.notes-start {margin-bottom: 24px; padding: 24px; border-radius: 16px; background: var(--color-bg-alt, #f1f5f9); border: 1px solid var(--color-border, #cbd5e1)}
.notes-eyebrow {font-size: .85rem; font-weight: 700; letter-spacing: .06em; color: var(--color-teal-text, #0f766e)}
.notes-start h2 {margin: 8px 0; font-size: 1.8rem}
.notes-start button {font: inherit; color: var(--color-text); background: transparent; border: 1px solid var(--color-border, #94a3b8); border-radius: 8px; padding: 10px 16px; cursor: pointer}
.notes-chapter {margin: 24px 0; border: 1px solid var(--color-border, #cbd5e1); border-radius: 16px; background: var(--color-bg, #fff)}
.notes-chapter > summary {display: flex; align-items: center; gap: 16px; padding: 24px; cursor: pointer; list-style: none}
.notes-chapter > summary::-webkit-details-marker {display: none}
.notes-chapter__number {color: var(--color-teal-text, #0f766e); font-size: 1.5rem; font-weight: 700}
.notes-chapter > summary strong {font-size: 1.25rem}
.notes-chapter__description {display: block; margin-top: 6px; line-height: 1.5; color: var(--color-text-muted, #64748b)}
.notes-chapter__toggle {margin-left: auto; font-size: 1.6rem}
.notes-chapter[open] > summary .notes-chapter__toggle {transform: rotate(45deg)}
.notes-chapter__body {padding: 0 24px 24px; min-width: 0}
.notes-chapter .topic-section {scroll-margin-top: 110px}
.notes-practice {padding: 24px; margin: 28px 0; border: 1px solid var(--color-teal, #14b8a6); border-radius: 14px; background: var(--color-bg-alt, #f8fafc); font-size: 1rem}
.notes-practice__heading {display: flex; align-items: baseline; justify-content: space-between; gap: 16px}
.notes-practice__heading h3 {margin: 0; font-size: 1.2rem}
.notes-practice__heading > span {white-space: nowrap; font-weight: 700}
.notes-practice__access {color: var(--color-text-muted, #64748b); line-height: 1.6}
.notes-practice label {display: block; font-weight: 600; margin-bottom: 8px}
.notes-practice textarea {box-sizing: border-box; width: 100%; resize: vertical; padding: 12px; font: inherit; line-height: 1.6; color: var(--color-text, #0f172a); background: var(--color-bg, #fff); border: 1px solid var(--color-border, #94a3b8); border-radius: 8px}
.notes-practice details {margin-top: 14px}
.notes-practice summary {cursor: pointer; padding: 12px 0; font-weight: 600}
.notes-practice ol {padding-left: 24px; line-height: 1.8}
.notes-practice :focus-visible, .notes-chapter > summary:focus-visible {outline: 3px solid #14b8a6; outline-offset: 4px}
@media(max-width:600px) {.notes-chapter > summary {padding: 18px 14px; gap: 10px}.notes-chapter__body {padding: 0 12px 16px}.notes-practice {padding: 16px}.notes-start {padding: 18px}.notes-practice__heading {flex-wrap: wrap; gap: 6px}}
@media print {.notes-start button {display:none}.notes-chapter__body {display:block!important}.notes-chapter {break-inside:auto}}
.notes-nav-group > summary {padding: 12px 0; cursor: pointer; font-weight: 600; line-height: 1.5}
.notes-nav-group .topic-sidebar__list {margin-top: 6px}
.notes-definitions {margin-bottom: 20px}
.notes-definitions > summary {padding: 12px 0; cursor: pointer; font-weight: 600}

/* Topic overview and practice journey */
.notes-start {display:grid; grid-template-columns:1.15fr 1fr; gap:32px; padding:32px; background:linear-gradient(125deg,#102d37,#174b50); color:#fff; border:0; border-radius:22px; overflow:hidden}
.notes-start .notes-eyebrow {color:#8ce9d7; margin:0 0 16px; font-size:.8rem}
.notes-start h2 {color:#fff; font-size:clamp(1.8rem,3vw,2.4rem); line-height:1.15; letter-spacing:-.04em; margin:0 0 18px}
.notes-start__copy > p:last-child {color:#d3e8e8; line-height:1.65; margin:0; max-width:32ch}
.notes-path {list-style:none; padding:0; margin:0; display:grid; align-content:center; gap:20px}
.notes-path li {display:flex; gap:14px; align-items:center}
.notes-path li > span {display:grid; place-items:center; width:38px; height:38px; flex-shrink:0; border:1px solid #70c7b9; border-radius:50%; color:#9aefdd; font-size:.85rem; font-weight:700}
.notes-path strong {display:block; color:#fff; font-size:1rem}
.notes-path small {display:block; color:#c6dedf; font-size:.9rem; margin-top:4px; line-height:1.4}
.notes-section-heading {display:flex; justify-content:space-between; align-items:center; gap:16px; margin:32px 0 12px}
