/* Classroom Currents
   Layout: a single 72rem column of bands. The hero sits on drifting "current" lines;
   the gap section sets the textbook and the headline on either side of the bridge.
   Type: Bricolage Grotesque for display, Public Sans for reading, IBM Plex Mono for labels. */

/* One dark look on every device: dark navy ground, white type, teal outlines,
   and the brightest colors kept for what matters (buttons, key words, labels). */
:root {
  --paper: #0b1f44;        /* dark navy page, matched to the logo */
  --surface: #10294f;      /* raised navy for bands and cards */
  --ink: #ffffff;          /* white type */
  --muted: #b4c6d6;        /* softer text, still easy to read on navy */
  --line: rgba(64, 205, 214, 0.38);   /* teal outlines */
  --hair: rgba(64, 205, 214, 0.18);   /* quieter teal rules between bands */
  --teal: #40cdd6;         /* bright teal for buttons, links and key words */
  --teal-soft: rgba(64, 205, 214, 0.13);
  --on-teal: #06131f;      /* navy text on teal buttons */
  --gold: #f5b942;
  --gold-ink: #f5b942;     /* bright gold labels */
  --wave: rgba(64, 205, 214, 0.22);
  --glow: rgba(64, 205, 214, 0.28);
  --font-display: "Bricolage Grotesque", "Avenir Next", "Segoe UI", system-ui, sans-serif;
  --font-body: "Public Sans", "Helvetica Neue", Arial, system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, Menlo, Consolas, monospace;
  --radius: 12px;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.6;
}
h1, h2, h3, p, ul, ol { margin: 0; }
a { color: var(--teal); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
img, svg { max-width: 100%; }
:focus-visible { outline: 3px solid var(--gold); outline-offset: 3px; border-radius: 4px; }

.wrap {
  width: 100%;
  max-width: 74rem;
  margin-inline: auto;
  padding-left: max(20px, env(safe-area-inset-left, 0px));
  padding-right: max(20px, env(safe-area-inset-right, 0px));
}
.skip { position: absolute; left: -999px; top: 8px; background: var(--surface); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 12px; }

/* ---------- header ---------- */
.site-header { background: var(--paper); border-bottom: 1px solid var(--hair); }
.header-row {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 0.75rem 1.5rem; padding-block: 0.9rem;
}
.brand { display: inline-flex; align-items: center; gap: 0.65rem; color: var(--ink); text-decoration: none; }
.brand-logo { width: 44px; height: 44px; flex: none; display: block; }
.brand-name { font-family: var(--font-display); font-weight: 750; font-size: 1.3rem; letter-spacing: -0.015em; }
.nav { display: flex; flex-wrap: wrap; align-items: center; gap: 0.25rem; }
.nav a {
  padding: 0.45rem 0.75rem; border-radius: 8px; color: var(--muted);
  font-weight: 600; font-size: 0.95rem; text-decoration: none;
}
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); background: var(--teal-soft); }
.nav .btn { margin-left: 0.4rem; }
@media (max-width: 600px) {
  .nav { gap: 0.1rem; margin-left: -0.6rem; }
  .nav a { padding: 0.4rem 0.6rem; font-size: 0.92rem; }
  .nav .btn { display: none; }
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 0.45rem;
  padding: 0.7rem 1.15rem; border-radius: 10px; border: 1.5px solid var(--teal);
  font-weight: 650; font-size: 0.98rem; line-height: 1.2; text-decoration: none;
  color: var(--teal); background: transparent;
}
.btn:hover { background: var(--teal-soft); }
.btn-solid { background: var(--teal); color: var(--on-teal); }
.btn-solid:hover { background: var(--teal); filter: brightness(1.08); }
.nav .btn { padding: 0.5rem 0.9rem; font-size: 0.9rem; color: var(--on-teal); background: var(--teal); }
.btn-row { display: flex; flex-wrap: wrap; gap: 0.75rem; }

/* ---------- type helpers ---------- */
.eyebrow {
  font-family: var(--font-mono); font-size: 0.78rem; font-weight: 500;
  letter-spacing: 0.09em; text-transform: uppercase; color: var(--gold-ink);
}
.h-display {
  font-family: var(--font-display); font-weight: 800; letter-spacing: -0.025em;
  font-size: clamp(2.6rem, 6.4vw, 4.6rem); line-height: 1; text-wrap: balance;
}
.h-section {
  font-family: var(--font-display); font-weight: 750; letter-spacing: -0.018em;
  font-size: clamp(1.7rem, 3.4vw, 2.4rem); line-height: 1.1; text-wrap: balance;
}
.lead { font-size: clamp(1.1rem, 1.8vw, 1.3rem); color: var(--muted); max-width: 40rem; }
.muted { color: var(--muted); }

/* ---------- bands ---------- */
.band { padding-block: clamp(3rem, 7vw, 5.5rem); }
.band-surface { background: var(--surface); border-block: 1px solid var(--hair); }
.band-head { display: grid; gap: 0.7rem; max-width: 46rem; margin-bottom: 2.25rem; }

