  background: rgba(255,255,255,0.1);
  border: none;
  color: white;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  cursor: pointer;
  font-size: 1.5rem;
  transition: background var(--transition-fast);
}

.lightbox__close:hover {
  background: rgba(255,255,255,0.2);
}

/* === Forms === */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-label {
  display: block;
  font-weight: 500;
  margin-bottom: var(--space-sm);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: var(--space-md);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: white;
  transition: border-color var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

/* === Page Header === */
.page-header {
  background: linear-gradient(135deg, var(--color-bg-alt), var(--color-primary-light));
  padding: calc(80px + var(--space-2xl)) 0 var(--space-2xl);
  text-align: center;
}

.page-header__title {
  font-size: clamp(2rem, 4vw, 3rem);
  margin-bottom: var(--space-md);
}

.page-header__breadcrumb {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  color: var(--color-text-secondary);
  font-size: 0.9375rem;
}

.page-header__breadcrumb a {
  color: var(--color-primary);
}

/* === Utilities === */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-1 { margin-top: var(--space-sm); }
.mt-2 { margin-top: var(--space-md); }
.mt-3 { margin-top: var(--space-lg); }
.mt-4 { margin-top: var(--space-xl); }
.mt-5 { margin-top: var(--space-2xl); }

.mb-1 { margin-bottom: var(--space-sm); }
.mb-2 { margin-bottom: var(--space-md); }
.mb-3 { margin-bottom: var(--space-lg); }
.mb-4 { margin-bottom: var(--space-xl); }
.mb-5 { margin-bottom: var(--space-2xl); }

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

/* === Animations === */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideIn {
  from { transform: translateX(-20px); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

.animate-fade-in {
  animation: fadeIn 0.6s ease forwards;
}

.animate-slide-in {
  animation: slideIn 0.4s ease forwards;
}

/* === Loading States === */
.skeleton {
  background: linear-gradient(90deg, var(--color-bg-alt) 25%, #e8eaed 50%, var(--color-bg-alt) 75%);
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s infinite;
  border-radius: var(--radius-md);
}

@keyframes skeleton-loading {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* === Badges === */
.badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
}

.badge--primary {
  background: var(--color-primary);
  color: white;
}

.badge--success {
  background: var(--color-secondary);
  color: white;
}

.badge--warning {
  background: var(--color-warning);
  color: var(--color-text);
}

/* === Rating Stars === */
.rating {
  display: flex;
  align-items: center;
  gap: 2px;
}

.rating__stars {
  color: var(--color-warning);
}

.rating__value {
  font-weight: 700;
  margin-left: var(--space-xs);
}

.rating__count {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  margin-left: var(--space-xs);
}