.notes-section-heading h2 {font-size:1.4rem; margin:0}
.notes-section-heading button {font:inherit; font-size:.9rem; font-weight:600; cursor:pointer; color:var(--color-text); padding:10px 14px; border:1px solid var(--color-border,#cbd5e1); border-radius:10px; background:var(--color-bg,#fff)}
.notes-definitions {font-size:.95rem; margin:0 0 20px}
.notes-chapter {--chapter-accent:#14796c; --chapter-tint:#e3f5ee; margin:16px 0; background:var(--color-bg,#fff); box-shadow:0 5px 18px #122b3510; border-radius:18px; transition:box-shadow .2s}
.notes-chapter[data-chapter="2"] {--chapter-accent:#6952ad; --chapter-tint:#efeafa}
.notes-chapter[data-chapter="3"] {--chapter-accent:#2c6dad; --chapter-tint:#e7f0fb}
.notes-chapter[data-chapter="4"] {--chapter-accent:#95601f; --chapter-tint:#fcf0db}
.notes-chapter > summary {padding:22px; gap:22px}
.notes-chapter > summary:hover {box-shadow:inset 0 0 0 2px var(--chapter-accent); border-radius:18px}
.notes-chapter__number {width:88px; height:88px; flex-shrink:0; display:flex; flex-direction:column; justify-content:space-between; align-items:flex-start; padding:10px; border-radius:14px; background:var(--chapter-tint); color:var(--chapter-accent); box-sizing:border-box}
.notes-chapter__number > span {font-size:.8rem; line-height:1}
.notes-chapter__number b {font-size:1.1rem; align-self:center; white-space:nowrap; padding-bottom:8px}
.notes-chapter__copy {min-width:0}
.notes-chapter__meta {display:block; font-size:.75rem; font-weight:600; letter-spacing:.035em; color:var(--color-text-muted,#64748b); margin-bottom:8px}
.notes-chapter > summary strong {display:block; font-size:1.3rem; letter-spacing:-.02em; line-height:1.3}
.notes-chapter__description {font-size:.95rem}
.notes-chapter__toggle {display:grid; place-items:center; width:32px; height:32px; flex-shrink:0; border-radius:50%; background:var(--chapter-tint); color:var(--chapter-accent); font-size:1.3rem}
.notes-chapter[open] > summary {border-bottom:1px solid var(--color-border,#e2e8f0); margin-bottom:24px}
.notes-practice {border:1px solid #a99bdf; border-top:4px solid #7854cf; box-shadow:0 8px 24px #48377b0c; background:var(--color-bg,#fff)}
.notes-practice__heading h3 {font-size:1.2rem}
.notes-practice__heading > span {padding:5px 10px; border-radius:7px; background:#eee9fa; color:#59408c; font-size:.9rem}
.notes-practice__access {font-size:1rem; line-height:1.6}
.notes-locked-answer > summary {display:flex; justify-content:center; gap:12px; padding:15px 18px; border-radius:10px; color:#fff; background:#6943bb; list-style:none; text-align:center; line-height:1.45}
.notes-locked-answer > summary::-webkit-details-marker {display:none}
.notes-locked-answer > summary:hover {background:#543199}
.notes-practice__allowance {font-size:.9rem; line-height:1.6; color:var(--color-text-muted,#64748b); margin-bottom:0}
.notes-practice__allowance a {color:inherit; text-underline-offset:3px}
@media(max-width:700px) {.notes-start {grid-template-columns:1fr; padding:24px; gap:26px}.notes-path {gap:16px}.notes-chapter > summary {padding:16px; gap:14px}.notes-chapter__number {width:60px;height:72px;padding:8px}.notes-chapter__number b {font-size:.8rem}.notes-chapter > summary strong {font-size:1.1rem}.notes-chapter__meta {font-size:.7rem}.notes-chapter__description {font-size:.9rem}.notes-section-heading {align-items:flex-start}.notes-section-heading h2 {font-size:1.2rem}.notes-section-heading button {font-size:.8rem}.notes-chapter__toggle {width:25px;height:25px}.notes-chapter__body {padding:0 6px 12px}.notes-chapter .topic-section {padding:18px 12px}}
@media(prefers-reduced-motion:reduce) {.notes-chapter {transition:none}}

/* Illustrated chapter covers and a visual account invitation. */
.notes-chapter {background:var(--color-surface,#fff); border-color:transparent; box-shadow:0 3px 5px #183a4510,0 14px 32px #183a4507; overflow:hidden}
.notes-chapter > summary {padding:0 24px 0 0; gap:26px; min-height:150px}
.notes-chapter__art.topic-diagram {display:grid; align-items:center; flex:0 0 184px; width:184px; align-self:stretch; margin:0; padding:0; border:0; border-radius:0; background:var(--chapter-tint); color:var(--chapter-accent); box-shadow:none; overflow:hidden}
.notes-chapter__art svg {display:block; width:100%; max-width:240px; height:auto; transition:transform .2s ease}
