/* Course identity and shared interface components. Maths topic colours stay local. */
:root, [data-course="site"], [data-course="revision"], [data-course="gcse"] {
  --course-accent: #2563eb;
  --course-button: #2563eb;
  --course-button-ink: #fff;
  --course-button-hover: #1d4ed8;
  --course-strong: #1d4ed8;
  --course-pale: #eff6ff;
  --course-wash: #dbeafe;
  --course-line: #bfdbfe;
  --course-ring: #93c5fd;
}
[data-course="a-level"] {
  --course-accent: #7c3aed;
  --course-button: #7c3aed;
  --course-button-ink: #fff;
  --course-button-hover: #6d28d9;
  --course-strong: #6d28d9;
  --course-pale: #f5f3ff;
  --course-wash: #ede9fe;
  --course-line: #ddd6fe;
  --course-ring: #c4b5fd;
}
[data-course="ib"] {
  --course-accent: #f97316;
  --course-button: #f97316;
  --course-button-ink: #fff;
  --course-button-hover: #ef650e;
  --course-strong: #9a3412;
  --course-pale: #fff7ed;
  --course-wash: #ffedd5;
  --course-line: #fed7aa;
  --course-ring: #fdba74;
}
[data-course="ap"] {
  --course-accent: #eab308;
  --course-button: #facc15;
  --course-button-ink: #fff;
  --course-button-hover: #eab308;
  --course-strong: #854d0e;
  --course-pale: #fefce8;
  --course-wash: #fef9c3;
  --course-line: #fde047;
  --course-ring: #facc15;
}

/* A steady font weight prevents the navigation moving when a section is active. */
header .nav-links > .dropdown > .dropbtn {
  font-family: Arial, Helvetica, sans-serif;
  font-size: .98rem;
  font-weight: 700;
  color: #374151;
  padding: 10px 14px;
  border-radius: 10px;
}
header .nav-links > .dropdown > .dropbtn:is(:hover, :focus-visible, [aria-current]) {
  color: var(--course-strong);
  background: var(--course-pale);
}
header .dropdown-content a:hover {
  color: var(--course-strong);
  background: var(--course-pale);
}
header .dropdown-content a[aria-current="page"] {
  color: var(--course-strong);
  background: var(--course-pale);
  font-weight: 700;
}
header .dropdown.nav-open > .dropdown-content { display: block; }
header .dropdown.nav-closed > .dropdown-content { display: none; }
@media (max-width: 950px) {
  header .navbar { overflow: visible; }
  header .nav-links {
    position: absolute; top: 100%; right: 0; left: auto;
    box-sizing: border-box; width: min(320px, 100%); max-width: 100%;
    max-height: calc(100dvh - 110px); overflow-y: auto;
    display: none; flex-direction: column; align-items: stretch; gap: 4px;
    padding: 10px; margin: 0; border: 1px solid #e5e7eb; border-radius: 16px;
    background: #fff; box-shadow: 0 10px 28px #0f172a24; z-index: 1001;
  }
  header .nav-links.active { display: flex; }
  header .nav-links > .dropdown { display: block; width: 100%; }
  header .nav-links > .dropdown > .dropbtn,
  header .nav-links > a {
    display: block; box-sizing: border-box; width: 100%; min-height: 44px;
    padding: 10px 14px; text-align: left;
  }
  header .nav-links .dropdown > .dropdown-content { display: none; }
}

/* Shared course/pathway buttons match the original Foundation / Core button. */
body .btn, body .course-choice .btn {
  display: inline-block;
  max-width: 100%;
  padding: 12px 22px;
  border-radius: 14px;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.6;
  text-align: center;
  text-decoration: none;
  transition: background-color .2s, color .2s;
}
body .btn-primary { border: 0; background: var(--course-button); color: var(--course-button-ink); }
body .btn-primary:hover { background: var(--course-button-hover); color: var(--course-button-ink); text-decoration: none; }
body .btn-secondary { border: 1px solid var(--course-line); background: #fff; color: var(--course-strong); }
body .btn-secondary:hover { background: var(--course-pale); color: var(--course-strong); }
body .btn-disabled { background: #e5e7eb; color: #64748b; cursor: default; }
body :is(a, button, input, summary):focus-visible { outline-color: var(--course-button); }

