/* ==========================================================================
   Koit Academy — Design Tokens
   ========================================================================== */
:root {
  --color-primary: #262421;
  --color-primary-dark: #100F0D;
  --color-primary-light: #F3F1EA;
  --color-accent: #B08D3F;
  --color-white: #FFFFFF;
  --color-text: #1F2937;
  --color-gray: #6B7280;
  --color-border: #E5E7EB;
  --color-footer-bg: #1B1917;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  --container-width: 1200px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.08);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.10);
  --shadow-lg: 0 16px 40px rgba(15, 23, 42, 0.14);
  --header-height: 72px;
}

/* ==========================================================================
   Reset
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: var(--header-height); }
body, h1, h2, h3, p, ul, ol, figure { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; background: none; border: none; }

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 { font-weight: 700; line-height: 1.2; }

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

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-primary);
  color: var(--color-white);
  padding: 12px 20px;
  z-index: 1000;
  border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.container {
  width: 100%;
  max-width: var(--container-width);
  margin-inline: auto;
  padding-inline: 20px;
}
.container-narrow { max-width: 760px; }

.section { padding-block: 64px; }

.section-title {
  font-size: clamp(1.6rem, 1.3rem + 1.3vw, 2.25rem);
  text-align: center;
  margin-bottom: 40px;
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 2px solid transparent;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease, transform 0.15s ease;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

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

.btn-outline {
  background: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.btn-outline:hover {
  background: var(--color-primary-light);
}

.btn-white {
  background: var(--color-white);
  color: var(--color-primary-dark);
  border-color: var(--color-white);
}
.btn-white:hover {
  background: var(--color-text);
  color: var(--color-white);
  border-color: var(--color-text);
}

.btn-lg { padding: 14px 30px; font-size: 1.05rem; }
.btn-sm { padding: 8px 16px; font-size: 0.875rem; }

.btn[aria-disabled="true"] {
  opacity: 0.6;
  pointer-events: none;
  cursor: not-allowed;
}

/* ==========================================================================
   Header
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  min-height: var(--header-height);
  transition: box-shadow 0.2s ease;
}
.site-header.is-scrolled { box-shadow: var(--shadow-sm); }

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--header-height);
  gap: 16px;
}

.logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
  flex-shrink: 0;
}
.logo span { color: var(--color-text); font-weight: 700; }

.main-nav { display: none; }
.main-nav ul { display: flex; gap: 28px; }
.main-nav a {
  font-weight: 500;
  color: var(--color-text);
  font-size: 0.95rem;
  transition: color 0.15s ease;
}
.main-nav a:hover,
.main-nav a.is-active { color: var(--color-primary); }

.header-actions { display: none; align-items: center; gap: 12px; }

.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
}
.hamburger span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.hamburger[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hamburger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-nav {
  display: none;
  flex-direction: column;
  gap: 20px;
  padding: 20px;
  border-top: 1px solid var(--color-border);
  background: var(--color-white);
}
.mobile-nav.is-open { display: flex; }
.mobile-nav ul { display: flex; flex-direction: column; gap: 4px; }
.mobile-nav a {
  display: block;
  padding: 10px 4px;
  font-weight: 500;
  font-size: 1rem;
}
.mobile-nav a:hover { color: var(--color-primary); }
.mobile-actions { display: flex; flex-direction: column; gap: 10px; }
.mobile-actions .btn { width: 100%; }

@media (min-width: 960px) {
  .main-nav { display: block; }
  .header-actions { display: flex; }
  .hamburger { display: none; }
  .mobile-nav { display: none !important; }
}

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  background: linear-gradient(180deg, #FFFFFF 0%, var(--color-primary-light) 100%);
  padding-block: 56px;
}

.hero-inner {
  display: flex;
  flex-direction: column;
  gap: 40px;
  align-items: center;
  text-align: center;
}

.hero-content h1 {
  font-size: clamp(2rem, 1.5rem + 2.2vw, 3.25rem);
  letter-spacing: -0.02em;
}