.notes-chapter > summary:hover .notes-chapter__art svg {transform:translateY(-3px) rotate(-2deg)}
.notes-chapter > summary:hover {box-shadow:none; background:var(--color-surface-raised,#f8fafc)}
.notes-chapter > summary strong {font-size:1.35rem; font-weight:750}
.notes-chapter__meta {font-size:.75rem; margin-bottom:10px}
.notes-chapter__toggle {background:var(--color-surface-sunken,#f1f5f9); color:var(--color-text,#0f172a); width:36px; height:36px}
.notes-practice {background:var(--color-surface,#fff); padding:28px; border:1px solid var(--color-border,#dbe2eb); border-radius:20px; box-shadow:0 10px 32px #3425570b}
.notes-practice .notes-practice__heading h3 {font-size:1.2rem; margin:0; color:var(--color-text,#0f172a)}
.notes-practice p {font-size:1rem; line-height:1.65}
.notes-practice .notes-practice__access {display:flex; gap:8px; flex-wrap:wrap; margin:16px 0 24px}
.notes-access-chip {font-size:.8rem; font-weight:600; color:#146b56; background:#e7f6ef; padding:6px 10px; border-radius:6px; line-height:1.4}
.notes-access-chip--locked {color:#624598; background:#f1ecfb}
.notes-practice textarea {background:var(--color-surface-raised,#f8fafc)}
.notes-unlock-preview {display:flex; align-items:center; gap:28px; padding:26px 0 20px; margin-top:16px; border-top:1px solid var(--color-border,#e2e8f0)}
.notes-mark-preview {position:relative; flex:0 0 160px; padding:18px 14px; border:1px solid #ded7f1; background:linear-gradient(145deg,#faf8ff,#ede7f8); border-radius:12px; transform:rotate(-4deg); box-shadow:0 6px 0 -2px #e5def4; box-sizing:border-box}
.notes-preview-tag {display:block; color:#70589c; font-size:9px; letter-spacing:.08em; font-weight:700; margin-bottom:13px}
.notes-mark-preview > div {display:flex; align-items:center; gap:8px; margin:9px 0}
.notes-mark-preview i {font-style:normal; color:#21876e; font-size:15px}
.notes-mark-preview div > span {height:6px; width:72px; background:#c5b8dc; border-radius:5px}
.notes-mark-preview div:nth-of-type(2) > span {width:52px}
.notes-mark-preview b {color:#715894; font-size:11px; margin-left:auto}
.notes-mark-preview em {position:absolute; right:-8px; bottom:-8px; width:32px; height:32px; display:grid; place-items:center; border-radius:50%; background:#6943bb; color:white; box-shadow:0 0 0 4px var(--color-surface,#fff)}
.notes-mark-preview em svg {width:16px; height:16px}
.notes-unlock-copy .notes-eyebrow {color:#7b5ab5; font-size:.7rem; letter-spacing:.1em}
.notes-practice .notes-unlock-copy h4 {margin:7px 0; color:var(--color-text,#0f172a); font-size:1.35rem; line-height:1.3; letter-spacing:-.025em}
.notes-practice .notes-unlock-copy p {font-size:.95rem; margin:0; line-height:1.6; color:var(--color-text-muted,#64748b)}
.notes-practice .notes-locked-answer {margin-top:10px}
.notes-locked-answer > summary {padding:14px 20px; font-size:1rem; border-radius:12px; box-shadow:0 4px 10px #6943bb20}
.notes-access-options {display:grid; grid-template-columns:1fr 1fr; gap:12px; margin-top:18px}
.notes-access-options > * {display:flex; gap:14px; align-items:center; justify-content:center; padding:12px; background:var(--color-surface-raised,#f8fafc); border:1px solid var(--color-border,#e2e8f0); border-radius:10px; text-decoration:none; color:var(--color-text,#0f172a)}
.notes-access-options strong {font-size:1.5rem; line-height:1.2; color:#7754b2}
.notes-access-options strong span {font-size:.75rem; font-weight:500; color:var(--color-text-muted,#64748b)}
.notes-access-options > * > span {font-size:.85rem; font-weight:600}
.notes-access-options a:hover {border-color:#7754b2}
.notes-practice .notes-practice__allowance {font-size:.8rem; text-align:center; margin:12px 0 0; color:var(--color-text-muted,#64748b)}
.notes-practice--unlocked .notes-unlock-preview,.notes-practice--unlocked .notes-access-options,.notes-practice--unlocked .notes-practice__allowance {display:none}
@media(max-width:700px) {
 .notes-chapter > summary {gap:16px; padding:0 14px 0 0; min-height:135px}
 .notes-chapter__art.topic-diagram {flex-basis:100px; width:100px}
 .notes-chapter > summary strong {font-size:1.05rem}
 .notes-chapter__description {font-size:.85rem; line-height:1.45}
 .notes-chapter__meta {font-size:.65rem; margin-bottom:6px}
 .notes-chapter__toggle {width:26px;height:26px}
 .notes-practice {padding:18px}
 .notes-unlock-preview {gap:16px; padding-top:24px}
 .notes-mark-preview {flex-basis:110px; padding:12px 9px}
