/* ============================================================
   Ritika Study Hub — Public Site CSS
   Apple-inspired, mobile-first, Bootstrap 5 base
   ============================================================ */

:root {
  --color-primary: #007AFF;
  --color-primary-dark: #0062CC;
  --color-accent: #FF9500;
  --color-bg: #F2F2F7;
  --color-card: #FFFFFF;
  --color-text: #1C1C1E;
  --color-muted: #6C6C70;
  --color-border: #E5E5EA;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 4px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.10);
  --nav-h: 62px;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
}

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

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

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

/* ── Nav ────────────────────────────────────────────────── */
.site-nav {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 500;
  height: var(--nav-h);
}

.site-nav .container {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 100%;
}

.brand {
  font-weight: 800;
  font-size: 1.125rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.brand i {
  color: var(--color-primary);
  font-size: 1.3rem;
}

.brand:hover {
  color: var(--color-primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
}

.nav-links a {
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-size: 0.875rem;
  font-weight: 500;
  transition: background 0.15s;
}

.nav-links a:hover {
  background: var(--color-bg);
  color: var(--color-primary);
}

.nav-search {
  display: flex;
  align-items: center;
  background: var(--color-bg);
  border-radius: 100px;
  overflow: hidden;
  border: 1.5px solid var(--color-border);
  flex-shrink: 0;
}

.nav-search input {
  border: none;
  background: none;
  padding: 7px 14px;
  font-size: 0.875rem;
  outline: none;
  width: 220px;
}

.nav-search button {
  background: none;
  border: none;
  padding: 7px 14px;
  color: var(--color-muted);
  cursor: pointer;
}

.nav-search button:hover {
  color: var(--color-primary);
}

.nav-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
  color: var(--color-text);
  margin-left: auto;
}

/* ── Hero ───────────────────────────────────────────────── */
.site-hero {
  background: linear-gradient(135deg, #007AFF 0%, #0055C8 100%);
  color: #fff;
  padding: 80px 0 60px;
  text-align: center;
}

.site-hero h1 {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 800;
  margin-bottom: 16px;
}

.site-hero p {
  font-size: 1.125rem;
  opacity: 0.85;
  max-width: 600px;
  margin: 0 auto 32px;
}

.hero-search {
  display: flex;
  align-items: center;
  max-width: 540px;
  margin: 0 auto;
  background: #fff;
  border-radius: 100px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.hero-search input {
  border: none;
  outline: none;
  flex: 1;
  padding: 14px 20px;
  font-size: 1rem;
  color: var(--color-text);
}

.hero-search button {
  background: var(--color-primary);
  border: none;
  color: #fff;
  padding: 16px 24px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.9rem;
  transition: background 0.15s;
}

.hero-search button:hover {
  background: var(--color-primary-dark);
}

/* ── Page hero (inner pages) ────────────────────────────── */
.page-hero {
  background: linear-gradient(135deg, #007AFF 0%, #0055C8 100%);
  color: #fff;
  padding: 40px 0;
}

.page-hero h1 {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 800;
  margin-bottom: 8px;
}

.page-hero p {
  opacity: 0.85;
  margin: 0;
}

.page-hero .breadcrumb {
  margin-bottom: 16px;
}

.breadcrumb-item a {
  color: rgba(255, 255, 255, 0.75);
}

.breadcrumb-item.active {
  color: #fff;
}

.breadcrumb-item+.breadcrumb-item::before {
  color: rgba(255, 255, 255, 0.5);
}

.hero-icon {
  font-size: 3rem;
}

.hero-icon-img {
  width: 64px;
  height: 64px;
  object-fit: cover;
  border-radius: var(--radius-md);
}

/* ── Sections ───────────────────────────────────────────── */
.section-pad {
  padding: 56px 0;
}

.section-heading {
  font-size: 1.375rem;
  font-weight: 800;
  margin-bottom: 28px;
}

/* ── Category cards ─────────────────────────────────────── */
.category-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 24px 16px;
  background: var(--color-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--color-border);
  text-align: center;
  color: var(--color-text);
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
}

.category-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.category-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, #EBF4FF, #D6EAFF);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--color-primary);
  overflow: hidden;
}

.category-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.category-name {
  line-height: 1.3;
}

/* ── Article / content cards ────────────────────────────── */
.article-card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--color-border);
  overflow: hidden;
  transition: transform 0.2s, box-shadow 0.2s;
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.article-card img {
  width: 100%;
  height: 180px;
  object-fit: cover;
}

.article-card-body {
  padding: 16px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.article-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-text);
}

.article-card p {
  font-size: 0.8rem;
  color: var(--color-muted);
  flex: 1;
}

/* ── Footer ─────────────────────────────────────────────── */
.site-footer {
  background: #1C1C1E;
  color: rgba(255, 255, 255, 0.75);
  padding: 48px 0 24px;
}

.site-footer h5,
.site-footer h6 {
  color: #fff;
  font-weight: 700;
  margin-bottom: 14px;
}

.site-footer p {
  font-size: 0.875rem;
}

.site-footer a {
  display: block;
  color: rgba(255, 255, 255, 0.65);
  font-size: 0.875rem;
  margin-bottom: 6px;
}

.site-footer a:hover {
  color: #fff;
}

.site-footer hr {
  border-color: rgba(255, 255, 255, 0.1);
  margin: 24px 0 16px;
}

.site-footer .small {
  color: rgba(255, 255, 255, 0.4);
}

.social-links {
  display: flex;
  gap: 12px;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  font-size: 1.1rem;
  color: #fff;
  transition: background 0.15s;
}

.social-links a:hover {
  background: var(--color-primary);
}

/* ── Dark mode ──────────────────────────────────────────── */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #000000;
    --color-card: #1C1C1E;
    --color-text: #F2F2F7;
    --color-muted: #8E8E93;
    --color-border: #38383A;
  }

  .site-nav {
    background: rgba(28, 28, 30, 0.85);
  }

  .brand {
    color: #F2F2F7;
  }

  .nav-links a {
    color: #F2F2F7;
  }

  .nav-search {
    background: #38383A;
    border-color: #48484A;
  }

  .nav-search input {
    color: #F2F2F7;
  }

  .hero-search input {
    color: #1C1C1E;
  }

  .category-icon {
    background: linear-gradient(135deg, #1C2B3A, #1A3A5C);
  }

  .article-card h3 {
    color: #F2F2F7;
  }
}

/* ── Mobile nav ─────────────────────────────────────────── */
@media (max-width: 991.98px) {
  .nav-links {
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: var(--color-card);
    flex-direction: column;
    align-items: stretch;
    padding: 12px 0;
    gap: 0;
    box-shadow: var(--shadow-md);
    display: none;
    z-index: 400;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    padding: 12px 20px;
    border-radius: 0;
  }
}