/* The course colour frames the page; each skill retains its teaching palette. */
body :is(.hero-card, .revision-course) {
  background: linear-gradient(135deg, #fff 0%, var(--course-pale) 100%);
  border-color: var(--course-line);
}
body :is(.card, .topic-card, .resource-block, .feature-box, .coming-soon-card, .course-choice, .subject-card) {
  border-radius: 22px;
  border: 1.5px solid var(--course-accent);
}
body :is(.card, .topic-card, .resource-block, .feature-box, .course-choice):not([aria-disabled="true"]):hover {
  border-color: var(--course-accent);
}
body #pathways .card { display: flex; flex-direction: column; }
body #pathways .quick-links { margin-top: auto; }
body :is(.card, .topic-card).coming-soon { border-color: var(--course-accent); }
body .course-choice { background: #fff; padding: 26px; gap: 12px; }
body .course-choice .btn { margin-top: auto; }
body .course-choice-icon { color: var(--course-accent); }
body .course-choice h2 { color: #111827; font-size: 1.35rem; }
body .course-choice p { color: #6b7280; font-size: .97rem; }
body .course-choices { gap: 22px; }
body .revision-course > .directory-shell { border-color: var(--course-line); }
body .revision-course .course-back { color: var(--course-strong); }
body .course-back a:hover { color: var(--course-strong); }
body .availability button[aria-pressed="true"] { background: var(--course-button); color: var(--course-button-ink); }
body .availability-tip { border-color: var(--course-accent); }
body .availability-tip::after { border-color: var(--course-accent); }
body .empty-state { border-color: var(--course-line); }

/* Unavailable courses and skills use the same stamp as GCSE practice papers. */
body .availability-pending[aria-disabled="true"],
body .skill-tile[data-status="coming-soon"] {
  position: relative;
  background: #f1f3f5;
  border-color: #cbd5e1;
  box-shadow: none;
}
body .availability-pending:hover { background: #f1f3f5; border-color: #cbd5e1; box-shadow: none; }
body .card.availability-pending :is(h3, p, .feature-list li) { color: #475569; }
.availability-pending-content {
  display: flex;
  flex-direction: column;
  align-items: inherit;
  flex: 1;
  gap: inherit;
  width: 100%;
  min-width: 0;
  filter: grayscale(1);
  opacity: .42;
}
.availability-pending .btn:disabled { cursor: default; }
.coming-soon-stamp,
.skill-tile[data-status="coming-soon"] .soon-label {
  position: absolute;
  z-index: 2;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%) rotate(-8deg);
  pointer-events: none;
  box-sizing: border-box;
  width: max-content;
  max-width: calc(100% - 26px);
  padding: 10px 14px;
  border: 3px solid #1d4ed8;
  border-radius: 8px;
  background: #ffffffed;
  color: #1d4ed8;
  box-shadow: 0 4px 16px #0f172a16;
  font: 800 clamp(.9rem, 1.5vw, 1.08rem)/1.25 Arial, Helvetica, sans-serif;
  text-transform: uppercase;
  letter-spacing: .08em;
  white-space: nowrap;
}
body .skill-tile[data-status="coming-soon"] { min-height: 110px; }
.skill-tile[data-status="coming-soon"] .skill-name { filter: grayscale(1); opacity: .42; }
.skill-tile[data-status="coming-soon"] .soon-label { padding: 7px 10px; font-size: .78rem; }
body .course-choices-single { grid-template-columns: minmax(0, 1fr); max-width: 520px; margin-inline: auto; }

/* Shared hub framing, including the main Revision Cards course chooser. */
.course-hub-main .hero { padding: 64px 0 34px; text-align: center; }
.course-hub-main .hero h1 { font-size: clamp(2rem, 4vw, 3rem); margin: 0 0 14px; line-height: 1.6; color: #0f172a; }
.course-hub-main .hero p { max-width: 760px; margin: 0 auto 14px; font-size: 1.05rem; color: #4b5563; }
.course-hub-main .hero-buttons { display: flex; justify-content: center; gap: 14px; flex-wrap: wrap; margin-top: 24px; }
@media (max-width: 650px) {
  .course-hub-main .hero { padding-top: 48px; }
  body .course-choice { padding: 22px; }
}