 .notes-mark-preview div > span {width:43px}
 .notes-mark-preview div:nth-of-type(2) > span {width:32px}
 .notes-practice .notes-unlock-copy h4 {font-size:1.15rem}
 .notes-practice .notes-unlock-copy p {font-size:.85rem}
 .notes-access-options > * {flex-direction:column; gap:4px; padding:10px 6px}
}
@media(max-width:420px) {.notes-chapter__art.topic-diagram {flex-basis:76px;width:76px}.notes-chapter > summary {gap:12px}.notes-chapter__description {display:none}.notes-unlock-preview {gap:14px}.notes-mark-preview {flex-basis:96px}.notes-mark-preview div > span {width:31px}}
@media(prefers-reduced-motion:reduce) {.notes-chapter__art svg {transition:none}.notes-chapter > summary:hover .notes-chapter__art svg {transform:none}}

/* Illustrated next steps, scoped to this section. */
.notes-next {margin-top:48px; scroll-margin-top:100px}
.notes-next__heading {margin-bottom:24px}
.notes-next__heading .notes-eyebrow {font-size:.75rem; margin-bottom:8px}
.notes-next__heading h2 {font-size:1.65rem; letter-spacing:-.03em; margin:0}
.notes-tools {display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:18px}
.notes-tool {--tool-tint:#e6f6f0; --tool-ink:#278577; display:flex; align-items:stretch; min-width:0; overflow:hidden; background:var(--color-surface,#fff); border:1px solid var(--color-border,#e2e8f0); border-radius:18px; text-decoration:none; color:var(--color-text,#0f172a); box-shadow:0 8px 22px #183a4506; transition:transform .2s,box-shadow .2s}
.notes-tool--explore {--tool-tint:#e9f1fc;--tool-ink:#4d7db7}
.notes-tool--recall {--tool-tint:#fff3df;--tool-ink:#a7772c}
.notes-tool--practise {--tool-tint:#f0eafa;--tool-ink:#8160b9}
.notes-tool__art.topic-diagram {flex:0 0 30%; width:30%; margin:0; padding:0; background:var(--tool-tint); color:var(--tool-ink); display:grid; place-items:center; border:0; border-radius:0; box-shadow:none}
.notes-tool__art svg,.notes-onward__art svg,.notes-pocket__art svg {width:100%; max-width:240px; height:auto; display:block}
.notes-tool__copy {padding:24px 18px; min-width:0; display:flex; flex-direction:column; align-items:flex-start}
.notes-tool__eyebrow {font-size:.65rem; font-weight:700; letter-spacing:.12em; color:var(--tool-ink)}
.notes-tool h3 {font-size:1.1rem; line-height:1.35; margin:8px 0; letter-spacing:-.02em; color:var(--color-text,#0f172a)}
.notes-tool p {font-size:.9rem; line-height:1.55; margin:0 0 18px; color:var(--color-text-muted,#64748b)}
.notes-tool__cta {font-size:.85rem; font-weight:650; display:flex; align-items:center; gap:10px; margin-top:auto}
.notes-tool__cta > span {color:var(--tool-ink)}
.notes-tool:hover {transform:translateY(-3px); box-shadow:0 12px 26px #183a4512; border-color:var(--tool-ink)}
.notes-tool:focus-visible,.notes-onward a:focus-visible,.notes-pocket a:focus-visible {outline:3px solid #14b8a6;outline-offset:4px}
.notes-onward {margin-top:32px}
.notes-onward__link {display:flex; align-items:center; gap:32px; padding:28px 32px; border-radius:20px; background:linear-gradient(120deg,#173c43,#142a38); color:#fff; text-decoration:none; border:1px solid #31565c; transition:box-shadow .2s}
.notes-onward__art.topic-diagram {width:180px; flex:0 0 180px; margin:0; padding:0; color:#8de0d0; background:transparent; box-shadow:none; border:0}
.notes-onward__eyebrow {font-size:.75rem; letter-spacing:.1em; color:#9ce7d9; font-weight:650}
.notes-onward h2 {font-size:1.65rem; line-height:1.2; letter-spacing:-.03em; margin:10px 0; color:#fff}
.notes-onward p {font-size:.95rem; color:#d0e4e7; line-height:1.6; margin:0 0 18px; max-width:42ch}
.notes-onward__cta {display:inline-flex; align-items:center; gap:16px; font-size:.9rem; font-weight:650; color:#b7f1e6}
.notes-onward__link:hover {box-shadow:0 8px 24px #12343d25}
.notes-pocket {display:flex; align-items:center; gap:24px; margin-top:24px; padding:22px 32px; border:1px solid var(--color-border,#dce5e9); border-radius:20px; background:var(--color-surface,#fff)}
.notes-pocket__art.topic-diagram {flex:0 0 140px; width:140px; margin:0; padding:0; border:0; box-shadow:none; background:transparent; color:#258e80}
.notes-pocket .notes-eyebrow {font-size:.7rem; letter-spacing:.08em}
.notes-pocket h3 {font-size:1.3rem; letter-spacing:-.02em; margin:8px 0; color:var(--color-text,#0f172a)}
.notes-pocket p {font-size:.95rem; margin:0 0 14px; color:var(--color-text-muted,#64748b); line-height:1.5}
