/* NTU Info - Shared Styles
 * Common styles used across all pages
 */

/* External font import removed to avoid CDN dependency.
   Font stack still prefers Inter if available locally. */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 100px;
}

body {
  font-family: var(--font-sans);
  line-height: var(--leading-normal);
  color: var(--gray-700);
  background: linear-gradient(180deg, var(--page-tint) 0%, var(--page-tint-alt) 100%);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  font-weight: 700;
  line-height: var(--leading-tight);
  color: var(--gray-900);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-base); }

p {
  margin-bottom: var(--spacing-md);
  color: var(--gray-700);
}

main {
  padding-bottom: var(--spacing-3xl);
}

.page-hero {
  margin: var(--spacing-xl) 0 var(--spacing-xl);
  padding: clamp(1rem, 2.4vw, 1.65rem);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(0, 54, 134, 0.2);
  background: linear-gradient(120deg, #003a8f 0%, #0d56ba 60%, #3175d1 100%);
  color: var(--white);
  box-shadow: 0 16px 36px rgba(0, 50, 130, 0.16);
}

.page-hero-title {
  margin: 0;
  color: var(--white);
  font-size: clamp(1.55rem, 3.3vw, 2.1rem);
}

.page-hero-description,
.page-hero p {
  margin: var(--spacing-sm) 0 0;
  color: rgba(255, 255, 255, 0.92);
  max-width: 70ch;
}

/* Fixed bottom promo banner */
.has-floating-promo {
  /* Keep scrollable content clear of the fixed banner so bottom cards/footer stay readable. */
  padding-bottom: calc(var(--floating-promo-height) + env(safe-area-inset-bottom, 0px) + var(--spacing-lg));
}

.floating-promo {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: var(--z-fixed);
  padding-bottom: env(safe-area-inset-bottom, 0px);
  pointer-events: none;
}

.floating-promo-link {
  display: block;
  width: min(100%, 1200px);
  margin: 0 auto;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  overflow: hidden;
  box-shadow: 0 -12px 24px rgba(15, 23, 42, 0.24);
  pointer-events: auto;
}

.floating-promo-link:hover,
.floating-promo-link:focus-visible {
  text-decoration: none;
}

.floating-promo-image {
  display: block;
  width: 100%;
  height: var(--floating-promo-height);
  object-fit: cover;
}

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

a:hover,
a:focus {
  color: var(--ntu-blue-light);
  text-decoration: underline;
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--ntu-red);
  outline-offset: 2px;
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--ntu-red);
  color: var(--white);
  padding: var(--spacing-sm) var(--spacing-md);
  z-index: var(--z-modal);
  transition: top 0.3s;
}

.skip-link:focus {
  top: 0;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Header */
.header {
  background: rgba(249, 251, 255, 0.92);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--gray-200);
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  padding: 0.55rem 0;
  min-height: 72px;
}

.header-container {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-lg);
}

.logo-section {
  text-align: left;
}

.logo-title {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--ntu-blue);
  margin: 0;
}

.logo-home-link {
  display: inline-flex;
  align-items: center;
  min-height: 2.25rem;
  padding: 0.2rem 0.15rem;
  color: inherit;
  text-decoration: none;
}

.logo-home-link:hover,
.logo-home-link:focus-visible {
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.logo-subtitle {
  display: none;
}

/* Navigation */
.main-nav ul {
  display: flex;
  align-items: center;
  list-style: none;
  gap: var(--spacing-lg);
}

.main-nav a {
  color: var(--gray-700);
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  transition: var(--transition);
}

.main-nav a:hover,
.main-nav a:focus,
.main-nav a[aria-current="page"] {
  color: var(--ntu-blue);
  background: var(--ntu-blue-lighter);
  text-decoration: none;
}

/* Banner tabs (accessible navigation) */
.banner-nav {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: var(--spacing-sm);
  position: relative;
}

.banner-tabs {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  flex-wrap: wrap;
  justify-content: flex-end;
}

.banner-tab {
  appearance: none;
  border: none;
  background: transparent;
  color: var(--gray-700);
  font-weight: 600;
  padding: 0.35rem 0.6rem 0.55rem;
  border-radius: 0;
  cursor: pointer;
  transition: color 0.2s ease;
  position: relative;
  min-height: 40px;
}

.banner-tab::after {
  content: '';
  position: absolute;
  left: 25%;
  width: 50%;
  bottom: 0.15rem;
  height: 2px;
  background: var(--ntu-red);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.2s ease;
}

.banner-tab:hover {
  color: var(--ntu-blue);
}

.banner-tab.is-active,
.banner-tab[aria-selected="true"],
.banner-tab:hover,
.banner-tab:focus-visible {
  color: var(--ntu-red);
}

.banner-tab.is-active::after,
.banner-tab[aria-selected="true"]::after,
.banner-tab:hover::after,
.banner-tab:focus-visible::after {
  transform: scaleX(1);
}

.banner-panels {
  width: auto;
  max-width: 520px;
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  z-index: var(--z-dropdown);
  pointer-events: none;
}

.banner-panels.is-open {
  pointer-events: auto;
}

.banner-panel {
  background: rgba(255, 255, 255, 0.99);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: var(--spacing-sm);
  min-width: 180px; /* sensible default when JS sizing isn't available */
}

.banner-panel[hidden] {
  display: none;
}

.banner-panel-list {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}

.banner-panel-list a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  color: var(--gray-700);
  font-weight: 500;
  text-decoration: none;
}