.hero-sub {
  margin-top: 18px;
  font-size: clamp(1rem, 0.95rem + 0.3vw, 1.15rem);
  color: var(--color-gray);
  max-width: 46ch;
  margin-inline: auto;
}

.hero-cta {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 28px;
}
.hero-cta .btn { width: 100%; }

.trust-badge {
  margin-top: 24px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.9rem;
  color: var(--color-gray);
  font-weight: 500;
}

.hero-visual {
  position: relative;
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}
.blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(0px);
}
.blob-1 {
  width: 70%;
  height: 70%;
  background: #EAE6D9;
  top: 5%;
  left: 10%;
}
.blob-2 {
  width: 45%;
  height: 45%;
  background: #DCD5C1;
  bottom: 0;
  right: 5%;
}
.hero-svg {
  position: relative;
  width: 65%;
  height: auto;
}

@media (min-width: 720px) {
  .hero-cta { flex-direction: row; justify-content: center; }
  .hero-cta .btn { width: auto; }
  .trust-badge { flex-direction: row; justify-content: center; gap: 20px; }
}

@media (min-width: 960px) {
  .hero-inner {
    flex-direction: row;
    text-align: left;
    gap: 60px;
  }
  .hero-content { flex: 1 1 50%; }
  .hero-sub { margin-inline: 0; }
  .hero-cta { justify-content: flex-start; }
  .trust-badge { justify-content: flex-start; }
  .hero-visual { flex: 1 1 40%; max-width: 380px; }
}

/* ==========================================================================
   Categories
   ========================================================================== */
.category-grid {
  display: grid;
  gap: 24px;
  grid-template-columns: 1fr;
}

.category-card {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  border: 1px solid var(--color-border);
  border-top: 4px solid var(--color-primary);
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.category-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.category-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  background: var(--color-primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.category-card h3 { font-size: 1.35rem; margin-bottom: 10px; }
.category-card p { color: var(--color-gray); margin-bottom: 20px; }

.link-arrow {
  color: var(--color-primary);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: gap 0.15s ease, color 0.15s ease;
}
.link-arrow:hover { gap: 10px; color: var(--color-primary-dark); }

.category-card .badge { margin-bottom: 14px; }

@media (min-width: 720px) {
  .category-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .category-grid--three { grid-template-columns: repeat(3, 1fr); }
}

/* ==========================================================================
   Inner page hero (category / listing pages)
   ========================================================================== */
.page-hero {
  background: var(--color-primary-light);
  padding-block: 40px 36px;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--color-gray);
  margin-bottom: 16px;
}
.breadcrumb a { color: var(--color-primary-dark); font-weight: 600; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb .sep { color: var(--color-gray); }

.page-hero h1 {
  font-size: clamp(1.75rem, 1.45rem + 1.3vw, 2.5rem);
  letter-spacing: -0.02em;
}
.page-hero p {
  margin-top: 10px;
  color: var(--color-gray);
  max-width: 60ch;
}

.search-bar { margin-top: 24px; max-width: 440px; }
.search-bar-inner {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 10px 18px;
}
.search-bar-inner svg { flex-shrink: 0; color: var(--color-gray); }
.search-bar-inner input {
  border: none;
  outline: none;
  background: transparent;
  flex: 1;
  min-width: 0;
  font: inherit;
  color: var(--color-text);
}
.search-bar-inner input::placeholder { color: var(--color-gray); }
.search-bar-inner:focus-within { border-color: var(--color-primary); }

.results-meta { margin-top: 14px; font-size: 0.88rem; color: var(--color-gray); }

.empty-state { display: none; text-align: center; padding: 48px 20px; color: var(--color-gray); }
.empty-state.is-visible { display: block; }

/* ==========================================================================
   How it works
   ========================================================================== */
.how-it-works { background: var(--color-primary-light); }

.steps {
  display: grid;
  gap: 32px;
  grid-template-columns: 1fr;
}

.step { text-align: center; }

.step-number {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-primary);
  color: var(--color-white);
  font-weight: 700;
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 16px;
}