.notes-pocket a {font-size:.9rem; font-weight:650; color:var(--color-text,#0f172a); text-decoration:none; display:inline-flex; gap:14px; padding:8px 0}
.notes-pocket a:hover {text-decoration:underline;text-underline-offset:4px}
@media(max-width:700px) {
 .notes-tools {grid-template-columns:1fr;gap:14px}
 .notes-tool__art.topic-diagram {flex-basis:32%;width:32%}
 .notes-tool__copy {padding:20px 16px}
 .notes-onward__link {padding:24px 20px;gap:16px}
 .notes-onward__art.topic-diagram {flex-basis:100px;width:100px}
 .notes-onward h2 {font-size:1.4rem}
 .notes-pocket {padding:20px 16px;gap:12px}
 .notes-pocket__art.topic-diagram {flex-basis:90px;width:90px}
 .notes-pocket h3 {font-size:1.15rem}
}
@media(max-width:420px) {.notes-onward__link {position:relative;display:block}.notes-onward__art.topic-diagram {float:right;width:88px;margin:0 0 8px 8px}.notes-onward__eyebrow {font-size:.65rem}.notes-onward p {clear:both}}
@media(prefers-reduced-motion:reduce) {.notes-tool,.notes-onward__link {transition:none}.notes-tool:hover {transform:none}}

/* Section welcome and chapter navigator. */
.notes-hero {padding:40px 0 40px; background:linear-gradient(120deg,#122d39,#183e47); overflow:hidden}
.notes-hero::before {display:none}
.notes-hero__layout {display:grid;grid-template-columns:minmax(0,1.4fr) minmax(280px,1fr);column-gap:60px;align-items:center;position:relative}
.notes-hero__copy {grid-column:1;grid-row:1}
.notes-hero .topic-hero__breadcrumb {font-size:.85rem;margin:0 0 32px;color:#aac8cf}
.notes-hero .topic-hero__breadcrumb a {color:#d9eeee}
.notes-hero__eyebrow {font-size:.75rem;font-weight:650;letter-spacing:.14em;color:#94dece;margin:0 0 16px}
.notes-hero h1 {font-size:clamp(2rem,4vw,3.3rem);line-height:1.08;letter-spacing:-.045em;max-width:20ch;margin:0 0 20px}
.notes-hero h1 span {display:block;color:#a4e8d8}
.notes-hero .topic-hero__desc {font-size:1.05rem;line-height:1.65;max-width:43ch;color:#d4e4e7;margin:0 0 22px}
.notes-hero__facts {display:flex;gap:0;flex-wrap:wrap;color:#c6dcdf;font-size:.8rem;margin-bottom:26px}
.notes-hero__facts > span + span::before {content:'·';padding:0 12px;color:#8ac7bd}
.notes-hero__start {display:inline-flex;align-items:center;gap:32px;padding:14px 20px;border-radius:12px;background:#b5f0df;color:#123a38;text-decoration:none;font-size:.95rem;font-weight:700;box-shadow:0 6px 20px #071f2525}
.notes-hero__start:hover {background:#d0faef}
.notes-hero #edexcel-progress-toggle {grid-column:1;justify-self:start;margin-top:16px!important;background:transparent;color:#d1e5e7;border:1px solid #577b82;font-size:.8rem;padding:8px 14px}
.notes-hero #edexcel-progress-toggle[data-state="done"] {background:#b5f0df;color:#123a38}
.notes-hero #edexcel-progress-toggle[data-state="in-progress"] {background:#fefce8;color:#92400e;border-color:#fde68a}
.notes-hero__visual {grid-column:2;grid-row:1 / span 2;position:relative;height:340px;max-width:430px;width:100%;justify-self:center}
.notes-hero__orbit {position:absolute;inset:6px 14px;border:1px solid #9ce7d921;border-radius:50%;transform:rotate(-20deg)}
.notes-hero__orbit::after {content:'';position:absolute;inset:28px -18px;border:1px solid #9ce7d91c;border-radius:50%;transform:rotate(55deg)}
.notes-hero__atom {position:absolute;left:6%;top:12px;width:72%;padding:20px 16px 16px;border:1px solid #ffffff50;border-radius:22px;background:#edf6f4;color:#637fc0;transform:rotate(-7deg);box-shadow:0 18px 40px #071a3035;box-sizing:border-box}
.notes-hero__atom > span {display:block;font-size:.65rem;letter-spacing:.12em;color:#4a6e78;font-weight:700}
.notes-hero__atom svg {display:block;width:100%;max-width:300px;height:auto}
.notes-hero__atom > div {display:flex;align-items:center;justify-content:center;gap:5px;font-size:.55rem;color:#405967;white-space:nowrap}
.notes-hero__atom i {display:block;width:5px;height:5px;border-radius:50%;background:#637fc0}
.notes-hero__atom i:nth-of-type(2) {background:#b4a1ea}
.notes-hero__atom i:nth-of-type(3) {background:#9580d3}
.notes-hero__table {position:absolute;right:0;bottom:6px;width:55%;background:#d0ebdf;color:#317c70;border:1px solid #ebfff6;border-radius:16px;transform:rotate(8deg);padding:8px 10px 15px;box-shadow:0 12px 24px #071a3030}
.notes-hero__table svg {display:block;width:100%;max-width:240px;height:auto}
