/* =====================================================================
   CATALYST CHEMISTRY TUITION - MODERN RESPONSIVE STYLESHEET
   ===================================================================== */

:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace;

  /* Palette */
  --color-primary: #0F172A;       /* Slate 900 */
  --color-primary-light: #1E293B; /* Slate 800 */
  --color-accent: #0284C7;        /* Sky 600 */
  --color-accent-hover: #0369A1;  /* Sky 700 */
  --color-teal: #0D9488;          /* Teal 600 */
  --color-teal-light: #CCFBF1;    /* Teal 100 */
  --color-amber: #F59E0B;         /* Amber 500 */
  --color-amber-light: #FEF3C7;   /* Amber 100 */
  --color-success: #10B981;       /* Emerald 500 */
  --color-danger: #EF4444;        /* Red 500 */

  /* Neutral Backgrounds & Texts */
  --bg-page: #F8FAFC;             /* Slate 50 */
  --bg-card: #FFFFFF;
  --bg-subtle: #F1F5F9;           /* Slate 100 */
  --text-main: #0F172A;
  --text-muted: #64748B;          /* Slate 500 */
  --text-light: #94A3B8;          /* Slate 400 */
  --border-color: #E2E8F0;        /* Slate 200 */
  --border-focus: #38BDF8;

  /* Elevations */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.09), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

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

/* Layout Utilities */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.container-narrow {
  max-width: 800px;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-primary);
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 0.75rem;
}

h1 { font-size: 2.75rem; letter-spacing: -0.03em; }
h2 { font-size: 2.1rem; letter-spacing: -0.02em; }
h3 { font-size: 1.45rem; }
h4 { font-size: 1.2rem; }

p {
  margin-bottom: 1rem;
  color: #334155;
}

.lead {
  font-size: 1.2rem;
  line-height: 1.7;
  color: var(--text-muted);
}

/* Section Spacing */
.section {
  padding: 5rem 0;
}

.section-alt {
  background-color: #FFFFFF;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.section-dark {
  background-color: var(--color-primary);
  color: #FFFFFF;
}

.section-dark h1, .section-dark h2, .section-dark h3 {
  color: #FFFFFF;
}

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 3.5rem auto;
}

.section-tag {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  background-color: #E0F2FE;
  padding: 0.3rem 0.8rem;
  border-radius: var(--radius-full);
  margin-bottom: 1rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.75rem 1.4rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent), #0284C7);
  color: #FFFFFF;
  box-shadow: 0 4px 12px rgba(2, 132, 199, 0.25);
}

.btn-primary:hover {
  background: linear-gradient(135deg, #0369A1, #075985);
  color: #FFFFFF;
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(2, 132, 199, 0.35);
}

.btn-secondary {
  background-color: #FFFFFF;
  color: var(--color-primary);
  border-color: var(--border-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background-color: var(--bg-subtle);
  border-color: #CBD5E1;
  color: var(--color-primary);
}

.btn-portal {
  background: linear-gradient(135deg, #0D9488, #0F766E);
  color: #FFFFFF;
  box-shadow: 0 4px 12px rgba(13, 148, 136, 0.25);
}

.btn-portal:hover {
  background: linear-gradient(135deg, #0F766E, #115E59);
  color: #FFFFFF;
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.btn-outline:hover {
  background: #E0F2FE;
}

.btn-sm {
  padding: 0.45rem 0.9rem;
  font-size: 0.85rem;
}

.btn-lg {
  padding: 0.9rem 1.8rem;
  font-size: 1.05rem;
}

/* =====================================================================
   HEADER & NAVIGATION
   ===================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 75px;
}

.brand-link {
  display: flex;
  align-items: center;
}

.brand-logo {
  height: 44px;
  width: auto;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
}

.nav-link {
  font-weight: 500;
  color: #475569;
  font-size: 0.95rem;
  position: relative;
  padding: 0.4rem 0;
}

.nav-link:hover, .nav-link.active {
  color: var(--color-accent);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--color-accent);
  border-radius: 2px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--color-primary);
}

/* =====================================================================
   HERO SECTION
   ===================================================================== */
.hero {
  padding: 5.5rem 0 4.5rem;
  background: radial-gradient(circle at 80% 20%, rgba(14, 165, 233, 0.08) 0%, transparent 50%),
              radial-gradient(circle at 10% 80%, rgba(20, 184, 166, 0.08) 0%, transparent 50%),
              var(--bg-page);
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 4rem;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: #0369A1;
  background: #E0F2FE;
  padding: 0.4rem 1rem;
  border-radius: var(--radius-full);
  margin-bottom: 1.5rem;
  border: 1px solid #BAE6FD;
}

.hero-title {
  font-size: 3.25rem;
  line-height: 1.15;
  margin-bottom: 1.25rem;
  color: var(--color-primary);
}

.hero-highlight {
  background: linear-gradient(135deg, #0284C7, #0D9488);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.hero-trust {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: #475569;
}

.hero-visual {
  position: relative;
}

.hero-card {
  background: #FFFFFF;
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--border-color);
  position: relative;
}