/* Existing course pages and question controls use the same course tokens. */
body[data-course] :is(.hero .breadcrumb, .unit-label, .eyebrow, .solution-number, .solution-progress, .toggle-state) { color: var(--course-strong); }
body[data-course] :is(.topic-links a, .resource-links a, .mini-links a, .side-box a:not(.btn)) { color: var(--course-strong); }
body[data-course] .feature-list li::before { color: var(--course-accent); }
body[data-course] .pill:not(.easy):not(.medium):not(.hard) { background: var(--course-wash); color: var(--course-strong); }
body[data-course] .hero-stats { border-color: var(--course-line); }
body[data-course] :is(.prerequisite-accordion, .prerequisite-content) { border-color: var(--course-line); }
body[data-course] .prerequisite-accordion { border-top: 4px solid var(--course-accent); }
body[data-course] :is(.prerequisite-content, .prerequisite-toggle[aria-expanded="true"], .prerequisite-toggle:hover) { background: var(--course-pale); }
body[data-course] .toggle-icon { border-color: var(--course-line); background: var(--course-pale); color: var(--course-strong); }
body[data-course] .prerequisite-toggle:hover .toggle-icon { border-color: var(--course-ring); background: var(--course-wash); }
body[data-course] .prerequisite-toggle:focus-visible { outline-color: var(--course-ring); }
body[data-course] :is(.control-btn, .answer-path-btn, .jump-btn) { border-color: var(--course-button); border-radius: 14px; color: var(--course-strong); }
body[data-course] :is(.control-btn, .answer-path-btn, .jump-btn, .carousel-btn):hover:not(:disabled) { background: var(--course-pale); border-color: var(--course-ring); }
body[data-course] .answer-path-btn.active { background: var(--course-button); color: var(--course-button-ink); }
body[data-course] .answer-path-btn.active:hover:not(:disabled) { background: var(--course-button-hover); color: var(--course-button-ink); }
body[data-course] :is(.carousel-btn, .jump-input) { color: var(--course-strong); }
body[data-course] .jump-input:focus { border-color: var(--course-accent); box-shadow: 0 0 0 3px var(--course-wash); }
body[data-course] .jump-input:hover { background: var(--course-pale); border-color: var(--course-ring); }
body[data-course] .toggle-pill.on { background: var(--course-button); }
body[data-course] .context-box { border-left-color: var(--course-ring); }
body[data-course] .mcq-option:hover:not(:disabled):not(.correct):not(.incorrect) { background: var(--course-pale); border-color: var(--course-ring); }
body[data-course] .mcq-option.selected:not(.correct):not(.incorrect) { background: var(--course-pale); border-color: var(--course-accent); box-shadow: 0 0 0 2px var(--course-wash); }
body[data-course] .hero .topic-tag { background: var(--course-pale); color: var(--course-strong); }
body .small-links a[data-course] { color: var(--course-strong); }

/* V72: navigation actions keep one line and share one height. */
body .hero-buttons .btn {
  display: inline-flex; align-items: center; justify-content: center;
  box-sizing: border-box; height: 50px; min-height: 50px;
  width: max-content; min-width: max-content; max-width: 100%; flex: 0 0 auto;
  white-space: nowrap; padding: 0 24px; line-height: 1.4;
}
body .hero-buttons .btn[href$="revision-cards.html"] { min-width: 210px; }
body .hero-buttons .btn[href$="gcse-practice-papers.html"] { min-width: 230px; }
body .hero-buttons.course-page-actions > .btn {
  width: 260px; min-width: 0; max-width: 100%; flex: 0 1 260px;
}
@media (max-width: 600px) {
  body .hero-buttons .btn { font-size: 14px; padding-inline: 16px; }
}

/* V73: the AP prerequisite heading and content form one course-coloured panel. */
body[data-course="ap"] .prerequisite-accordion { background: var(--course-pale); }
body[data-course="ap"] .prerequisite-content {
  margin: 0; padding: 24px 28px 28px; border: 0;
  border-top: 1px solid var(--course-line); border-radius: 0;
  background: var(--course-pale);
}
@media (max-width: 650px) {
  body[data-course="ap"] .prerequisite-content { padding: 20px; }
}

