/* ============================================================
   BLOS ELEMENTARY FOUNDATIONS | MATHEMATICS K–5
   STYLESHEET ORGANIZATION
   01. Design tokens and global resets
   02. Shared layout and navigation
   03. Hero and featured book covers
   04. Series statistics and book catalog
   05. Features, teaching method, and audiences
   06. FAQ, footer, and modal
   07. Responsive breakpoints
   ============================================================ */
:root {
  --navy:#0a2348;
  --navy2:#06172e;
  --gold:#f5ba3e;
  --cream:#fff9ee;
  --ink:#172843;
  --muted:#66758a;
  --line:#e5e8ef;
  --blue:#1a74bd;
  --green:#087f59;
  --violet:#7042bd;
  --shadow:0 20px 55px rgba(8,30,59,.12)
}

* {
  box-sizing:border-box
}

html {
  scroll-behavior:smooth
}

body {
  margin:0;
  color:var(--ink);
  background:#fff;
  font-family:Inter,ui-sans-serif,system-ui,-apple-system,Segoe UI,Arial,sans-serif
}

button,a {
  font:inherit
}

a {
  color:inherit;
  text-decoration:none
}

button {
  cursor:pointer
}

img {
  display:block;
  max-width:100%
}

.container {
  max-width:1200px;
  margin:auto;
  padding:0 26px
}

.eyebrow {
  font-size:.73rem;
  letter-spacing:.2em;
  font-weight:800;
  text-transform:uppercase;
  color:#a86a0a
}

.serif {
  font-family:Georgia,Cambria,'Times New Roman',serif
}

.nav {
  position:sticky;
  top:0;
  z-index:30;
  background:rgba(255,255,255,.94);
  backdrop-filter:blur(16px);
  border-bottom:1px solid #edf0f3
}

.nav-inner {
  height:78px;
  display:flex;
  align-items:center;
  gap:30px;
  justify-content:space-between
}

.brand {
  display:flex;
  align-items:center;
  gap:12px;
  min-width:0
}

.brand-mark {
  background:var(--navy);
  color:var(--gold);
  border:2px solid var(--gold);
  height:44px;
  width:54px;
  border-radius:12px;
  display:grid;
  place-items:center;
  font-family:Georgia,serif;
  font-weight:800;
  font-size:1.3rem
}

.brand-text {
  line-height:1.1
}

.brand-text strong {
  display:block;
  font-size:.89rem;
  letter-spacing:.1em;
  color:var(--navy)
}

.brand-text span {
  font-size:.67rem;
  letter-spacing:.07em;
  color:var(--muted)
}

.nav-links {
  display:flex;
  gap:26px;
  align-items:center;
  font-size:.88rem;
  font-weight:700;
  color:#33445e
}

.nav-links a:hover {
  color:var(--blue)
}

.btn {
  border:0;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:10px;
  padding:14px 22px;
  border-radius:12px;
  font-weight:800;
  font-size:.91rem;
  transition:transform .2s,box-shadow .2s
}

.btn:hover {
  transform:translateY(-2px)
}

.btn-primary {
  background:var(--gold);
  color:var(--navy);
  box-shadow:0 8px 20px rgba(245,186,62,.22)
}

.btn-outline {
  background:#fff;
  border:1px solid #cbd5e2;
  color:var(--navy)
}

.btn-dark {
  background:var(--navy);
  color:white
}

.hero {
  background:radial-gradient(ellipse at 82% 20%,#194e85 0,transparent 44%),linear-gradient(130deg,#06152f 0%,#0b2b54 56%,#16436d 100%);
  color:#fff;
  overflow:hidden;
  position:relative
}

.hero:before {
  content:"";
  position:absolute;
  right:-120px;
  top:80px;
  width:500px;
  height:500px;
  border-radius:50%;
  border:1px solid #ffffff24;
  box-shadow:0 0 0 85px #ffffff08,0 0 0 180px #ffffff06
}

.hero-inner {
  padding-top:87px;
  padding-bottom:79px;
  display:grid;
  grid-template-columns:44% 56%;
  align-items:center;
  gap:0;
  position:relative
}

.hero-copy {
  position:relative;
  z-index:2
}

.hero .eyebrow {
  color:#ffd57e
}

.hero h1 {
  font-size:clamp(2.9rem,5vw,5.3rem);
  letter-spacing:-.045em;
  line-height:1.04;
  margin:19px 0
}