.hero-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.reaction-card {
  background: var(--bg-subtle);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-bottom: 1rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  border-left: 4px solid var(--color-accent);
}

/* =====================================================================
   STATS STRIP
   ===================================================================== */
.stats-strip {
  background-color: var(--color-primary);
  color: #FFFFFF;
  padding: 2.5rem 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  text-align: center;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: #38BDF8;
  display: block;
  line-height: 1.1;
  margin-bottom: 0.25rem;
}

.stat-label {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #94A3B8;
}

/* =====================================================================
   SERVICE CARDS (GCSE, A-Level, Undergrad)
   ===================================================================== */
.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.service-card {
  background: #FFFFFF;
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  transition: var(--transition);
  position: relative;
}

.service-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl);
  border-color: #BAE6FD;
}

.service-card.featured {
  border-color: var(--color-accent);
  box-shadow: 0 10px 25px -5px rgba(2, 132, 199, 0.15);
}

.badge-featured {
  position: absolute;
  top: -12px;
  right: 24px;
  background: var(--color-amber);
  color: #FFFFFF;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.service-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: #E0F2FE;
  color: var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
}

.service-card.featured .service-icon {
  background: #0284C7;
  color: #FFFFFF;
}

.service-title {
  font-size: 1.35rem;
  margin-bottom: 0.75rem;
}

.service-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
}

.service-features {
  list-style: none;
  margin-bottom: 2rem;
  margin-top: auto;
}

.service-feature-item {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  font-size: 0.9rem;
  color: #334155;
  margin-bottom: 0.6rem;
}

.service-feature-item svg {
  color: var(--color-teal);
  flex-shrink: 0;
  margin-top: 0.2rem;
}

/* =====================================================================
   PORTAL PREVIEW / LMS SHOWCASE
   ===================================================================== */
.lms-showcase {
  background: linear-gradient(180deg, #0F172A 0%, #1E293B 100%);
  color: #FFFFFF;
  padding: 5.5rem 0;
}

.lms-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3.5rem;
  align-items: center;
}

.lms-features-list {
  list-style: none;
  margin-top: 2rem;
}

.lms-feature-box {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
  background: rgba(255, 255, 255, 0.05);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.1);
  transition: var(--transition);
}

.lms-feature-box:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: #38BDF8;
}

.lms-feature-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: rgba(14, 165, 233, 0.2);
  color: #38BDF8;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.lms-screenshot {
  background: #020617;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
  overflow: hidden;
  padding: 1.5rem;
}

/* =====================================================================
   BLOG CARDS
   ===================================================================== */
.blog-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}

.blog-card {
  background: #FFFFFF;
  border-radius: var(--radius-lg);
  padding: 2rem;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.blog-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: #BAE6FD;
}

.blog-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.blog-tag {
  background-color: #F1F5F9;
  color: #475569;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-full);
  font-weight: 600;
}

.blog-title {
  font-size: 1.35rem;
  margin-bottom: 0.75rem;
  color: var(--color-primary);
}

.blog-card:hover .blog-title {
  color: var(--color-accent);
}

/* =====================================================================
   FORMS & INPUTS
   ===================================================================== */
.form-group {
  margin-bottom: 1.25rem;
}

.form-label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.4rem;
  color: var(--color-primary);
}

.form-control, .form-select, .form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  font-family: inherit;
  font-size: 0.95rem;
  color: var(--text-main);
  background-color: #FFFFFF;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  transition: var(--transition);
}

.form-control:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.2);
}

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

.alert {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-md);
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
}

.alert-success {
  background-color: #ECFDF5;
  color: #065F46;
  border: 1px solid #A7F3D0;
}

.alert-error {
  background-color: #FEF2F2;
  color: #991B1B;
  border: 1px solid #FECACA;
}

/* =====================================================================
   FOOTER
   ===================================================================== */
.site-footer {
  background-color: #0B1120;
  color: #94A3B8;
  padding: 4.5rem 0 2rem 0;
  margin-top: auto;
  border-top: 1px solid #1E293B;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 3.5rem;
}

.footer-brand p {
  color: #64748B;
  font-size: 0.9rem;
  margin-top: 1rem;
}

.footer-title {
  color: #FFFFFF;
  font-size: 1rem;
  margin-bottom: 1.25rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.6rem;
}

.footer-links a {
  color: #94A3B8;
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: #FFFFFF;
}

.footer-bottom {
  padding-top: 2rem;
  border-top: 1px solid #1E293B;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
  color: #64748B;
}

/* =====================================================================
   RESPONSIVE DESIGN
   ===================================================================== */
@media (max-width: 992px) {
  .hero-grid, .lms-grid {
    grid-template-columns: 1fr;
    gap: 3rem;
  }
  .services-grid {
    grid-template-columns: 1fr;
  }
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 75px;
    left: 0;
    right: 0;
    background: #FFFFFF;
    flex-direction: column;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
  }
  .nav-menu.is-open {
    display: flex;
  }
  .mobile-toggle {
    display: block;
  }
  .hero-title {
    font-size: 2.25rem;
  }
  .blog-grid {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
}