/* Automatic local routing research note */
:root {
    color-scheme: light dark;
    --background: #fff;
    --surface: #f6f6f4;
    --surface-strong: #ededeb;
    --text: #111;
    --text-soft: #555;
    --text-faint: #767676;
    --line: #dededb;
    --line-strong: #aaa;
    --progress: #e85d04;
    --code: #20201e;
    --code-text: #f0f0ec;
    --sans: "Helvetica Neue", Helvetica, Arial, sans-serif;
    --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 3rem;
    font-size: clamp(16px, 15px + 0.3vw, 19px);
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    padding: 3rem 1.5rem 0;
    background: var(--background);
    color: var(--text);
    font-family: var(--sans);
    font-weight: 300;
    line-height: 1.65;
    text-rendering: optimizeLegibility;
}

::selection {
    background: var(--surface-strong);
}

a {
    color: var(--text);
    text-decoration-color: currentColor;
    text-decoration-thickness: 1px;
    text-underline-offset: 0.18em;
}

a:hover {
    opacity: 0.7;
}

.reading-progress {
    position: fixed;
    inset: 0 0 auto;
    z-index: 10;
    height: 2px;
    background: transparent;
}

.reading-progress span {
    display: block;
    width: 0;
    height: 100%;
    background: var(--progress);
}

.page-shell {
    width: min(100%, 42rem);
    margin: 0 auto;
}

.site-nav {
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.site-nav a {
    position: relative;
    padding-bottom: 0.125rem;
    color: var(--text-soft);
    text-decoration: none;
}

.site-nav a::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--text);
    transition: width 0.3s ease;
}

.site-nav a:hover {
    color: var(--text);
    opacity: 1;
}

.site-nav a:hover::after {
    width: 100%;
}

.article-header {
    margin-bottom: 2rem;
}

.article-divider {
    margin: 0 0 2rem;
    border: 0;
    border-top: 1px solid var(--line);
}

.section-number,
.note-label,
.diagram-label,
.equation-label {
    margin: 0 0 0.75rem;
    color: var(--text-faint);
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.08em;
    line-height: 1.3;
    text-transform: uppercase;
}

h1,
h2,
h3 {
    margin-top: 0;
    color: var(--text);
    font-weight: 300;
    letter-spacing: -0.025em;
}

h1 {
    margin-bottom: 0.5rem;
    font-size: clamp(1.5rem, 1.3rem + 1vw, 1.9rem);
    line-height: 1.35;
}

h1 em {
    color: inherit;
    font-style: italic;
    font-weight: 300;
}

.dek {
    margin: 0;
    color: var(--text-soft);
    font-size: 1rem;
    line-height: 1.6;
}

.article-body {
    min-width: 0;
}

.router-hero {
    width: min(36rem, calc(100vw - 2rem));
    margin: 0 auto 3rem;
}

.router-hero canvas {
    display: block;
    width: 100%;
    height: auto;
    background: var(--background);
    image-rendering: pixelated;
    image-rendering: crisp-edges;
}

.article-body p {
    margin: 1.35rem 0;
}

.article-body .lead {
    margin-top: 0;
    color: var(--text);
}

.article-body section {
    position: relative;
    margin-top: 4rem;
}

.section-number {
    margin-bottom: 0.8rem;
    font-family: var(--mono);
}

h2 {
    margin-bottom: 1.8rem;
    font-size: clamp(1.75rem, 5vw, 2.5rem);
    line-height: 1.15;
}

h3 {
    margin: 3.5rem 0 1rem;
    font-size: clamp(1.35rem, 4vw, 1.75rem);
    line-height: 1.25;
}

code {
    padding: 0.12em 0.3em;
    border-radius: 0.2rem;
    background: var(--surface-strong);
    font-family: var(--mono);
    font-size: 0.8em;
}

blockquote {
    margin: 2.5rem 0;
    padding: 0.2rem 0 0.2rem 1.25rem;
    border-left: 2px solid var(--line-strong);
    color: var(--text-soft);
    font-size: 1.2rem;
    line-height: 1.55;
}

blockquote p {
    margin: 0 !important;
}

.note {
    margin: 2.5rem 0;
    padding: 1.25rem 1.35rem;
    border: 1px solid var(--line);
    border-left: 3px solid var(--line-strong);
    background: var(--surface);
}