/* V89: side controls follow the question panel, not the solution height. */
.question-navigation-ready > :is(.solution-nav-col, .question-nav-col) {
  position: relative;
  display: block;
  min-width: 0;
}
.question-navigation-ready > :is(.solution-nav-col, .question-nav-col) > .carousel-btn {
  position: absolute;
  top: var(--question-navigation-y, 180px);
  left: 50%;
  transform: translate(-50%, -50%);
  display: grid;
  place-items: center;
  margin: 0;
  padding: 0;
  line-height: 1;
  border-radius: 50%;
}
.carousel-btn > .question-navigation-arrow {
  display: block;
  width: 32px;
  height: 40px;
  max-width: 80%;
  max-height: 80%;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  pointer-events: none;
}
.carousel-btn > .question-navigation-arrow.points-right { transform: rotate(180deg); }

/* V89: shared mathematical figures on main course question pages. */
:is(.solution-question,.solution-body,.question-body,.question-card,#questionContainer,#reviewContainer,.quiz-card,.review-card) .exam-diagram,
.exam-diagram {display:block;box-sizing:border-box;width:100%;max-width:640px;margin:1.15rem auto;padding:0;border:0;background:#fff;color:#171717;text-align:center;}
.exam-diagram img {display:block;width:100%;max-width:640px;height:auto;margin:0 auto;object-fit:contain;}
.exam-diagram figcaption {margin:.55rem auto 0;color:#475569;font-family:inherit;font-size:.82rem;font-weight:400;line-height:1.45;}

/* V114 revision course identities. */
[data-course="ks3"] {
  --course-accent: #168742; --course-button: #168742; --course-button-ink: #fff;
  --course-button-hover: #166534; --course-strong: #166534;
  --course-pale: #f0fdf4; --course-wash: #dcfce7; --course-line: #bbf7d0; --course-ring: #86efac;
}
[data-course="additional"], [data-course-theme="additional"], .revision-dropdown a[href$="gcse-additional-revision-cards.html"] {
  --course-accent: #dc2626; --course-button: #dc2626; --course-button-ink: #fff;
  --course-button-hover: #b91c1c; --course-strong: #b91c1c;
  --course-pale: #fef2f2; --course-wash: #fee2e2; --course-line: #fecaca; --course-ring: #fca5a5;
}

/* Course framing keeps the established page palette. */
body .coming-soon-stamp { border-color: var(--course-strong); color: var(--course-strong); }
body[data-course-theme="additional"] :is(.practice-status, .practice-code, .practice-back) { color: var(--course-strong); }
body[data-course-theme="additional"] .practice-status { background: var(--course-pale); }

body .practice-main :is(.practice-series, .practice-coming, .practice-launch) { border-color: var(--course-accent); }
body .practice-main :is(.practice-code, .practice-status) { background: var(--course-pale); color: var(--course-strong); }
body .practice-main .practice-status::before { background: var(--course-accent); }
body .practice-main :is(.practice-pathway-title, .practice-price-note, .practice-saving, .practice-course-cta, .practice-tier strong, .practice-breadcrumb, .practice-breadcrumb a) { color: var(--course-strong); }
body .practice-main :is(.practice-course, .practice-tier):not(.practice-unavailable) { border-color: var(--course-accent); }
body .practice-main :is(.practice-course, .practice-tier):not(.practice-unavailable):has(a):hover { background: var(--course-pale); }
body .practice-main .practice-stamp { border-color: var(--course-strong); color: var(--course-strong); }
body .practice-main .practice-course-frame { border-color: var(--course-line); background: linear-gradient(135deg, #fff, var(--course-pale)); }
body .practice-main .practice-launch { background: var(--course-pale); }
body .practice-main .practice-bundle { background: var(--course-pale); border-color: var(--course-accent); }
body .practice-main .practice-product .btn:disabled { background: var(--course-button); color: var(--course-button-ink); }
body[data-course-theme="additional"] .practice-main .practice-countdown-clock { background: linear-gradient(135deg, #7f1d1d, #b91c1c 58%, #dc2626); }

/* Keep the shared wordmark within older course-page headers on phones. */
@media (max-width: 700px) {
  body header .brand { font-size: clamp(1.5rem, 7.5vw, 1.8rem); }
}

/* V122: homepage resource text exactly matches its revision-course button. */
body #popular .small-links a[data-course] { color: var(--course-button); }