@import url("https://fonts.googleapis.com/css2?family=Manrope:wght@400;500;600;700;800&family=Space+Grotesk:wght@500;600;700&display=swap");

:root {
    --diff-bg: #050814;
    --diff-bg-deep: #03050d;
    --diff-panel: rgba(12, 20, 42, 0.72);
    --diff-panel-strong: rgba(17, 28, 57, 0.94);
    --diff-text: #edf4ff;
    --diff-muted: #a5b9d3;
    --diff-blue: #6f92ff;
    --diff-cyan: #5ce7f2;
    --diff-purple: #a271ff;
    --diff-border: rgba(148, 189, 255, 0.18);
    --diff-border-strong: rgba(92, 231, 242, 0.32);
    --diff-shadow: 0 30px 80px rgba(3, 8, 24, 0.46);
    --diff-radius: 28px;
    --diff-max: 1240px;
    --diff-reading: #f5f4ef;
    --diff-reading-panel: #fffefb;
    --diff-reading-text: #152135;
    --diff-reading-muted: #536175;
    --diff-reading-rule: #d8dde3;
    --diff-reading-blue: #315dc5;
    --diff-reading-cyan: #087f8d;
    --diff-toc-width: 17.5rem;
}

#diff-mode-page {
    position: relative;
    overflow-x: clip;
    color: var(--diff-text);
    background:
        radial-gradient(circle at top left, rgba(92, 231, 242, 0.15), transparent 30%),
        radial-gradient(circle at 88% 8%, rgba(162, 113, 255, 0.17), transparent 28%),
        linear-gradient(180deg, #040712 0%, #07101f 48%, #03050d 100%);
    isolation: isolate;
}

#diff-mode-page,
#diff-mode-page * {
    box-sizing: border-box;
}

#diff-mode-page::before {
    content: "";
    position: absolute;
    inset: 0;
    z-index: -2;
    pointer-events: none;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.018) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.018) 1px, transparent 1px);
    background-size: 120px 120px;
    mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.5), transparent 52%);
}

.diff-grid,
.diff-aurora {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.diff-grid {
    z-index: -1;
    opacity: 0.58;
    background-image:
        radial-gradient(circle at 10% 16%, rgba(255, 255, 255, 0.75) 0 1px, transparent 1.4px),
        radial-gradient(circle at 19% 72%, rgba(255, 255, 255, 0.68) 0 1px, transparent 1.4px),
        radial-gradient(circle at 34% 31%, rgba(92, 231, 242, 0.82) 0 1.2px, transparent 1.8px),
        radial-gradient(circle at 51% 58%, rgba(255, 255, 255, 0.72) 0 1px, transparent 1.4px),
        radial-gradient(circle at 69% 19%, rgba(162, 113, 255, 0.77) 0 1.2px, transparent 1.8px),
        radial-gradient(circle at 83% 43%, rgba(92, 231, 242, 0.8) 0 1.1px, transparent 1.7px),
        radial-gradient(circle at 92% 76%, rgba(255, 255, 255, 0.68) 0 1px, transparent 1.4px);
    animation: diff-twinkle 10s linear infinite alternate;
}

.diff-aurora {
    z-index: -1;
    filter: blur(38px);
    opacity: 0.52;
}

.diff-aurora-one {
    inset: 4% auto auto -12%;
    width: min(56vw, 720px);
    height: min(56vw, 720px);
    border-radius: 999px;
    background: radial-gradient(circle, rgba(92, 231, 242, 0.18), transparent 68%);
}

.diff-aurora-two {
    inset: auto -10% 36% auto;
    width: min(50vw, 650px);
    height: min(50vw, 650px);
    border-radius: 999px;
    background: radial-gradient(circle, rgba(162, 113, 255, 0.17), transparent 68%);
}

.diff-section {
    position: relative;
    padding: clamp(5rem, 8vw, 8rem) 1.5rem;
}

.diff-shell,
.diff-manual-shell {
    width: min(100%, var(--diff-max));
    margin: 0 auto;
}

#diff-mode-page h1,
#diff-mode-page h2,
#diff-mode-page h3,
#diff-mode-page h4,
#diff-mode-page p {
    margin-top: 0;
}

