/* ── Sum & Carry — shared styles for the static pages (privacy, terms, 404).
   Token values are kept in step with the app in index.html. ── */

:root,
:root[data-theme="dark"] {
    --bg: #0f1115;
    --surface: #191c24;
    --surface-raised: #1e222c;
    --hairline: rgba(255, 255, 255, 0.09);
    --text: #f0f2f5;
    --text-secondary: #a8b0bd;
    --text-muted: #838c9c;
    --accent: #60a5fa;
    --accent-subtle: rgba(96, 165, 250, 0.14);
    --btn-bg: #60a5fa;
    --btn-fg: #0b0d12;
    --btn-bg-hover: #93c5fd;
    --result: #34d399;
    --negative: #fca5a5;
}

:root[data-theme="light"] {
    --bg: #f4f6f9;
    --surface: #ffffff;
    --surface-raised: #eef1f6;
    --hairline: rgba(15, 23, 42, 0.12);
    --text: #111520;
    --text-secondary: #4a5261;
    --text-muted: #5f6878;
    --accent: #1d4ed8;
    --accent-subtle: rgba(29, 78, 216, 0.10);
    --btn-bg: #1d4ed8;
    --btn-fg: #ffffff;
    --btn-bg-hover: #1e40af;
    --result: #047857;
    --negative: #b91c1c;
}

:root {
    --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --radius: 14px;
    --radius-pill: 100px;
    --transition: 0.2s ease;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    background-color: var(--bg);
    color: var(--text);
    font-family: var(--font-sans);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
    border-radius: 4px;
}

.sr-only {
    position: absolute;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
    border: 0;
}

/* ── Header ── */
header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.1rem 1.5rem;
    max-width: 860px;
    width: 100%;
    margin: 0 auto;
}

.logo {
    font-size: 1.15rem;
    font-weight: 800;
    letter-spacing: -0.04em;
    color: var(--text);
    text-decoration: none;
    display: flex;
    align-items: baseline;
    gap: 0.28em;
}
.logo .op { color: var(--accent); font-weight: 600; font-size: 0.95em; }
.logo .eq { color: var(--text-muted); font-weight: 600; font-size: 0.95em; }
.logo .caret {
    align-self: center;
    width: 0.42em;
    height: 0.9em;
    border-radius: 2px;
    background: var(--result);
}

.header-actions { display: flex; align-items: center; gap: 0.5rem; margin-left: auto; }

.icon-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border: none;
    border-radius: var(--radius-pill);
    background: var(--surface);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}
.icon-btn:hover { background: var(--accent-subtle); color: var(--accent); }
.icon-btn svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
:root[data-theme="dark"] .i-moon { display: none; }
:root[data-theme="light"] .i-sun { display: none; }

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.45rem 0.9rem;
    border-radius: var(--radius-pill);
    background: var(--surface);
    color: var(--text-secondary);
    font-size: 0.78rem;
    font-weight: 600;
    text-decoration: none;
    transition: all var(--transition);
}
.back-link:hover { background: var(--accent-subtle); color: var(--accent); }

/* ── Page body ── */
main {
    flex: 1;
    max-width: 860px;
    width: 100%;
    margin: 0 auto;
    padding: 0.5rem 1.5rem 3rem;
}

.page-head { margin-bottom: 1.75rem; }
.page-head h1 {
    font-size: 1.9rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.15;
    margin-bottom: 0.6rem;
}
.page-head .lede { font-size: 1rem; color: var(--text-secondary); max-width: 60ch; }
.page-head .updated {
    display: inline-block;
    margin-top: 0.9rem;
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.prose {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.75rem 2rem 2rem;
}
.prose h2 {
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin: 1.9rem 0 0.6rem;
    padding-top: 1.4rem;
    border-top: 1px solid var(--hairline);
}
.prose h2:first-child { margin-top: 0; padding-top: 0; border-top: none; }
.prose h3 { font-size: 0.9rem; font-weight: 700; color: var(--text); margin: 1.2rem 0 0.4rem; }
.prose p, .prose li { font-size: 0.9rem; color: var(--text-secondary); }
.prose p + p { margin-top: 0.75rem; }
.prose ul { margin: 0.6rem 0 0 1.1rem; display: flex; flex-direction: column; gap: 0.45rem; }
.prose a { color: var(--accent); }
.prose strong { color: var(--text); }