.note-label {
    margin: 0 0 0.35rem !important;
    color: var(--text);
}

.note p:last-child {
    margin: 0;
}

.roles {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    margin: 2.5rem 0;
    border-top: 1px solid var(--line);
}

.roles > div {
    padding: 1.25rem 1rem;
    border-bottom: 1px solid var(--line);
}

.roles > div:nth-child(odd) {
    border-right: 1px solid var(--line);
}

.role-name {
    display: flex;
    gap: 0.55rem;
    align-items: center;
    margin: 0 !important;
    font-size: 0.88rem;
    font-weight: 400;
}

.role-description {
    margin: 0.45rem 0 0 1.1rem !important;
    color: var(--text-soft);
    font-size: 0.88rem;
    line-height: 1.45;
}

.role-dot {
    flex: 0 0 auto;
    width: 0.5rem;
    height: 0.5rem;
    border-radius: 50%;
    background: var(--line-strong);
}

.diagram {
    width: min(52rem, calc(100vw - 2rem));
    margin: 3rem 0 3rem clamp(-5rem, -7vw, 0rem);
    padding: clamp(1.1rem, 4vw, 2.25rem);
    border: 1px solid var(--line);
    background: var(--surface);
}

.diagram-label {
    margin-bottom: 1.75rem;
}

.diagram figcaption {
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--line);
    color: var(--text-soft);
    font-size: 0.78rem;
    line-height: 1.5;
}

.diagram figcaption span {
    color: var(--text);
    font-weight: 400;
    text-transform: uppercase;
}

.shadow-flow,
.decision-flow {
    display: grid;
    justify-items: center;
}

.flow-node,
.decision-node {
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    min-width: 10rem;
    min-height: 3.7rem;
    padding: 0.7rem 0.9rem;
    border: 1px solid var(--line-strong);
    background: var(--background);
    text-align: center;
}

.accent-node,
.decision-node {
    border-color: var(--line-strong);
    background: var(--surface-strong);
}

.flow-node strong,
.decision-node strong {
    font-size: 0.72rem;
    font-weight: 400;
    line-height: 1.3;
}

.flow-node small,
.decision-node small {
    margin-top: 0.25rem;
    color: var(--text-faint);
    font-size: 0.6rem;
    line-height: 1.35;
}

.node-index {
    position: absolute;
    top: -0.55rem;
    left: -0.55rem;
    display: grid;
    place-items: center;
    width: 1.15rem;
    height: 1.15rem;
    border-radius: 50%;
    background: var(--text);
    color: var(--background);
    font-family: var(--mono);
    font-size: 0.55rem;
}

.flow-split {
    position: relative;
    width: 52%;
    height: 2rem;
    border-bottom: 1px solid var(--line-strong);
}

.flow-split::before {
    content: "";
    position: absolute;
    left: 50%;
    height: 100%;
    border-left: 1px solid var(--line-strong);
}

.flow-split span {
    position: absolute;
    bottom: -2rem;
    height: 2rem;
    border-left: 1px solid var(--line-strong);
}

.flow-split span:first-child {
    left: 0;
}

.flow-split span:last-child {
    right: 0;
}

.parallel-paths {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: clamp(2rem, 8vw, 5rem);
    width: 100%;
    margin-top: 2rem;
}

.path,
.branch {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.path .flow-node,
.branch .flow-node {
    width: min(100%, 14rem);
}

.vertical-arrow {
    color: var(--text-faint);
    font-family: var(--mono);
    line-height: 1;
}

.code-card {
    margin: 2.5rem 0;
    border-radius: 0.25rem;
    background: var(--code);
    overflow: hidden;
}

.code-header {
    display: flex;
    justify-content: space-between;
    padding: 0.65rem 0.9rem;
    border-bottom: 1px solid #444;
    color: #aaa;
    font-family: var(--mono);
    font-size: 0.62rem;
}

.code-card pre {
    margin: 0;
    padding: 1.25rem;
    overflow-x: auto;
    color: var(--code-text);
    font-family: var(--mono);
    font-size: 0.72rem;
    line-height: 1.7;
}