#diff-mode-page h1,
#diff-mode-page h2,
#diff-mode-page h3,
#diff-mode-page h4 {
    font-family: "Manrope", "Segoe UI", sans-serif;
    letter-spacing: -0.035em;
    text-wrap: balance;
}

#diff-mode-page p,
#diff-mode-page li,
#diff-mode-page a,
#diff-mode-page span,
#diff-mode-page strong,
#diff-mode-page dt,
#diff-mode-page dd,
#diff-mode-page summary,
#diff-mode-page code {
    font-family: "Manrope", "Segoe UI", sans-serif;
}

#diff-mode-page h1 {
    margin-bottom: 1.35rem;
    font-size: clamp(3.25rem, 7vw, 6.35rem);
    line-height: 0.93;
}

#diff-mode-page h2 {
    margin-bottom: 1.15rem;
    font-size: clamp(2.25rem, 4.5vw, 4.4rem);
    line-height: 1;
}

#diff-mode-page h3 {
    margin-bottom: 0.72rem;
    font-size: clamp(1.35rem, 2.1vw, 1.9rem);
    line-height: 1.14;
}

#diff-mode-page h4 {
    margin-bottom: 0.65rem;
    font-size: 1.05rem;
    line-height: 1.3;
}

#diff-mode-page p {
    color: var(--diff-muted);
    font-size: clamp(1rem, 1.18vw, 1.1rem);
    line-height: 1.75;
}

.diff-eyebrow,
.diff-card-kicker,
.diff-placeholder > span,
.diff-physics-item > span {
    letter-spacing: 0.2em;
    text-transform: uppercase;
}

.diff-eyebrow {
    margin-bottom: 1rem;
    color: var(--diff-cyan);
    font-size: 0.82rem;
    font-weight: 800;
}

.diff-card-kicker {
    color: rgba(237, 244, 255, 0.72);
    font-size: 0.72rem;
    font-weight: 800;
}

.diff-hero {
    padding-top: clamp(5rem, 9vw, 8rem);
    padding-bottom: clamp(3.4rem, 6vw, 5.3rem);
}

.diff-hero-grid,
.diff-linked-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.06fr) minmax(0, 0.94fr);
    gap: clamp(2.3rem, 5vw, 5rem);
    align-items: center;
}

.diff-intro {
    max-width: 45rem;
    font-size: clamp(1.08rem, 1.45vw, 1.28rem) !important;
}

.diff-button-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.9rem;
    margin-top: 2rem;
}

.diff-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 11.2rem;
    min-height: 3.45rem;
    padding: 0.9rem 1.4rem;
    border: 1px solid rgba(148, 189, 255, 0.24);
    border-radius: 999px;
    color: var(--diff-text);
    font-size: 0.94rem;
    font-weight: 800;
    line-height: 1;
    text-decoration: none;
    transition: transform 180ms ease, border-color 180ms ease, box-shadow 180ms ease, background 180ms ease;
}

.diff-button:hover,
.diff-button:focus-visible {
    transform: translateY(-2px);
    border-color: rgba(92, 231, 242, 0.55);
    box-shadow: 0 16px 42px rgba(2, 9, 27, 0.36);
}

.diff-button:focus-visible,
.diff-toc a:focus-visible,
.diff-manual a:focus-visible,
.diff-faq-list summary:focus-visible {
    outline: 3px solid rgba(92, 231, 242, 0.68);
    outline-offset: 4px;
}

.diff-button-primary {
    color: #03121d;
    background: linear-gradient(135deg, #7898ff, #5ce7f2);
}

.diff-button-secondary {
    background: rgba(10, 19, 39, 0.55);
    backdrop-filter: blur(14px);
}

.diff-visual-card,
.diff-band-inner,
.diff-difference-card,
.diff-aavso-panel,
.diff-open-source-inner,
.diff-closing-inner {
    position: relative;
    overflow: hidden;
    border: 1px solid var(--diff-border);
    border-radius: var(--diff-radius);
    background: linear-gradient(180deg, rgba(15, 25, 50, 0.86), rgba(9, 17, 35, 0.62));
    box-shadow: var(--diff-shadow);
    backdrop-filter: blur(18px);
}