.notes-hero__table > span {display:block;font-size:.7rem;text-align:center;font-weight:600;color:#2b635b}
.notes-hero__spark {position:absolute;color:#b9eadb;font-size:2rem;font-weight:300}
.notes-hero__spark--one {right:12px;top:16px}.notes-hero__spark--two {left:0;bottom:20px;font-size:1.4rem}
.notes-sidebar .topic-sidebar__inner {padding:22px 16px;border:1px solid var(--color-border,#e2e8f0);border-radius:20px;box-shadow:0 8px 24px #14364008}
.notes-sidebar__heading {padding:0 8px 18px;border-bottom:1px solid var(--color-border,#e2e8f0);margin-bottom:12px}
.notes-sidebar__heading > span {display:block;font-size:.65rem;letter-spacing:.12em;font-weight:700;color:var(--color-teal-text,#0f766e);margin-bottom:8px}
.notes-sidebar__heading strong {display:block;font-size:1.1rem;letter-spacing:-.02em;color:var(--color-text,#334155)}
.notes-sidebar__heading p {font-size:.8rem;color:var(--color-text-muted,#64748b);margin:6px 0 0}
.notes-sidebar .notes-nav-group {--nav-tint:#e6f6ef;--nav-ink:#2a8777;border-radius:12px;margin:5px 0}
.notes-sidebar .notes-nav-group[data-chapter="2"] {--nav-tint:#f0eafa;--nav-ink:#7c61b2}
.notes-sidebar .notes-nav-group[data-chapter="3"] {--nav-tint:#e9f1fc;--nav-ink:#4d7db7}
.notes-sidebar .notes-nav-group[data-chapter="4"] {--nav-tint:#fff3df;--nav-ink:#a7772c}
.notes-sidebar .notes-nav-group > summary {display:flex;align-items:center;gap:10px;list-style:none;padding:12px 7px;font-size:.85rem;line-height:1.45;font-weight:600;color:var(--color-text,#334155);border-radius:10px}
.notes-sidebar .notes-nav-group > summary::-webkit-details-marker {display:none}
.notes-sidebar .notes-nav-group > summary:hover,.notes-sidebar .notes-nav-group[open] > summary {background:var(--color-surface-raised,#f8fafc)}
.notes-nav-icon {display:grid;place-items:center;flex:0 0 42px;height:46px;background:var(--nav-tint);color:var(--nav-ink);border-radius:9px}
.notes-nav-icon svg {display:block;width:100%;height:auto;max-width:60px}
.notes-sidebar summary small {display:block;font-size:.55rem;letter-spacing:.08em;color:var(--color-text-muted,#64748b);margin-bottom:3px}
.notes-sidebar summary b {font-size:1rem;font-weight:400;margin-left:auto;color:var(--color-text-muted,#64748b)}
.notes-sidebar .notes-nav-group[open] > summary b {transform:rotate(45deg)}
.notes-sidebar .notes-nav-group .topic-sidebar__list {display:flex;max-height:none;overflow:visible;margin:6px 0 14px 25px;padding-left:13px;border-left:1px solid var(--color-border,#e2e8f0);gap:2px}
.notes-sidebar .topic-sidebar__link {font-size:.8rem;padding:8px 10px;border:0;line-height:1.5}
.notes-sidebar__practice {display:flex;gap:12px;align-items:center;padding:15px 12px;margin-top:18px;border-radius:12px;background:var(--color-surface-sunken,#f1f5f9);color:var(--color-text,#334155);text-decoration:none;font-size:.8rem;font-weight:650}
.notes-sidebar__practice > span:first-child {font-size:1.4rem;color:#8160b9}
.notes-sidebar__practice small {display:block;font-size:.7rem;font-weight:400;margin-top:5px;color:var(--color-text-muted,#64748b)}
.notes-sidebar .topic-sidebar__top {font-size:.75rem;margin:14px 0 0;padding:8px 12px}
.notes-sidebar :focus-visible,.notes-hero a:focus-visible {outline:3px solid #14b8a6;outline-offset:3px}
.notes-start {display:block;background:var(--color-surface,#fff);border:1px solid var(--color-border,#e2e8f0);padding:22px 24px;box-shadow:none}
.notes-path {display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
.notes-path li {gap:10px;align-items:flex-start}
.notes-path li > span {width:30px;height:30px;border:0;border-radius:9px;background:#e6f6ef;color:#287c6e;font-size:.7rem}
.notes-path strong {color:var(--color-text,#334155);font-size:.9rem}
.notes-path small {color:var(--color-text-muted,#64748b);font-size:.75rem;line-height:1.5}
@media(max-width:900px) {.notes-hero__layout {column-gap:24px;grid-template-columns:minmax(0,1.4fr) minmax(220px,1fr)}.notes-hero__visual {height:285px}.notes-sidebar {cursor:default}.notes-sidebar .topic-sidebar__inner {padding:18px}.notes-sidebar__heading {padding-bottom:12px}.notes-sidebar .notes-nav-group > summary {padding:10px}.notes-sidebar .notes-nav-group .topic-sidebar__list {max-height:none}.notes-sidebar__practice {margin-top:12px}}