.code-card code {
    padding: 0;
    background: none;
    font-size: inherit;
}

.token-key,
.token-value {
    color: var(--code-text);
}

.token-key {
    color: var(--code-text);
}

.token-value {
    opacity: 0.8;
}

.check-list {
    margin: 2rem 0;
    padding: 0;
    list-style: none;
}

.check-list li {
    position: relative;
    padding: 0.65rem 0 0.65rem 1.6rem;
    border-bottom: 1px solid var(--line);
}

.check-list li:first-child {
    border-top: 1px solid var(--line);
}

.check-list li::before {
    content: "✓";
    position: absolute;
    left: 0.15rem;
    color: var(--text-faint);
    font-weight: 400;
}

.equation {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 9rem;
    margin: 2.5rem 0;
    padding: 1.5rem;
    border-block: 1px solid var(--line);
    font-size: clamp(1.35rem, 4vw, 2rem);
    text-align: center;
}

.equation-label {
    margin-bottom: 1.1rem;
}

.fraction {
    display: inline-flex;
    flex-direction: column;
    margin-inline: 0.25rem;
    vertical-align: middle;
    font-size: 0.8em;
}

.fraction > span:first-child {
    padding: 0 0.35rem 0.15rem;
    border-bottom: 1px solid currentColor;
}

.fraction > span:last-child {
    padding-top: 0.15rem;
}

.number-strip {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    margin: 2.5rem 0;
    border-block: 1px solid var(--line);
}

.number-strip div {
    padding: 1.25rem 0.8rem;
    text-align: center;
}

.number-strip div + div {
    border-left: 1px solid var(--line);
}

.number-strip strong {
    display: block;
    color: var(--text);
    font-size: 1.7rem;
    font-weight: 300;
    letter-spacing: -0.03em;
}

.number-strip span {
    display: block;
    margin-top: 0.35rem;
    color: var(--text-faint);
    font-size: 0.65rem;
    line-height: 1.35;
}

.flow-node.wide {
    width: min(100%, 24rem);
}

.decision-branches {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: clamp(2rem, 8vw, 5rem);
    width: 100%;
    margin-top: 1rem;
}

.branch-label {
    color: var(--text-faint);
    font-family: var(--mono);
    font-size: 0.62rem;
}

.model-stack {
    margin: 2.5rem 0;
    border-top: 1px solid var(--line);
}

.model-stack div {
    display: flex;
    justify-content: space-between;
    gap: 1.5rem;
    align-items: baseline;
    padding: 0.8rem 0;
    border-bottom: 1px solid var(--line);
}

.model-stack span {
    color: var(--text-soft);
    font-size: 0.82rem;
}

.model-stack code {
    text-align: right;
}

.table-wrap {
    width: min(52rem, calc(100vw - 2rem));
    margin: 2.5rem 0 2.5rem clamp(-5rem, -7vw, 0rem);
    overflow-x: auto;
    border-block: 1px solid var(--line);
}

table {
    width: 100%;
    min-width: 44rem;
    border-collapse: collapse;
    font-size: 0.75rem;
    text-align: left;
}

caption {
    padding: 0.8rem;
    color: var(--text-soft);
    text-align: left;
}

th,
td {
    padding: 0.8rem;
    border-top: 1px solid var(--line);
}

th {
    color: var(--text-soft);
    font-weight: 400;
}

.verdict {
    color: var(--text);
    font-weight: 400;
}

.metric-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    margin: 2.5rem 0;
    border-top: 1px solid var(--line);
}

.metric-grid > div {
    display: flex;
    flex-direction: column;
    padding: 1rem;
    border-bottom: 1px solid var(--line);
}

.metric-grid > div:nth-child(odd) {
    border-right: 1px solid var(--line);
}

.metric-grid span,
.metric-grid small {
    color: var(--text-faint);
    font-size: 0.62rem;
    line-height: 1.35;
}

.metric-grid strong {
    margin: 0.2rem 0;
    color: var(--text);
    font-size: 1.35rem;
    font-weight: 300;
}