.diff-visual-card::after,
.diff-difference-card::after,
.diff-aavso-panel::after,
.diff-open-source-inner::after,
.diff-closing-inner::after {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    pointer-events: none;
    background:
        linear-gradient(90deg, rgba(92, 231, 242, 0.24), rgba(162, 113, 255, 0.08) 50%, transparent 80%) top / 100% 1px no-repeat,
        radial-gradient(circle at 12% 8%, rgba(92, 231, 242, 0.06), transparent 34%);
}

.diff-hero-visual {
    display: grid;
    gap: 0.9rem;
}

.diff-visual-card {
    padding: 1rem;
}

.diff-card-kicker-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.85rem;
}

.diff-card-chip {
    padding: 0.42rem 0.68rem;
    border-radius: 999px;
    color: var(--diff-cyan);
    background: rgba(92, 231, 242, 0.11);
    font-size: 0.72rem;
    font-weight: 800;
}

.diff-visual-card img {
    display: block;
    width: 100%;
    aspect-ratio: 16 / 10;
    object-fit: cover;
    border-radius: calc(var(--diff-radius) - 12px);
}

.diff-proof-strip {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1px;
    overflow: hidden;
    border: 1px solid rgba(148, 189, 255, 0.15);
    border-radius: 18px;
    background: rgba(148, 189, 255, 0.12);
}

.diff-proof-strip span {
    padding: 0.95rem 0.85rem;
    color: rgba(237, 244, 255, 0.82);
    background: rgba(7, 14, 30, 0.88);
    font-size: 0.73rem;
    font-weight: 800;
    line-height: 1.45;
    text-align: center;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.diff-band {
    padding: 0 1.5rem;
}

.diff-band-inner {
    padding: clamp(2.5rem, 5vw, 4.1rem);
    background:
        radial-gradient(circle at top center, rgba(92, 231, 242, 0.09), transparent 36%),
        radial-gradient(circle at 78% 0%, rgba(162, 113, 255, 0.09), transparent 32%),
        linear-gradient(160deg, rgba(12, 21, 44, 0.97), rgba(7, 14, 29, 0.94));
}

.diff-band-copy {
    max-width: 61rem;
    margin: 0 auto clamp(2rem, 4vw, 3rem);
    text-align: center;
}

#diff-mode-page .diff-band-title {
    font-size: clamp(2rem, 3.4vw, 3.35rem);
}

.diff-band-intro {
    max-width: 49rem;
    margin-right: auto;
    margin-bottom: 0;
    margin-left: auto;
}

.diff-pulse-demo {
    display: grid;
    grid-template-columns: minmax(14rem, 0.72fr) 3rem minmax(0, 1.28fr);
    gap: 1rem;
    align-items: stretch;
}

.diff-pulse-star-panel,
.diff-pulse-curve-panel {
    position: relative;
    min-width: 0;
    padding: 1rem;
    border: 1px solid rgba(148, 189, 255, 0.14);
    border-radius: 22px;
    background:
        linear-gradient(180deg, rgba(9, 20, 42, 0.78), rgba(5, 12, 27, 0.68)),
        rgba(5, 12, 27, 0.62);
}

.diff-pulse-label {
    display: block;
    color: rgba(237, 244, 255, 0.72);
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

.diff-pulse-star-svg,
.diff-pulse-curve-svg {
    display: block;
    width: 100%;
    height: 14.5rem;
}

.diff-pulse-star-svg text {
    fill: rgba(237, 244, 255, 0.54);
    font-family: "Manrope", "Segoe UI", sans-serif;
    font-size: 10px;
    letter-spacing: 0.04em;
}

.diff-pulse-star-svg .diff-pulse-state {
    fill: var(--diff-cyan);
    font-size: 11px;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.diff-pulse-link {
    display: grid;
    place-items: center;
}

.diff-pulse-link::before {
    content: "";
    width: 100%;
    height: 1px;
    background: linear-gradient(90deg, rgba(92, 231, 242, 0.12), rgba(92, 231, 242, 0.7), rgba(162, 113, 255, 0.24));
}

