/* ============================================
   OET Center - Custom Styles (ASP.NET Web Forms)
   Sleek, modern, serious but friendly design
   Compatible with older ASP.NET versions
   ============================================ */

:root {
  --primary: #0F4C5C;
  --primary-dark: #0A3640;
  --accent: #2DD4BF;
  --accent-dark: #14B8A6;
  --text-primary: #1E293B;
  --text-secondary: #64748B;
  --bg-light: #F8FAFC;
  --bg-white: #FFFFFF;
  --shadow-sm: 0 1px 2px 0 rgb(15 76 92 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(15 76 92 / 0.1), 0 2px 4px -2px rgb(15 76 92 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(15 76 92 / 0.1), 0 4px 6px -4px rgb(15 76 92 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(15 76 92 / 0.1), 0 8px 10px -6px rgb(15 76 92 / 0.1);
  --transition-fast: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --radius: 12px;
  --radius-sm: 8px;
}

/* Base & Typography */
body {
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--text-primary);
  line-height: 1.7;
  background-color: var(--bg-light);
}

h1, h2, h3, h4, h5 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 { font-size: clamp(2.5rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.75rem, 4vw, 2.25rem); }

.lead {
  font-size: 1.15rem;
  color: var(--text-secondary);
}

/* Smooth everything */
a, button, .btn, .card, .nav-link, .dropdown-item {
  transition: var(--transition-base);
}

/* Navbar */
.navbar {
  background-color: var(--bg-white);
  box-shadow: var(--shadow-md);
  padding-top: 0.75rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid #E2E8F0;
}

.navbar-brand {
  font-weight: 800;
  font-size: 1.65rem;
  color: var(--primary) !important;
  letter-spacing: -0.025em;
}

.nav-link {
  color: var(--text-primary) !important;
  font-weight: 500;
  padding-left: 1rem !important;
  padding-right: 1rem !important;
  position: relative;
}

.nav-link:hover {
  color: var(--primary) !important;
}

.nav-link.active {
  color: var(--primary) !important;
  font-weight: 600;
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 1rem;
  right: 1rem;
  height: 2px;
  background-color: var(--accent);
  border-radius: 2px;
}

.dropdown-menu {
  border: none;
  box-shadow: var(--shadow-lg);
  border-radius: var(--radius);
  padding: 0.5rem 0;
  margin-top: 0.5rem;
  animation: dropdownFade 0.2s ease forwards;
}

@keyframes dropdownFade {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

.dropdown-item {
  padding: 0.6rem 1.25rem;
  font-weight: 500;
  color: var(--text-primary);
}

.dropdown-item:hover {
  background-color: #F0FDFA;
  color: var(--primary);
}

/* Buttons */
.btn {
  font-weight: 600;
  border-radius: var(--radius-sm);
  padding: 0.65rem 1.5rem;
  box-shadow: var(--shadow-sm);
}

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

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

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

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

.btn-outline-primary {
  color: var(--primary);
  border-color: var(--primary);
}

.btn-outline-primary:hover {
  background-color: var(--primary);
  color: white;
  transform: translateY(-1px);
}

/* Hero / Billboard */
.hero {
  position: relative;
  min-height: 620px;
  display: flex;
  align-items: center;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  border-radius: 0 0 var(--radius) var(--radius);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to right,
    rgba(15, 76, 92, 0.75) 0%,
    rgba(15, 76, 92, 0.55) 45%,
    rgba(15, 76, 92, 0.35) 70%
  );
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 620px;
}

.hero h1 {
  color: white;
  text-shadow: 0 2px 10px rgba(0,0,0,0.3);
  margin-bottom: 1.25rem;
}

.hero .lead {
  color: rgba(255,255,255,0.92);
  margin-bottom: 2rem;
}

/* Feature Cards */
.feature-card {
  background: var(--bg-white);
  border: 1px solid #E2E8F0;
  border-radius: var(--radius);
  padding: 2rem 1.75rem;
  height: 100%;
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: #CBD5E1;
}

.feature-card .icon-wrapper {
  width: 58px;
  height: 58px;
  background: linear-gradient(135deg, #E0F2FE 0%, #CCFBF1 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
}

.feature-card .icon-wrapper i {
  font-size: 1.65rem;
  color: var(--primary);
}

.feature-card h3 {
  font-size: 1.35rem;
  margin-bottom: 0.85rem;
}

/* Cards */
.card {
  border: none;
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  transition: var(--transition-base);
  background: var(--bg-white);
}

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

.card-body {
  padding: 1.5rem;
}

/* Forms */
.form-control, .form-select {
  border-radius: var(--radius-sm);
  border: 1px solid #CBD5E1;
  padding: 0.65rem 1rem;
  transition: var(--transition-fast);
}

.form-control:focus, .form-select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(45, 212, 191, 0.15);
}

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

/* Footer */
footer {
  background-color: var(--primary);
  color: rgba(255,255,255,0.92);
  padding-top: 3rem;
  padding-bottom: 2rem;
}

footer h5 {
  color: white;
  font-weight: 700;
  margin-bottom: 1.25rem;
}

footer a {
  color: rgba(255,255,255,0.85);
  text-decoration: none;
}

footer a:hover {
  color: white;
  text-decoration: underline;
}

.footer-icon {
  width: 20px;
  display: inline-block;
  margin-right: 0.5rem;
  opacity: 0.9;
}

/* Utility */
.section-title {
  position: relative;
  display: inline-block;
  margin-bottom: 2.5rem;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 48px;
  height: 3px;
  background: linear-gradient(to right, var(--accent), var(--primary));
  border-radius: 3px;
}

.tutor-card .avatar {
  width: 110px;
  height: 110px;
  object-fit: cover;
  border: 4px solid #F1F5F9;
  box-shadow: var(--shadow-md);
  transition: var(--transition-base);
}

.tutor-card:hover .avatar {
  transform: scale(1.03);
  box-shadow: var(--shadow-lg);
}

section {
  scroll-margin-top: 80px;
}

/* Auth Pages */
.auth-card {
  max-width: 460px;
  margin: 0 auto;
  box-shadow: var(--shadow-xl);
  border-radius: var(--radius);
}

.auth-header {
  text-align: center;
  margin-bottom: 2rem;
}

.auth-header .logo {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary);
}

/* Responsive */
@media (max-width: 991.98px) {
  .hero {
    min-height: 520px;
    border-radius: 0;
  }
}