.proof-card {
    margin: 2.5rem 0;
    border: 1px solid var(--line);
}

.proof-heading {
    display: flex;
    gap: 0.8rem;
    align-items: center;
    padding: 1.1rem;
    background: var(--surface);
}

.proof-heading p {
    margin: 0;
    color: var(--text-faint);
    font-size: 0.72rem;
    text-transform: uppercase;
}

.proof-heading strong {
    font-weight: 400;
}

.status-light {
    flex: 0 0 auto;
    width: 0.65rem;
    height: 0.65rem;
    border-radius: 50%;
    background: var(--text);
}

.proof-stats {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.proof-stats div {
    display: flex;
    flex-direction: column;
    padding: 0.8rem;
    border-top: 1px solid var(--line);
}

.proof-stats div:not(:nth-child(3n)) {
    border-right: 1px solid var(--line);
}

.proof-stats span {
    color: var(--text-faint);
    font-size: 0.58rem;
}

.proof-stats strong {
    font-family: var(--mono);
    font-size: 0.72rem;
    font-weight: 400;
}

.limitations-list {
    margin: 2rem 0;
    padding: 0;
    list-style: none;
}

.limitations-list li {
    display: grid;
    grid-template-columns: 12rem 1fr;
    gap: 1rem;
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--line);
}

.limitations-list li:first-child {
    border-top: 1px solid var(--line);
}

.limitations-list strong {
    color: var(--text);
    font-size: 0.85rem;
    font-weight: 400;
}

.limitations-list span {
    color: var(--text-soft);
    font-size: 0.85rem;
}

.closing-quote {
    margin-top: 3.5rem;
    color: var(--text);
    font-size: clamp(1.3rem, 4vw, 1.8rem);
}

.loop-statement {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
    justify-content: center;
    margin: 2.5rem 0;
    padding: 1.5rem 0;
    font-size: 0.85rem;
}

.loop-statement i {
    color: var(--text-faint);
    font-family: var(--mono);
    font-style: normal;
}

.site-footer {
    display: flex;
    justify-content: flex-end;
    gap: 2rem;
    margin-top: 6rem;
    padding: 2rem 0 3rem;
    color: var(--text-soft);
    font-size: 0.8rem;
}

@media (prefers-color-scheme: dark) {
    :root {
        --background: #212121;
        --surface: #292927;
        --surface-strong: #343432;
        --text: #e5e5e5;
        --text-soft: #b3b3b3;
        --text-faint: #999;
        --line: #3c3c3a;
        --line-strong: #666;
        --progress: #ff7a1a;
        --code: #171715;
        --code-text: #ededeb;
    }
}

@media (max-width: 720px) {
    .reading-progress {
        display: none;
    }

    body {
        padding: 2rem 1rem 0;
    }

    .site-nav {
        margin-bottom: 1rem;
    }

    .diagram,
    .table-wrap,
    .router-hero {
        width: calc(100vw - 2rem);
        margin-left: 0;
    }

    .router-hero {
        margin-bottom: 2rem;
    }

    .roles {
        grid-template-columns: 1fr;
    }

    .roles > div:nth-child(odd) {
        border-right: 0;
    }

    .parallel-paths,
    .decision-branches {
        gap: 1rem;
    }

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

    .number-strip div + div {
        border-top: 1px solid var(--line);
        border-left: 0;
    }

    .proof-stats {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .proof-stats div:nth-child(n) {
        border-right: 0;
    }

    .proof-stats div:nth-child(odd) {
        border-right: 1px solid var(--line);
    }

    .limitations-list li {
        grid-template-columns: 1fr;
        gap: 0.25rem;
    }

    .site-footer {
        flex-direction: column;
        gap: 0.75rem;
    }
}

@media (max-width: 480px) {
    .parallel-paths,
    .decision-branches {
        grid-template-columns: 1fr;
    }

    .flow-split {
        display: none;
    }

    .parallel-paths {
        margin-top: 1rem;
    }

    .model-stack div {
        display: grid;
        gap: 0.3rem;
    }

    .model-stack code {
        width: max-content;
        max-width: 100%;
        overflow-wrap: anywhere;
        text-align: left;
    }
}

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