.hero h1 em {
  color:#ffd36e;
  font-style:normal
}

.hero p {
  font-size:1.07rem;
  color:#d9e7f6;
  line-height:1.8;
  max-width:490px;
  margin-bottom:27px
}

.hero-actions {
  display:flex;
  gap:12px;
  flex-wrap:wrap
}

.hero .btn-outline {
  background:#ffffff10;
  border-color:#ffffff55;
  color:#fff
}

.small-proof {
  margin-top:31px;
  display:flex;
  gap:18px;
  align-items:center;
  color:#d9e5f0;
  font-size:.77rem;
  font-weight:650
}

.small-proof span+span:before {
  content:'•';
  padding-right:17px;
  color:#eab85b
}

.book-fan {
  height:545px;
  position:relative;
  display:flex;
  align-items:flex-end;
  justify-content:center;
  perspective:1200px;
  padding:0 5px 15px 18px
}

.book-fan img {
  height:405px;
  width:auto;
  object-fit:contain;
  position:absolute;
  bottom:22px;
  filter:drop-shadow(0 26px 20px rgba(0,0,0,.4));
  border-radius:4px;
  transition:transform .35s
}

.book-fan img:nth-child(1) {
  left:1%;
  transform:rotate(-14deg) translateY(12px);
  z-index:1
}

.book-fan img:nth-child(2) {
  left:16%;
  transform:rotate(-8deg) translateY(-6px);
  z-index:2
}

.book-fan img:nth-child(3) {
  left:34%;
  transform:translateY(-25px);
  z-index:5
}

.book-fan img:nth-child(4) {
  left:51%;
  transform:rotate(7deg) translateY(-7px);
  z-index:3
}

.book-fan img:nth-child(5) {
  left:66%;
  transform:rotate(13deg) translateY(15px);
  z-index:2
}

.book-fan:hover img:nth-child(3) {
  transform:translateY(-36px)
}

.strip {
  border-bottom:1px solid var(--line);
  background:#fff
}

.strip-grid {
  display:grid;
  grid-template-columns:repeat(4,1fr)
}

.strip-grid div {
  padding:24px 10px;
  text-align:center;
  border-right:1px solid var(--line)
}

.strip-grid div:last-child {
  border:0
}

.strip-grid b {
  display:block;
  color:var(--navy);
  font-size:1rem
}

.strip-grid span {
  font-size:.79rem;
  color:var(--muted)
}

.section {
  padding:94px 0
}

.section-head {
  text-align:center;
  max-width:760px;
  margin:0 auto 40px
}

.section-head h2 {
  font-family:Georgia,serif;
  font-size:clamp(2rem,3vw,3.1rem);
  line-height:1.2;
  margin:12px 0 14px;
  color:var(--navy)
}

.section-head p {
  color:var(--muted);
  line-height:1.75;
  margin:0
}

.selector {
  display:flex;
  gap:10px;
  flex-wrap:wrap;
  justify-content:center;
  margin-bottom:35px
}

.chip {
  border:1px solid #d7dfe9;
  background:#fff;
  padding:11px 21px;
  border-radius:100px;
  color:#3b516e;
  font-weight:750
}

.chip.active {
  background:var(--navy);
  color:white;
  border-color:var(--navy)
}

.cards {
  display:grid;
  grid-template-columns:repeat(5,minmax(0,1fr));
  gap:17px
}

.book-card {
  border:1px solid #e5e9ef;
  border-radius:17px;
  background:#fff;
  overflow:hidden;
  box-shadow:0 8px 32px rgba(15,44,80,.05);
  display:flex;
  flex-direction:column;
  transition:transform .2s,box-shadow .2s
}

.book-card:hover {
  transform:translateY(-5px);
  box-shadow:var(--shadow)
}

.card-cover {
  background:linear-gradient(145deg,#eef3f7,#fff8ea);
  padding:19px 19px 10px;
  display:grid;
  place-items:center;
  aspect-ratio:4/5
}

.card-cover img {
  height:100%;
  max-height:290px;
  object-fit:contain;
  filter:drop-shadow(0 13px 12px #0c2a4538)
}