.step h3 { font-size: 1.1rem; margin-bottom: 6px; }
.step p { color: var(--color-gray); font-size: 0.95rem; }

@media (min-width: 640px) {
  .steps { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .steps { grid-template-columns: repeat(4, 1fr); }
}

/* ==========================================================================
   Ebooks
   ========================================================================== */
.ebook-grid {
  display: grid;
  gap: 24px;
  grid-template-columns: 1fr;
}

.ebook-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.ebook-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.ebook-cover {
  background: var(--color-primary-light);
  aspect-ratio: 3 / 4;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

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

.ebook-body { padding: 20px; display: flex; flex-direction: column; gap: 10px; flex: 1; }

.badge {
  align-self: flex-start;
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  padding: 4px 10px;
  border-radius: 999px;
}

.ebook-body h3 { font-size: 1.05rem; }
.ebook-body p { color: var(--color-gray); font-size: 0.9rem; flex: 1; }

.ebook-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 8px;
}
.price { font-weight: 700; font-size: 1.1rem; }

.ebook-card:hover .btn-primary {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
}

@media (min-width: 640px) {
  .ebook-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .ebook-grid { grid-template-columns: repeat(4, 1fr); }
}

/* Library grid: 1 col mobile / 2 col tablet / 3 col desktop (editorial, more whitespace) */
@media (min-width: 1024px) {
  .ebook-grid--library { grid-template-columns: repeat(3, 1fr); }
}

.ebook-cover-link { display: block; }
.ebook-title-link { color: inherit; }
.ebook-title-link:hover h3 { color: var(--color-primary-dark); }

.ebook-tags {
  color: var(--color-gray);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.ebook-cover { position: relative; }
.coming-soon-badge {
  position: absolute;
  top: 12px;
  left: 12px;
  background: var(--color-white);
  color: var(--color-primary-dark);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  padding: 4px 10px;
  border-radius: 999px;
  box-shadow: var(--shadow-sm);
}

.price-muted { color: var(--color-gray); }

/* ==========================================================================
   Library controls (search + tag filter)
   ========================================================================== */
.library-controls {
  padding-block: 32px;
  border-bottom: 1px solid var(--color-border);
}

.search-bar--wide { max-width: 560px; margin-inline: auto; }

.tag-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-top: 20px;
}

.tag-chip {
  padding: 7px 16px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-white);
  color: var(--color-gray);
  font-size: 0.85rem;
  font-weight: 600;
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease;
}
.tag-chip:hover { border-color: var(--color-primary); color: var(--color-primary-dark); }
.tag-chip.is-active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
}

.library-controls .results-meta { text-align: center; }

/* ==========================================================================
   Ebook detail (stub) page
   ========================================================================== */
.detail-loading,
.detail-not-found { padding-block: 24px; color: var(--color-gray); }
.detail-not-found { display: flex; flex-direction: column; gap: 16px; align-items: flex-start; }

.detail-grid {
  display: flex;
  flex-direction: column;
  gap: 32px;
  padding-block: 8px 8px;
}

.detail-cover {
  flex: 0 0 auto;
  width: 100%;
  max-width: 280px;
  aspect-ratio: 3 / 4;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
}

.detail-info { display: flex; flex-direction: column; align-items: flex-start; gap: 12px; }
.detail-info h1 { font-size: clamp(1.6rem, 1.3rem + 1.2vw, 2.25rem); }
.detail-info p { color: var(--color-gray); }
.detail-info .ebook-tags { color: var(--color-gray); }

.price-lg { font-size: 1.5rem; font-weight: 700; color: var(--color-text); }

.detail-note { font-size: 0.85rem; color: var(--color-gray); margin-top: 4px; }

@media (min-width: 720px) {
  .detail-grid { flex-direction: row; align-items: flex-start; }
}

/* ==========================================================================
   Testimonials
   ========================================================================== */
.testimonials { background: var(--color-primary-light); }