/* ---------- hero ---------- */
.hero { position: relative; overflow: hidden; border-bottom: 1px solid var(--hair); background: radial-gradient(120% 90% at 85% 10%, rgba(64, 205, 214, 0.10), transparent 60%), var(--paper); }
.hero-waves { position: absolute; inset: auto 0 0 0; height: 46%; max-width: none; pointer-events: none; }
.hero-waves path { fill: none; stroke: var(--wave); stroke-width: 2; vector-effect: non-scaling-stroke; }
.hero-waves .drift { animation: drift 18s linear infinite; }
.hero-waves .drift-slow { animation: drift 28s linear infinite reverse; }
@keyframes drift { from { transform: translateX(0); } to { transform: translateX(-400px); } }
.hero-inner {
  position: relative; display: grid; gap: 1.4rem; justify-items: start;
  padding-block: clamp(3.5rem, 9vw, 7rem) clamp(3rem, 8vw, 6rem);
}
.hero .h-display { max-width: 15ch; }
.hero-grid { position: relative; display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 0.8fr); align-items: center; gap: 2rem; }
.hero-globe { width: 100%; max-width: 440px; height: auto; justify-self: end; filter: drop-shadow(0 24px 48px rgba(0, 0, 0, 0.35)); }
@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: 0; }
  .hero-globe { display: none; }
}
.hero .h-display em { font-style: normal; color: var(--teal); }

/* ---------- the gap ---------- */
.gap-grid {
  display: grid; grid-template-columns: minmax(0, 1fr) auto minmax(0, 1.25fr) auto minmax(0, 1fr);
  align-items: stretch; gap: 0.75rem;
}
.gap-card {
  display: grid; align-content: start; gap: 0.9rem; padding: 1.5rem;
  background: var(--paper); border: 1px solid var(--line); border-radius: var(--radius);
}
.gap-card h3 { font-family: var(--font-display); font-weight: 700; font-size: 1.35rem; line-height: 1.2; }
.gap-card .label { font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.gap-card dl { display: grid; gap: 0.75rem; margin: 0; }
.gap-card dt { font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.gap-card dd { margin: 0.15rem 0 0; }
.gap-card.bridge { background: var(--surface); border: 2px solid var(--teal); box-shadow: 0 0 0 4px var(--teal-soft), 0 18px 40px -20px var(--glow); }
.gap-card.bridge .label { color: var(--teal); }
.gap-card.bridge ul { padding-left: 1.1rem; display: grid; gap: 0.55rem; }
.gap-arrow { align-self: center; display: grid; justify-items: center; gap: 0.3rem; color: var(--teal); }
.gap-arrow span { font-family: var(--font-mono); font-size: 0.7rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); writing-mode: horizontal-tb; text-align: center; max-width: 6.5rem; }
.gap-arrow svg { width: 34px; height: 18px; }
.gap-note { margin-top: 1.75rem; max-width: 46rem; }
@media (max-width: 920px) {
  .gap-grid { grid-template-columns: 1fr; }
  .gap-grid .curriculum { order: 1; }
  .gap-grid .news { order: 2; }
  .gap-grid .bridge { order: 3; margin-top: 0.75rem; }
  .gap-arrow { display: none; }
}

/* ---------- steps ---------- */
.steps { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 1.5rem; counter-reset: step; }
.steps li { display: grid; align-content: start; gap: 0.4rem; padding-top: 1rem; border-top: 2px solid var(--teal); }
.steps .num { font-family: var(--font-mono); font-size: 0.8rem; color: var(--gold-ink); }
.steps h3 { font-family: var(--font-display); font-weight: 700; font-size: 1.15rem; }
.steps p { color: var(--muted); font-size: 0.98rem; }
@media (max-width: 1000px) { .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 560px) { .steps { grid-template-columns: 1fr; } }

/* ---------- unit chips ---------- */
.units { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr)); gap: 0.6rem; }
.units a {
  display: flex; align-items: baseline; gap: 0.7rem; padding: 0.8rem 1rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: 10px;
  color: var(--ink); text-decoration: none; font-weight: 600; line-height: 1.3;
}
.units a:hover { border-color: var(--teal); }
.units .n { font-family: var(--font-mono); font-size: 0.8rem; color: var(--teal); font-weight: 500; }

/* ---------- topic / lesson cards ---------- */
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(17rem, 1fr)); gap: 1rem; }
.card {
  display: grid; align-content: start; gap: 0.7rem; padding: 1.35rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
}
a.card { color: var(--ink); text-decoration: none; }
a.card:hover { border-color: var(--teal); box-shadow: 0 0 0 3px var(--teal-soft); }
.card h3 { font-family: var(--font-display); font-weight: 700; font-size: 1.22rem; line-height: 1.2; }
.card p { color: var(--muted); font-size: 0.98rem; }
.tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.tag {
  font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.03em;
  padding: 0.2rem 0.55rem; border-radius: 999px; background: var(--teal-soft); color: var(--teal);
}
.tag.soon { background: transparent; border: 1px dashed var(--line); color: var(--muted); }
.card .more { font-weight: 650; font-size: 0.95rem; color: var(--teal); }