.card-content {
  padding:17px 16px 20px;
  display:flex;
  flex-direction:column;
  flex:1
}

.grade {
  font-size:.66rem;
  letter-spacing:.13em;
  font-weight:850;
  text-transform:uppercase;
  color:var(--blue)
}

.card-content h3 {
  font-family:Georgia,serif;
  font-size:1.13rem;
  line-height:1.3;
  margin:8px 0;
  color:var(--navy)
}

.card-content p {
  color:var(--muted);
  font-size:.82rem;
  line-height:1.65;
  margin:0 0 17px;
  flex:1
}

.text-button {
  padding:0;
  border:0;
  background:none;
  display:inline;
  text-align:left;
  color:#0c65a6;
  font-weight:800;
  font-size:.86rem
}

.text-button:hover {
  text-decoration:underline
}

.feature-section {
  background:#f7f9fc
}

.features {
  display:grid;
  grid-template-columns:repeat(3,1fr);
  gap:18px
}

.feature {
  background:white;
  border:1px solid #edf0f4;
  border-radius:16px;
  padding:28px
}

.feature-icon {
  width:49px;
  height:49px;
  background:#f8edcf;
  border-radius:13px;
  display:grid;
  place-items:center;
  font-size:1.5rem;
  margin-bottom:17px
}

.feature h3 {
  color:var(--navy);
  margin:0 0 8px;
  font-size:1.05rem
}

.feature p {
  font-size:.88rem;
  line-height:1.7;
  color:var(--muted);
  margin:0
}

.method {
  background:var(--cream);
  padding:93px 0
}

.method-grid {
  display:grid;
  grid-template-columns:38% 62%;
  align-items:center;
  gap:44px
}

.method h2 {
  font-size:2.7rem;
  line-height:1.15;
  margin:11px 0 18px;
  color:var(--navy)
}

.method p {
  color:#5c6779;
  line-height:1.85
}

.steps {
  display:grid;
  grid-template-columns:repeat(2,1fr);
  gap:14px
}

.step {
  background:white;
  border:1px solid #f2e4c9;
  border-radius:15px;
  padding:21px;
  min-height:148px
}

.step b {
  color:var(--blue);
  font-size:.72rem;
  letter-spacing:.12em
}

.step h3 {
  margin:10px 0 6px;
  color:var(--navy)
}

.step p {
  font-size:.84rem;
  margin:0
}

.pathways {
  display:grid;
  grid-template-columns:repeat(2,1fr);
  gap:20px
}

.path {
  border-radius:20px;
  border:1px solid var(--line);
  padding:34px;
  background:#fff
}

.path:nth-child(2) {
  background:#0d2a51;
  color:#fff;
  border:0
}

.path h3 {
  font-family:Georgia,serif;
  font-size:1.75rem;
  margin:10px 0
}

.path p {
  line-height:1.75;
  font-size:.91rem;
  color:var(--muted)
}

.path:nth-child(2) p {
  color:#d6e3ef
}

.path .btn {
  margin-top:9px
}

.path:nth-child(2) .btn {
  background:var(--gold);
  color:var(--navy)
}

.faq {
  max-width:840px;
  margin:auto
}

.faq details {
  border-bottom:1px solid var(--line);
  padding:19px 4px
}

.faq summary {
  cursor:pointer;
  font-weight:800;
  color:var(--navy);
  list-style:none
}

.faq summary:after {
  content:'+';
  float:right;
  font-size:1.3rem
}

.faq details[open] summary:after {
  content:'−'
}

.faq p {
  color:var(--muted);
  line-height:1.7;
  font-size:.91rem
}

.footer {
  background:var(--navy2);
  color:#dae6f2;
  padding:38px 0
}

.footer-row {
  display:flex;
  justify-content:space-between;
  gap:20px;
  align-items:center
}

.footer b {
  color:#fff
}

.footer small {
  color:#a9bacd
}

.modal {
  position:fixed;
  inset:0;
  background:#001329bb;
  z-index:80;
  display:none;
  align-items:center;
  justify-content:center;
  padding:25px
}

.modal[aria-hidden=false] {
  display:flex
}

.dialog {
  background:white;
  border-radius:22px;
  padding:30px;
  max-width:770px;
  width:100%;
  display:grid;
  grid-template-columns:210px 1fr;
  gap:32px;
  position:relative;
  max-height:90vh;
  overflow:auto
}