@media(max-width:600px) {.notes-hero {padding:28px 0 28px}.notes-hero__layout {display:flex;flex-direction:column;align-items:stretch;gap:0}.notes-hero .topic-hero__breadcrumb {margin-bottom:24px}.notes-hero h1 {font-size:2.15rem}.notes-hero__visual {height:235px;width:280px;align-self:center;margin-top:24px;order:3}.notes-hero__atom {width:67%;padding:14px 12px}.notes-hero__atom > div {font-size:.4rem;gap:3px}.notes-hero__atom > span {font-size:.5rem}.notes-hero__table {width:50%;right:0;bottom:0}.notes-hero__facts {font-size:.72rem}.notes-hero #edexcel-progress-toggle {align-self:flex-start}.notes-hero .topic-hero__desc {font-size:1rem}.notes-start {padding:18px}.notes-path {grid-template-columns:1fr;gap:14px}.notes-path li {align-items:center}.notes-path small {margin-top:2px}.notes-section-heading {margin-top:24px}}

.notes-previous {display:flex;justify-content:space-between;gap:20px;margin-top:24px;font-size:.85rem}
.notes-previous a {color:var(--color-text-muted,#64748b);text-underline-offset:4px}
.notes-previous a:focus-visible {outline:3px solid #14b8a6;outline-offset:4px}

/* ══════════════════════════════════════════════════════════════
   "Try an exam-style question" in the notes: exam paper look to match the
   exam questions (header strip, exam serif, ruled answer lines, slim rows).
   Behaviour is unchanged (topic-notes.js).
   ══════════════════════════════════════════════════════════════ */
.notes-practice {
    --np-ink: var(--color-navy, #0f172a);
    --np-text: var(--color-text, #334155);
    --np-muted: var(--color-text-muted, #64748b);
    --np-bg: var(--color-surface, #fff);
    --np-raised: var(--color-surface-raised, #f8fafc);
    --np-edge: #e3e9f0;
    --np-rule: #e6ecf2;
    --np-accent: var(--color-teal-text, #0f766e);
    --np-serif: "Iowan Old Style", Charter, "Palatino Linotype", Georgia, serif;
}
[data-theme="dark"] .notes-practice { --np-edge: rgba(255, 255, 255, .1); --np-rule: rgba(148, 163, 184, .18); --np-accent: #5eead4; }
.notes-practice:not(#np) {
    padding: 0 0 1.3rem;
    margin: 32px 0;
    overflow: hidden;
    background: var(--np-bg);
    border: 1px solid var(--np-edge);
    border-top: 1px solid var(--np-edge);
    border-radius: 20px;
    box-shadow: 0 1px 2px rgba(15, 23, 42, .05), 0 22px 44px -28px rgba(15, 23, 42, .3);
}
[data-theme="dark"] .notes-practice:not(#np) { box-shadow: 0 22px 44px -28px rgba(0, 0, 0, .7); }
.notes-practice:not(#np) > :not(.notes-practice__heading) { margin-left: 1.5rem; margin-right: 1.5rem; }
.notes-practice:not(#np) > textarea { width: calc(100% - 3rem); max-width: calc(100% - 3rem); box-sizing: border-box; }

/* Header strip */
.notes-practice:not(#np) > .notes-practice__heading {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin: 0 0 1.2rem;
    padding: .8rem 1.5rem;
    background: linear-gradient(90deg, color-mix(in srgb, var(--color-teal, #14b8a6) 11%, var(--np-bg)), var(--np-bg) 65%);
    border-bottom: 1px solid var(--np-edge);
}
.notes-practice:not(#np) .notes-practice__heading h3 {
    display: inline-flex;
    align-items: center;
    gap: .5rem;
    margin: 0;
    font-size: .74rem;
    font-weight: 800;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--np-accent);
}
.notes-practice:not(#np) .notes-practice__heading h3::before {
    content: "";
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--color-teal, #14b8a6);
    box-shadow: 0 0 0 4px color-mix(in srgb, var(--color-teal, #14b8a6) 20%, transparent);
}
.notes-practice:not(#np) .notes-practice__heading > span {
    padding: .15rem .6rem;
    border-radius: 999px;
    font-size: .78rem;
    font-weight: 700;
    color: var(--np-accent);
    background: color-mix(in srgb, var(--color-teal, #14b8a6) 12%, transparent);
    border: 1px solid color-mix(in srgb, var(--color-teal, #14b8a6) 25%, transparent);
}

/* Access line and the question itself */
.notes-practice:not(#np) .notes-practice__access { margin-top: 0; margin-bottom: .9rem; font-size: .88rem; color: var(--np-muted); }
.notes-practice:not(#np) .notes-access-chip { border-radius: 999px; padding: 4px 10px; font-size: .76rem; }
.notes-practice:not(#np) > p:not([class]) {
    margin-top: 0;
    margin-bottom: 1.1rem;
    font: 600 1.2rem/1.5 var(--np-serif);
    color: var(--np-ink);
    text-wrap: pretty;
}
.notes-practice:not(#np) > label {
    margin-bottom: .45rem;
    font-size: .74rem;
    font-weight: 700;
    letter-spacing: .06em;
    text-transform: uppercase;