.diff-pulse-link span {
    position: absolute;
    width: 0.48rem;
    height: 0.48rem;
    border-radius: 999px;
    background: var(--diff-cyan);
    box-shadow: 0 0 14px rgba(92, 231, 242, 0.8);
    animation: diff-signal-travel 2s ease-in-out infinite;
}

.diff-curve-grid line {
    stroke: rgba(148, 189, 255, 0.11);
    stroke-width: 1;
}

.diff-pulse-curve-ghost,
.diff-pulse-curve-live {
    fill: none;
    vector-effect: non-scaling-stroke;
}

.diff-pulse-curve-ghost {
    stroke: rgba(148, 189, 255, 0.16);
    stroke-width: 3;
}

.diff-pulse-curve-live {
    stroke: url("#diff-curve-gradient");
    stroke-width: 4;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-dasharray: 1;
    stroke-dashoffset: 1;
}

.diff-pulse-marker {
    stroke: var(--diff-cyan);
    stroke-width: 3;
    vector-effect: non-scaling-stroke;
    filter: drop-shadow(0 0 7px rgba(92, 231, 242, 0.88));
}

.diff-curve-axis-label {
    fill: rgba(237, 244, 255, 0.5);
    font-family: "Manrope", "Segoe UI", sans-serif;
    font-size: 11px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.diff-section-heading {
    max-width: 54rem;
    margin-bottom: clamp(2.2rem, 4vw, 3.5rem);
}

.diff-section-heading > p:last-child {
    max-width: 46rem;
}

.diff-difference-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1.15rem;
}

.diff-difference-grid-compact {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.diff-difference-card {
    min-height: 21rem;
    padding: clamp(1.7rem, 3vw, 2.4rem);
}

.diff-difference-card-wide {
    display: grid;
    grid-column: 1 / -1;
    grid-template-columns: minmax(0, 1.1fr) minmax(18rem, 0.9fr);
    gap: 2rem;
    min-height: auto;
    align-items: center;
}

.diff-difference-card h3 {
    margin-top: 0.8rem !important;
}

.diff-difference-card-compact {
    min-height: 13rem;
}

.diff-difference-card-compact p {
    margin-bottom: 0;
    font-size: 0.98rem !important;
}

.diff-difference-note {
    max-width: 54rem;
    margin: 1.5rem 0 0 !important;
    color: rgba(237, 244, 255, 0.76) !important;
    font-size: 0.96rem !important;
}

.diff-example {
    padding: 1.3rem;
    border-left: 2px solid var(--diff-cyan);
    background: rgba(92, 231, 242, 0.055);
}

.diff-example strong {
    color: var(--diff-cyan);
    font-size: 0.76rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.diff-example p {
    margin: 0.55rem 0 0;
    color: rgba(237, 244, 255, 0.88) !important;
    font-size: 0.98rem !important;
}

.diff-linked {
    padding-top: clamp(3rem, 6vw, 6rem);
}

.diff-marketing-list {
    display: grid;
    gap: 0.8rem;
    margin: 1.5rem 0 0;
    padding: 0;
    list-style: none;
}

.diff-marketing-list li {
    position: relative;
    padding-left: 1.55rem;
    color: rgba(237, 244, 255, 0.88);
    line-height: 1.65;
}

.diff-marketing-list li::before {
    content: "";
    position: absolute;
    top: 0.68rem;
    left: 0;
    width: 0.54rem;
    height: 0.54rem;
    border-radius: 999px;
    background: var(--diff-cyan);
    box-shadow: 0 0 16px rgba(92, 231, 242, 0.55);
}

.diff-placeholder {
    display: flex;
    min-height: 19rem;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    padding: clamp(1.7rem, 4vw, 2.6rem);
}

.diff-placeholder-dark {
    border: 1px dashed rgba(92, 231, 242, 0.44);
    border-radius: var(--diff-radius);
    background:
        linear-gradient(135deg, rgba(92, 231, 242, 0.07), rgba(162, 113, 255, 0.06)),
        rgba(6, 14, 30, 0.7);
}