/* ---------- topic sections (current events page) ---------- */
.topic { display: grid; grid-template-columns: minmax(0, 18rem) minmax(0, 1fr); gap: 1.5rem 3rem; padding-block: 2.5rem; border-top: 1px solid var(--hair); }
.topic:first-of-type { border-top: 0; padding-top: 0; }
.topic-head { display: grid; align-content: start; gap: 0.6rem; }
.topic-head h2 { font-family: var(--font-display); font-weight: 750; font-size: 1.6rem; line-height: 1.15; }
.lesson-list { display: grid; gap: 0.9rem; }
.lesson {
  display: grid; gap: 0.5rem; padding: 1.2rem 1.35rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
}
.lesson h3 { font-family: var(--font-display); font-weight: 700; font-size: 1.18rem; line-height: 1.25; }
.lesson .meta { font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.05em; text-transform: uppercase; color: var(--muted); }
.lesson p { color: var(--muted); }
.lesson-foot { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 0.6rem 1rem; }
@media (max-width: 820px) { .topic { grid-template-columns: 1fr; } }

.soon-list { list-style: none; padding: 0; display: flex; flex-wrap: wrap; gap: 0.6rem; }
.soon-list li { padding: 0.55rem 0.95rem; border: 1px dashed var(--line); border-radius: 999px; font-weight: 600; color: var(--muted); background: var(--surface); }

/* ---------- AP units page ---------- */
.unit { display: grid; grid-template-columns: 5.5rem minmax(0, 1fr); gap: 1rem 1.75rem; padding-block: 2.25rem; border-top: 1px solid var(--line); }
.unit:first-of-type { border-top: 0; padding-top: 0; }
.unit-num { font-family: var(--font-display); font-weight: 800; font-size: 3.4rem; line-height: 0.9; color: var(--teal); }
.unit-body { display: grid; gap: 0.9rem; }
.unit-body h2 { font-family: var(--font-display); font-weight: 750; font-size: 1.45rem; line-height: 1.2; }
.unit-cols { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem 2rem; }
.unit-cols h3 { font-family: var(--font-mono); font-size: 0.74rem; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 0.35rem; }
.unit-cols ul { padding-left: 1.1rem; display: grid; gap: 0.3rem; }
@media (max-width: 760px) {
  .unit { grid-template-columns: 1fr; }
  .unit-num { font-size: 2.4rem; }
  .unit-cols { grid-template-columns: 1fr; }
}

/* ---------- callout band ---------- */
.callout { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 1.5rem 3rem; }
.callout .h-section { max-width: 22ch; }
@media (max-width: 760px) { .callout { grid-template-columns: 1fr; } }

/* ---------- prose pages ---------- */
.prose { display: grid; gap: 1.1rem; max-width: 44rem; }
.prose h2 { font-family: var(--font-display); font-weight: 750; font-size: 1.6rem; line-height: 1.2; margin-top: 1.25rem; }
.prose ul { padding-left: 1.2rem; display: grid; gap: 0.5rem; }
.principles { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; max-width: 52rem; }
.principles div { padding: 1.2rem 1.3rem; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); display: grid; gap: 0.35rem; }
.principles h3 { font-family: var(--font-display); font-weight: 700; font-size: 1.12rem; }
.principles p { color: var(--muted); font-size: 0.98rem; }
@media (max-width: 640px) { .principles { grid-template-columns: 1fr; } }

/* ---------- page head ---------- */
.page-head { border-bottom: 1px solid var(--hair); background: radial-gradient(120% 120% at 90% 0%, rgba(64, 205, 214, 0.10), transparent 60%), var(--paper); }
.page-head .wrap { display: grid; gap: 0.9rem; padding-block: clamp(2.5rem, 6vw, 4.25rem); }

/* ---------- footer ---------- */
.site-footer { background: var(--paper); border-top: 1px solid var(--hair); }
.footer-row { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 1.5rem 3rem; padding-block: 2.5rem; align-items: start; }
.footer-row p { color: var(--muted); font-size: 0.95rem; max-width: 36rem; }
.footer-nav { display: flex; flex-wrap: wrap; gap: 0.4rem 1.2rem; }
.footer-nav a { color: var(--muted); font-weight: 600; font-size: 0.95rem; text-decoration: none; }
.footer-nav a:hover { color: var(--ink); }
@media (max-width: 700px) { .footer-row { grid-template-columns: 1fr; } }

@media (prefers-reduced-motion: reduce) {
  .hero-waves .drift, .hero-waves .drift-slow { animation: none; }
}