    color: var(--np-muted);
}

/* Ruled answer lines inside a soft multi-colour edge */
.notes-practice:not(#np) textarea {
    display: block;
    min-height: 132px;
    padding: 4px 16px 12px;
    border: 1.5px solid transparent;
    border-radius: 14px;
    font: 1rem/32px var(--font-family, Inter, system-ui, sans-serif);
    color: var(--np-ink);
    background:
        linear-gradient(transparent 0 31px, var(--np-rule) 31px 32px) padding-box,
        linear-gradient(var(--np-bg), var(--np-bg)) padding-box,
        conic-gradient(from 200deg, #14b8a6, #3b82f6, #8b5cf6, #ec4899, #f59e0b, #14b8a6) border-box;
    background-size: 100% 32px, auto, auto;
    background-position: 0 4px, 0 0, 0 0;
    background-attachment: local, scroll, scroll;
    box-shadow: 0 0 22px -12px rgba(139, 92, 246, .45);
    transition: box-shadow .3s ease;
}
.notes-practice:not(#np) textarea:focus { outline: none; box-shadow: 0 0 28px -8px rgba(139, 92, 246, .55); }
.notes-practice:not(#np) textarea::placeholder { color: var(--np-muted); opacity: .8; }

/* Hint and free mark scheme: slim rows like the exam papers */
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer) {
    margin-top: .8rem;
    border: 1px dashed color-mix(in srgb, var(--np-muted) 45%, transparent);
    border-radius: 12px;
    overflow: hidden;
}
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer)[open] { border-style: solid; border-color: var(--np-edge); }
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer) > summary {
    display: flex;
    align-items: center;
    gap: .6rem;
    padding: .7rem .95rem;
    list-style: none;
    background: var(--np-raised);
    font-size: .9rem;
    font-weight: 600;
    color: var(--np-ink);
}
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer) > summary::-webkit-details-marker { display: none; }
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer) > summary::after { content: "→"; margin-left: auto; color: var(--np-accent); font-weight: 700; transition: transform .2s ease; }
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer)[open] > summary::after { transform: rotate(90deg); }
.notes-practice:not(#np) .notes-hint > summary::before { content: "💡"; font-size: .9rem; }
.notes-practice:not(#np) .notes-free-answer > summary::before {
    content: "";
    width: 16px;
    height: 16px;
    background: var(--np-muted);
    -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z'/%3E%3Cpath d='M14 2v6h6M9 13h6M9 17h4'/%3E%3C/svg%3E") center / contain no-repeat;
            mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z'/%3E%3Cpath d='M14 2v6h6M9 13h6M9 17h4'/%3E%3C/svg%3E") center / contain no-repeat;
}
.notes-practice:not(#np) :is(.notes-hint, .notes-free-answer) > :not(summary) { margin: 0; padding: .8rem 1rem; border-top: 1px solid var(--np-edge); background: var(--np-bg); color: var(--np-text); font-size: .93rem; }

/* Locked mark scheme: calmer preview and a navy unlock button */
.notes-practice:not(#np) .notes-unlock-preview { border-top-color: var(--np-edge); }
.notes-practice:not(#np) .notes-mark-preview { border-color: var(--np-edge); background: linear-gradient(145deg, var(--np-raised), color-mix(in srgb, var(--color-teal, #14b8a6) 10%, var(--np-bg))); }
.notes-practice:not(#np) .notes-mark-preview em { background: var(--np-ink); color: var(--np-bg); }
.notes-practice:not(#np) .notes-unlock-copy .notes-eyebrow,
.notes-practice:not(#np) .notes-access-options strong { color: var(--np-accent); }
.notes-practice:not(#np) .notes-unlock-copy h4 { font-family: var(--np-serif); font-weight: 600; letter-spacing: 0; color: var(--np-ink); }
.notes-practice:not(#np) .notes-locked-answer > summary { background: var(--np-ink); color: var(--np-bg); box-shadow: none; }
.notes-practice:not(#np) .notes-locked-answer > summary:hover { background: var(--np-ink); filter: brightness(1.15); }
.notes-practice:not(#np) .notes-access-options a:hover { border-color: var(--color-teal, #14b8a6); }

@media (max-width: 600px) {
    .notes-practice:not(#np) > :not(.notes-practice__heading) { margin-left: 1rem; margin-right: 1rem; }
    .notes-practice:not(#np) > textarea { width: calc(100% - 2rem); max-width: calc(100% - 2rem); }
    .notes-practice:not(#np) > .notes-practice__heading { padding: .7rem 1rem; }
    .notes-practice:not(#np) > p:not([class]) { font-size: 1.08rem; }
}