.diff-placeholder > span {
    margin-bottom: 0.7rem;
    color: var(--diff-cyan);
    font-size: 0.7rem;
    font-weight: 800;
}

.diff-placeholder > strong {
    max-width: 34rem;
    color: var(--diff-text);
    font-size: clamp(1.2rem, 2vw, 1.65rem);
    line-height: 1.35;
}

.diff-placeholder > p {
    max-width: 34rem;
    margin: 0.7rem 0 0;
    font-size: 0.92rem !important;
}

.diff-physics {
    padding-top: clamp(3rem, 6vw, 6rem);
}

.diff-physics-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    border-top: 1px solid var(--diff-border);
    border-bottom: 1px solid var(--diff-border);
}

.diff-physics-item {
    min-height: 18rem;
    padding: 2rem 1.7rem 1.8rem;
    border-right: 1px solid var(--diff-border);
}

.diff-physics-item:last-child {
    border-right: 0;
}

.diff-physics-item > span {
    display: block;
    margin-bottom: 2.8rem;
    color: var(--diff-cyan);
    font-size: 0.72rem;
    font-weight: 800;
}

.diff-physics-item p {
    margin-bottom: 0;
}

.diff-aavso {
    padding-top: clamp(3.5rem, 6vw, 6rem);
}

.diff-aavso-panel {
    display: grid;
    grid-template-columns: minmax(0, 1.25fr) minmax(18rem, 0.75fr);
    gap: clamp(2rem, 5vw, 4rem);
    align-items: center;
    padding: clamp(2rem, 4vw, 3.4rem);
    border-color: var(--diff-border-strong);
    background:
        radial-gradient(circle at 90% 10%, rgba(92, 231, 242, 0.12), transparent 34%),
        linear-gradient(150deg, rgba(14, 28, 56, 0.98), rgba(7, 15, 31, 0.96));
}

.diff-aavso-steps {
    display: grid;
    gap: 0;
    margin: 0;
    padding: 0;
    list-style: none;
}

.diff-aavso-steps li {
    display: grid;
    grid-template-columns: 2.4rem 1fr;
    gap: 0.85rem;
    align-items: center;
    padding: 0.92rem 0;
    border-bottom: 1px solid rgba(148, 189, 255, 0.14);
    color: var(--diff-text);
    font-weight: 700;
}

.diff-aavso-steps li:last-child {
    border-bottom: 0;
}

.diff-aavso-steps span {
    display: grid;
    width: 2.25rem;
    height: 2.25rem;
    place-items: center;
    border: 1px solid rgba(92, 231, 242, 0.32);
    border-radius: 999px;
    color: var(--diff-cyan);
    background: rgba(92, 231, 242, 0.08);
    font-size: 0.78rem;
}

.diff-open-source {
    padding-top: 0;
}

.diff-open-source-inner {
    padding: clamp(2.2rem, 5vw, 4rem);
    text-align: center;
}

.diff-open-source-inner > p:not(.diff-eyebrow) {
    max-width: 50rem;
    margin-right: auto;
    margin-left: auto;
}

.diff-open-source-inner .diff-button {
    margin-top: 1.1rem;
}

/* Long-form manual: intentionally editorial, flat, and separate from marketing cards. */
.diff-manual {
    position: relative;
    padding: clamp(5rem, 8vw, 8rem) 1.5rem clamp(6rem, 10vw, 10rem);
    color: var(--diff-reading-text);
    background:
        linear-gradient(90deg, rgba(49, 93, 197, 0.035) 1px, transparent 1px),
        var(--diff-reading);
    background-size: 160px 100%;
}

.diff-manual,
.diff-manual * {
    scroll-margin-top: 1.4rem;
}

#diff-mode-page .diff-manual h2,
#diff-mode-page .diff-manual h3,
#diff-mode-page .diff-manual h4 {
    color: var(--diff-reading-text);
}

#diff-mode-page .diff-manual h2 {
    font-size: clamp(2.3rem, 4.5vw, 4.25rem);
}

#diff-mode-page .diff-manual h3 {
    font-size: clamp(1.45rem, 2.2vw, 2rem);
}

#diff-mode-page .diff-manual h4 {
    font-size: 1.04rem;
    letter-spacing: -0.015em;
}