.testimonial-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: 1fr;
}

.testimonial-card {
  background: var(--color-white);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.stars { color: var(--color-accent); letter-spacing: 2px; margin-bottom: 12px; }
.quote { font-size: 0.98rem; margin-bottom: 20px; }

.student { display: flex; align-items: center; gap: 12px; }
.avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-border);
  flex-shrink: 0;
}
.student-name { font-weight: 700; font-size: 0.92rem; }
.student-role { color: var(--color-gray); font-size: 0.85rem; }

@media (min-width: 640px) {
  .testimonial-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .testimonial-grid { grid-template-columns: repeat(4, 1fr); }
}

/* ==========================================================================
   Trust badges
   ========================================================================== */
.trust-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: 1fr;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.trust-item p { font-weight: 600; }

@media (min-width: 640px) {
  .trust-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ==========================================================================
   FAQ
   ========================================================================== */
.faq-list { display: flex; flex-direction: column; gap: 12px; }

.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  text-align: left;
  font-weight: 600;
  color: var(--color-text);
}
.faq-question:hover { color: var(--color-primary); }

.faq-icon {
  flex-shrink: 0;
  color: var(--color-primary);
  font-size: 1.25rem;
  font-weight: 400;
  transition: transform 0.2s ease;
}
.faq-question[aria-expanded="true"] .faq-icon { transform: rotate(45deg); }

.faq-answer {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.2s ease;
}
.faq-answer p {
  overflow: hidden;
  color: var(--color-gray);
  padding: 0 20px;
}
.faq-item.is-open .faq-answer { grid-template-rows: 1fr; }
.faq-item.is-open .faq-answer p { padding: 0 20px 18px; }

/* ==========================================================================
   Newsletter
   ========================================================================== */
.newsletter {
  background: var(--color-primary);
  padding-block: 64px;
  color: var(--color-white);
}
.newsletter-inner { text-align: center; }
.newsletter h2 {
  font-size: clamp(1.5rem, 1.3rem + 1vw, 2rem);
  color: var(--color-white);
}
.newsletter p { margin-top: 10px; color: rgba(255,255,255,0.9); }

.newsletter-form {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 440px;
  margin: 28px auto 0;
}
.newsletter-form input {
  width: 100%;
  padding: 12px 16px;
  border-radius: 999px;
  border: 2px solid transparent;
  font-size: 1rem;
  font-family: inherit;
}
.newsletter-form input:focus {
  outline: none;
  border-color: var(--color-text);
}
.newsletter-note { margin-top: 14px; font-size: 0.85rem; color: rgba(255,255,255,0.8); }

@media (min-width: 560px) {
  .newsletter-form { flex-direction: row; }
  .newsletter-form input { flex: 1; }
  .newsletter-form .btn { flex-shrink: 0; }
}

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  background: var(--color-footer-bg);
  color: #CBD5E1;
  padding-block: 56px 24px;
}

.footer-grid {
  display: grid;
  gap: 40px;
  grid-template-columns: 1fr;
}

.footer-brand p { margin-top: 14px; font-size: 0.92rem; max-width: 32ch; }
.logo-footer { color: var(--color-primary); }
.logo-footer span { color: var(--color-white); }

.social-links { display: flex; gap: 12px; margin-top: 20px; }
.social-links a {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(255,255,255,0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease, color 0.15s ease;
}
.social-links a:hover { background: var(--color-primary); color: var(--color-white); }

.footer-col h3 {
  color: var(--color-white);
  font-size: 0.95rem;
  margin-bottom: 16px;
}
.footer-col ul { display: flex; flex-direction: column; gap: 10px; }
.footer-col a { font-size: 0.92rem; transition: color 0.15s ease; }
.footer-col a:hover { color: var(--color-primary); }

.footer-bottom {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  text-align: center;
  font-size: 0.85rem;
}

@media (min-width: 640px) {
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .footer-grid { grid-template-columns: 2fr repeat(3, 1fr); }
}