.banner-panel-list a:hover,
.banner-panel-list a:focus {
  background: var(--ntu-blue-lighter);
  color: var(--ntu-blue);
  text-decoration: none;
}

a.is-disabled,
.banner-panel-list a[aria-disabled="true"] {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}

/* Dropdown menu */
.dropdown {
  position: relative;
}

.dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  min-width: 220px;
  padding: var(--spacing-sm);
  z-index: var(--z-dropdown);
  flex-direction: column;
  gap: 0;
}

/* Hover-only dropdown interaction intentionally disabled.
   Use the banner tab system instead (keyboard + touch operable). */

.dropdown-menu li {
  width: 100%;
}

.dropdown-menu a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  white-space: nowrap;
}

/* Academic Tools Panel - Sticky sidebar */
.academic-tools-panel {
  position: fixed;
  top: 100px;
  right: var(--spacing-md);
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  padding: var(--spacing-lg);
  width: 220px;
  z-index: var(--z-fixed);
  transition: var(--transition);
}

.academic-tools-panel h3 {
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--gray-500);
  margin-bottom: var(--spacing-md);
}

.academic-tools-panel ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.academic-tools-panel a {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  color: var(--gray-700);
  font-weight: 500;
  transition: var(--transition);
}

.academic-tools-panel a:hover,
.academic-tools-panel a:focus {
  background: var(--ntu-blue-lighter);
  color: var(--ntu-blue);
  text-decoration: none;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-lg);
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn:focus-visible {
  outline: 2px solid var(--ntu-red);
  outline-offset: 2px;
}

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

.btn-primary:hover {
  background: var(--ntu-red-light);
  color: var(--white);
  text-decoration: none;
}

.btn-secondary {
  background: var(--ntu-blue);
  color: var(--white);
  border: 1px solid var(--ntu-blue);
}

.btn-secondary:hover {
  background: var(--ntu-blue-light);
  color: var(--white);
}

.btn-danger {
  background: #a4161a;
  color: var(--white);
}

.btn-danger:hover {
  background: #8b0000;
}

/* Cards */
.card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
  margin-bottom: var(--spacing-lg);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.card-kicker {
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: var(--text-xs);
  color: var(--gray-500);
  margin: 0;
}

/* Form elements */
.form-field {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  flex: 1;
  min-width: 160px;
}

.form-field label {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--gray-600);
}

.form-field input,
.form-field select,
.form-field textarea {
  padding: var(--spacing-sm) var(--spacing-md);
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: var(--text-base);
  transition: var(--transition);
}

.form-field input:focus,
.form-field select:focus,
.form-field textarea:focus {
  border-color: var(--ntu-blue);
  outline: none;
  box-shadow: 0 0 0 3px var(--ntu-blue-lighter);
}

/* Footer */
.site-footer {
  background: linear-gradient(135deg, var(--gray-900) 0%, var(--gray-800) 100%);
  color: var(--white);
  padding: var(--spacing-3xl) 0 var(--spacing-xl);
  margin-top: var(--spacing-3xl);
}

.footer-content {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: var(--spacing-2xl);
}

.footer-branding h3 {
  color: var(--white);
  margin-bottom: var(--spacing-sm);
}

.footer-branding .tagline {
  color: var(--gray-400);
  margin-bottom: var(--spacing-md);
}

.footer-branding .copyright {
  font-size: var(--text-sm);
  color: var(--gray-500);
}

.footer-branding .copyright a {
  color: var(--ntu-blue-light);
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-xl);
}

.footer-column h4 {
  color: var(--gray-300);
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--spacing-md);
}

.footer-column ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer-column a {
  color: var(--gray-400);
  font-size: var(--text-sm);
  transition: var(--transition);
}

.footer-column a:hover {
  color: var(--white);
}

.footer-disclaimer {
  max-width: var(--container-xl);
  margin: var(--spacing-2xl) auto 0;
  padding: var(--spacing-lg) var(--spacing-md) 0;
  border-top: 1px solid var(--gray-700);
  text-align: center;
}

.footer-disclaimer p {
  color: var(--gray-500);
  font-size: var(--text-sm);
}

/* Utility classes */
.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;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }

/* Responsive breakpoints */
@media (max-width: 1280px) {
  .academic-tools-panel {
    width: 200px;
    padding: var(--spacing-md);
  }
}

@media (max-width: 1024px) {
  .academic-tools-panel {
    display: none;
  }

  .footer-content {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 768px) {
  .header {
    min-height: 0;
  }

  .header-container {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-md);
  }

  .main-nav ul {
    flex-wrap: wrap;
    justify-content: center;
  }

  .footer-links {
    grid-template-columns: 1fr;
  }

  .page-hero {
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
  }

  :root {
    --floating-promo-height: 64px;
  }

  h1 { font-size: var(--text-3xl); }
  h2 { font-size: var(--text-2xl); }
  h3 { font-size: var(--text-xl); }

  .banner-nav,
  .banner-tabs {
    align-items: flex-start;
    justify-content: flex-start;
    width: 100%;
  }

  .banner-panels {
    left: 0;
    right: auto;
    max-width: min(100vw - 2rem, 420px);
  }
}

@media (max-width: 320px) {
  .container {
    padding: 0 var(--spacing-sm);
  }

  .card {
    padding: var(--spacing-md);
  }
}