#diff-mode-page .diff-manual p,
#diff-mode-page .diff-manual li,
#diff-mode-page .diff-manual dd {
    color: var(--diff-reading-muted);
    font-size: 1rem;
    line-height: 1.78;
}

#diff-mode-page .diff-manual strong,
#diff-mode-page .diff-manual dt {
    color: var(--diff-reading-text);
}

.diff-manual-intro {
    max-width: 53rem;
    margin-bottom: clamp(3rem, 5vw, 4.5rem);
}

.diff-manual-intro > p:last-child,
.diff-science-intro > p:last-child {
    max-width: 48rem;
    font-size: 1.08rem !important;
}

.diff-manual-kicker {
    margin-bottom: 0.9rem !important;
    color: var(--diff-reading-cyan) !important;
    font-size: 0.76rem !important;
    font-weight: 800;
    letter-spacing: 0.19em;
    text-transform: uppercase;
}

.diff-manual-layout {
    display: grid;
    grid-template-columns: var(--diff-toc-width) minmax(0, 1fr);
    gap: clamp(2rem, 5vw, 5rem);
    align-items: start;
}

.diff-toc {
    position: sticky;
    top: 1.25rem;
    max-height: calc(100vh - 2.5rem);
    overflow-y: auto;
    padding: 0.9rem 0;
    border-top: 1px solid var(--diff-reading-rule);
    border-bottom: 1px solid var(--diff-reading-rule);
}

.diff-toc p {
    margin: 0 0 0.55rem !important;
    padding: 0 0.65rem;
    color: var(--diff-reading-cyan) !important;
    font-size: 0.7rem !important;
    font-weight: 800;
    letter-spacing: 0.17em;
    text-transform: uppercase;
}

.diff-toc a {
    display: block;
    padding: 0.42rem 0.65rem;
    border-left: 2px solid transparent;
    color: #5c6878;
    font-size: 0.84rem;
    font-weight: 650;
    line-height: 1.35;
    text-decoration: none;
    transition: color 160ms ease, border-color 160ms ease, background 160ms ease;
}

.diff-toc a:hover,
.diff-toc a.is-active {
    border-left-color: var(--diff-reading-cyan);
    color: var(--diff-reading-text);
    background: rgba(8, 127, 141, 0.055);
}

.diff-lessons {
    min-width: 0;
}

.diff-lesson,
.diff-science-chapter {
    padding: 0 0 clamp(3.4rem, 6vw, 5.4rem);
    margin-bottom: clamp(3.4rem, 6vw, 5.4rem);
    border-bottom: 1px solid var(--diff-reading-rule);
}

.diff-lesson-head {
    display: grid;
    grid-template-columns: 2.7rem minmax(0, 1fr);
    gap: 0.9rem;
    align-items: baseline;
    margin-bottom: 1.35rem;
}

.diff-lesson-head > span {
    color: var(--diff-reading-cyan);
    font-family: "Space Grotesk", "Segoe UI", sans-serif;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.14em;
}

.diff-lesson-head h3 {
    margin: 0 !important;
}

.diff-action-list,
.diff-do-list {
    display: grid;
    gap: 0.55rem;
    margin: 1rem 0 1.35rem;
    padding-left: 1.35rem;
}

.diff-action-list li::marker {
    color: var(--diff-reading-blue);
    font-weight: 800;
}

.diff-do-list li::marker {
    color: var(--diff-reading-cyan);
}

.diff-manual a {
    color: var(--diff-reading-blue);
    text-underline-offset: 0.18em;
}

.diff-manual-note,
.diff-alternative {
    margin: 1.5rem 0;
    padding: 1rem 0 1rem 1.25rem;
    border-left: 3px solid var(--diff-reading-cyan);
}

.diff-manual-note-important {
    border-left-color: var(--diff-reading-blue);
}

.diff-manual-note > strong,
.diff-alternative > strong {
    display: block;
    margin-bottom: 0.32rem;
    font-size: 0.88rem;
}

.diff-manual-note p,
.diff-alternative p {
    margin: 0;
    font-size: 0.94rem !important;
}