.dialog img {
  width:100%;
  border-radius:8px;
  box-shadow:0 14px 25px #0002
}

.dialog h2 {
  font-family:Georgia,serif;
  color:var(--navy);
  font-size:2rem;
  margin:12px 0
}

.dialog p {
  line-height:1.7;
  color:var(--muted)
}

.dialog ul {
  padding-left:19px;
  line-height:1.85;
  color:#36465b
}

.close {
  position:absolute;
  top:12px;
  right:14px;
  border:0;
  background:#edf1f6;
  height:35px;
  width:35px;
  border-radius:50%;
  font-size:1.35rem
}

.notice {
  padding:13px 16px;
  border-radius:10px;
  background:#f0f5fa;
  font-size:.82rem;
  color:#455772;
  margin-top:19px
}

.footer a {
  text-decoration:underline
}

.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
}

@media(max-width:1050px) {
  .hero-inner {
    grid-template-columns:1fr
  }

  .hero-copy {
    text-align:center
  }

  .hero-copy p {
    margin-left:auto;
    margin-right:auto
  }

  .hero-actions,.small-proof {
    justify-content:center
  }

  .book-fan {
    height:460px
  }

  .book-fan img {
    height:345px
  }

  .cards {
    grid-template-columns:repeat(3,1fr)
  }

  .nav-links {
    gap:14px
  }

  .method-grid {
    grid-template-columns:1fr
  }

  .method h2 {
    font-size:2.3rem
  }

}

@media(max-width:680px) {
  .container {
    padding:0 18px
  }

  .nav-inner {
    height:65px
  }

  .nav-links {
    display:none
  }

  .brand-text strong {
    font-size:.72rem
  }

  .brand-text span {
    font-size:.57rem
  }

  .brand-mark {
    height:38px;
    width:43px
  }

  .hero-inner {
    padding:55px 0 25px
  }

  .hero h1 {
    font-size:3rem
  }

  .hero p {
    font-size:.96rem
  }

  .small-proof {
    gap:8px;
    flex-wrap:wrap
  }

  .small-proof span+span:before {
    padding-right:6px
  }

  .book-fan {
    height:300px;
    margin-top:25px
  }

  .book-fan img {
    height:224px
  }

  .book-fan img:nth-child(1) {
    left:0
  }

  .book-fan img:nth-child(2) {
    left:16%
  }

  .book-fan img:nth-child(3) {
    left:30%
  }

  .book-fan img:nth-child(4) {
    left:48%
  }

  .book-fan img:nth-child(5) {
    left:64%
  }

  .strip-grid {
    grid-template-columns:repeat(2,1fr)
  }

  .strip-grid div:nth-child(2) {
    border:0
  }

  .strip-grid div:nth-child(-n+2) {
    border-bottom:1px solid var(--line)
  }

  .section {
    padding:67px 0
  }

  .cards {
    grid-template-columns:repeat(2,1fr);
    gap:11px
  }

  .card-cover {
    padding:9px;
    aspect-ratio:3/4
  }

  .card-content {
    padding:13px 11px
  }

  .card-content h3 {
    font-size:1rem
  }

  .features,.pathways,.steps {
    grid-template-columns:1fr
  }

  .method {
    padding:70px 0
  }

  .dialog {
    grid-template-columns:1fr;
    max-width:390px;
    padding:18px
  }

  .dialog img {
    max-width:160px;
    margin:auto
  }

  .footer-row {
    flex-direction:column;
    text-align:center
  }

  .section-head h2 {
    font-size:2.05rem
  }

}

@media(max-width:380px) {
  .cards {
    grid-template-columns:1fr
  }

  .card-cover {
    aspect-ratio:4/4
  }

  .card-cover img {
    max-height:280px
  }

}

/* Keep all four BLOS letters comfortably within the mark on every screen. */
.brand-mark {
  flex: 0 0 60px;
  min-width: 60px;
  width: 60px;
  white-space: nowrap;
  font-size: 1.25rem;
  line-height: 1;
  letter-spacing: -.035em;
}
@media (max-width: 680px) {
  .brand-mark { flex-basis: 52px; min-width: 52px; width: 52px; font-size: 1.1rem; }
}