.diff-placeholder-light {
    min-height: 13rem;
    margin: 1.8rem 0;
    border: 1px dashed #aeb8c5;
    border-radius: 8px;
    background:
        linear-gradient(135deg, rgba(49, 93, 197, 0.045), rgba(8, 127, 141, 0.04)),
        rgba(255, 255, 255, 0.45);
}

.diff-placeholder-light > span {
    color: var(--diff-reading-cyan);
}

.diff-placeholder-light > strong {
    color: var(--diff-reading-text);
    font-size: 1.15rem;
}

.diff-placeholder-light > p {
    color: var(--diff-reading-muted) !important;
}

.diff-control-list,
.diff-compact-settings {
    margin: 1.2rem 0 1.6rem;
}

.diff-control-list > div,
.diff-compact-settings > div {
    display: grid;
    grid-template-columns: minmax(10rem, 0.34fr) minmax(0, 0.66fr);
    gap: 1.3rem;
    padding: 0.9rem 0;
    border-top: 1px solid var(--diff-reading-rule);
}

.diff-control-list > div:last-child,
.diff-compact-settings > div:last-child {
    border-bottom: 1px solid var(--diff-reading-rule);
}

.diff-control-list dt,
.diff-compact-settings dt {
    font-size: 0.9rem;
    font-weight: 800;
}

.diff-control-list dd,
.diff-compact-settings dd {
    margin: 0;
    font-size: 0.94rem !important;
}

.diff-two-column {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 2rem;
    margin: 1.4rem 0;
}

.diff-two-column > div {
    padding-top: 1rem;
    border-top: 2px solid var(--diff-reading-rule);
}

.diff-key-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin-top: 1.3rem;
}

.diff-key-row span {
    padding: 0.55rem 0.72rem;
    border: 1px solid #cbd2da;
    border-radius: 5px;
    color: #415168;
    background: rgba(255, 255, 255, 0.52);
    font-size: 0.82rem;
    font-weight: 700;
}

.diff-equation-light {
    display: grid;
    gap: 0.55rem;
    margin: 1.3rem 0;
    padding: 1rem 1.15rem;
    border-left: 3px solid var(--diff-reading-blue);
    background: #e9edf5;
}

.diff-equation-light code {
    overflow-wrap: anywhere;
    color: #1f355d;
    font-family: "Space Grotesk", Consolas, monospace !important;
    font-size: 0.95rem;
    line-height: 1.55;
}

.diff-setting-section {
    padding: 1.4rem 0;
    border-top: 1px solid var(--diff-reading-rule);
}

.diff-setting-section:last-child {
    border-bottom: 1px solid var(--diff-reading-rule);
}

.diff-setting-section p {
    margin-bottom: 0;
}

.diff-faq-list {
    display: grid;
    border-top: 1px solid var(--diff-reading-rule);
}

.diff-faq-list details {
    border-bottom: 1px solid var(--diff-reading-rule);
}

.diff-faq-list summary {
    padding: 1rem 2rem 1rem 0;
    color: var(--diff-reading-text);
    font-size: 0.94rem;
    font-weight: 800;
    cursor: pointer;
}

.diff-faq-list details p {
    max-width: 47rem;
    padding: 0 0 1rem;
    margin: 0;
    font-size: 0.94rem !important;
}

.diff-science-intro {
    padding: clamp(2.8rem, 5vw, 4.5rem) 0 clamp(3.2rem, 6vw, 5.5rem);
    scroll-margin-top: 1.4rem;
}

.diff-science-intro::before {
    content: "";
    display: block;
    width: 4rem;
    height: 3px;
    margin-bottom: 2rem;
    background: linear-gradient(90deg, var(--diff-reading-blue), var(--diff-reading-cyan));
}

.diff-science-chapter h3 {
    margin-bottom: 1.2rem !important;
}

.diff-quality-list {
    margin: 1.3rem 0;
    border-top: 1px solid var(--diff-reading-rule);
}

.diff-quality-list p {
    margin: 0 !important;
    padding: 0.72rem 0;
    border-bottom: 1px solid var(--diff-reading-rule);
    font-size: 0.93rem !important;
}

.diff-closing {
    background: var(--diff-bg-deep);
}

.diff-closing-inner {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 2rem;
    align-items: center;
    padding: clamp(2rem, 4vw, 3.2rem);
    border-color: var(--diff-border-strong);
}

.diff-closing-inner p:not(.diff-eyebrow) {
    max-width: 45rem;
    margin-bottom: 0;
}

.diff-reveal {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 680ms ease, transform 680ms ease;
}

.diff-reveal.is-visible {
    opacity: 1;
    transform: none;
}

@keyframes diff-twinkle {
    from {
        transform: translateY(0);
        opacity: 0.45;
    }
    to {
        transform: translateY(-10px);
        opacity: 0.68;
    }
}

@keyframes diff-signal-travel {
    0%,
    100% {
        transform: translateX(-1rem);
        opacity: 0.35;
    }
    50% {
        transform: translateX(1rem);
        opacity: 1;
    }
}

@media (max-width: 1080px) {
    .diff-hero-grid,
    .diff-linked-grid,
    .diff-aavso-panel,
    .diff-closing-inner {
        grid-template-columns: 1fr;
    }

    .diff-hero-visual {
        max-width: 52rem;
    }

    .diff-pulse-demo {
        grid-template-columns: minmax(14rem, 0.7fr) minmax(0, 1.3fr);
    }

    .diff-pulse-link {
        display: none;
    }

    .diff-manual-layout {
        grid-template-columns: 1fr;
    }

    .diff-toc {
        position: relative;
        top: 0;
        max-height: none;
        columns: 2;
        column-gap: 1rem;
    }

    .diff-toc p {
        column-span: all;
    }

    .diff-toc a {
        break-inside: avoid;
    }
}

@media (max-width: 780px) {
    .diff-section,
    .diff-band,
    .diff-manual {
        padding-right: 1rem;
        padding-left: 1rem;
    }

    #diff-mode-page h1 {
        font-size: clamp(3rem, 15vw, 4.7rem);
    }

    #diff-mode-page h2 {
        font-size: clamp(2rem, 10vw, 3rem);
    }

    .diff-difference-grid,
    .diff-difference-grid-compact,
    .diff-difference-card-wide,
    .diff-physics-grid,
    .diff-two-column {
        grid-template-columns: 1fr;
    }

    .diff-pulse-demo {
        grid-template-columns: 1fr;
    }

    .diff-pulse-star-svg,
    .diff-pulse-curve-svg {
        height: 12rem;
    }

    .diff-difference-card-wide {
        gap: 1rem;
    }

    .diff-physics-grid {
        border-bottom: 0;
    }

    .diff-physics-item {
        min-height: auto;
        padding: 1.6rem 0;
        border-right: 0;
        border-bottom: 1px solid var(--diff-border);
    }

    .diff-physics-item > span {
        margin-bottom: 1rem;
    }

    .diff-proof-strip {
        grid-template-columns: 1fr;
    }

    .diff-visual-card,
    .diff-band-inner,
    .diff-difference-card,
    .diff-aavso-panel,
    .diff-open-source-inner,
    .diff-closing-inner,
    .diff-placeholder-dark {
        border-radius: 21px;
    }

    .diff-toc {
        columns: 1;
    }

    .diff-control-list > div,
    .diff-compact-settings > div {
        grid-template-columns: 1fr;
        gap: 0.3rem;
    }

    .diff-lesson-head {
        grid-template-columns: 2rem minmax(0, 1fr);
    }
}

@media (max-width: 480px) {
    .diff-button,
    .diff-button-row {
        width: 100%;
    }

    .diff-card-kicker-row {
        align-items: flex-start;
        flex-direction: column;
    }

    .diff-key-row {
        display: grid;
    }

    .diff-key-row span {
        width: 100%;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto !important;
    }

    .diff-grid {
        animation: none;
    }

    .diff-pulse-link span {
        animation: none;
    }

    .diff-pulse-curve-live {
        stroke-dashoffset: 0;
        animation: none;
    }

    .diff-reveal {
        opacity: 1;
        transform: none;
        transition: none;
    }

    .diff-button,
    .diff-toc a {
        transition: none;
    }
}