.keynote {
    background: var(--accent-subtle);
    border-radius: var(--radius);
    padding: 1rem 1.15rem;
    margin: 1.1rem 0;
}
.keynote p { color: var(--text); font-weight: 500; }

.todo {
    background: var(--surface-raised);
    border-radius: 4px;
    padding: 0.05rem 0.35rem;
    font-weight: 600;
    color: var(--text);
}

/* ══ Landing pages ══════════════════════════════════════════
   Everything below is used by the keyword landing pages. They share
   this stylesheet with privacy/terms so there is one place to edit. */

:root { --font-mono: 'SF Mono', SFMono-Regular, Consolas, 'Liberation Mono', Menlo, Courier, monospace; }

/* The link into the tool. Repeated near the top and again after the
   worked examples — that second one is the click that converts. */
.cta {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.7rem 1.35rem;
    margin-bottom: 1.75rem;
    border-radius: var(--radius-pill);
    background: var(--btn-bg);
    color: var(--btn-fg);
    font-size: 0.88rem;
    font-weight: 700;
    text-decoration: none;
    transition: all var(--transition);
}
.cta:hover { background: var(--btn-bg-hover); }
.prose .cta { color: var(--btn-fg); margin: 1.75rem 0 0.5rem; }

.prose code {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    background: var(--accent-subtle);
    color: var(--accent);
    padding: 0.12rem 0.4rem;
    border-radius: 5px;
    white-space: nowrap;
}

/* A worked example, rendered as real markup rather than a screenshot —
   it is the part of the page a search engine can actually read. */
.worked-example {
    background: var(--surface-raised);
    border-radius: var(--radius);
    padding: 1.15rem 1.3rem;
    margin: 1.25rem 0;
    overflow-x: auto;
}
.worked-example table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.worked-example caption {
    text-align: left;
    font-size: 0.65rem;
    font-weight: 700;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.09em;
    padding-bottom: 0.7rem;
}
.worked-example td { padding: 0.4rem 0; color: var(--result); font-weight: 600; }
.worked-example td:first-child { width: 100%; color: var(--text-secondary); font-weight: 400; }
.worked-example .op {
    padding: 0 0.7rem;
    text-align: center;
    font-family: var(--font-mono);
    opacity: 0.85;
}
.worked-example .num {
    text-align: right;
    white-space: nowrap;
    font-family: var(--font-mono);
    font-variant-numeric: tabular-nums;
}
.worked-example tr.neg td:not(:first-child) { color: var(--negative); }
.worked-example tr.derived td:not(:first-child) { color: var(--text); }
.worked-example tr.derived .op { color: var(--accent); opacity: 1; }
.worked-example tfoot td {
    padding-top: 0.7rem;
    border-top: 1px solid var(--hairline);
    color: var(--text);
    font-weight: 800;
}
.worked-example .note {
    margin-top: 0.9rem;
    font-size: 0.78rem;
    color: var(--text-muted);
    line-height: 1.55;
}

/* ── FAQ. <details> keeps the answers in the markup for crawlers
      while the page stays scannable. ── */
.faq { margin-top: 0.5rem; }
.faq details { border-top: 1px solid var(--hairline); }
.faq details:last-child { border-bottom: 1px solid var(--hairline); }
.faq summary {
    cursor: pointer;
    padding: 0.85rem 0;
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--text);
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    transition: color var(--transition);
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary:hover { color: var(--accent); }
.faq summary::after {
    content: '+';
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--text-muted);
    flex-shrink: 0;
}
.faq details[open] summary::after { content: '−'; }
.faq details p { padding: 0 0 1rem; }

.related { margin-top: 0.6rem; }

/* On a narrow screen a three-column worked example pushes the numbers off
   the right edge, so the reader sees the input lines and none of the
   results. Stack each row instead: the typed line, then its value beneath. */
@media (max-width: 620px) {
    .worked-example { overflow-x: visible; padding: 1rem 1.1rem; }
    .worked-example table,
    .worked-example tbody,
    .worked-example tfoot { display: block; width: 100%; }
    .worked-example caption { display: block; }

    .worked-example tr {
        display: grid;
        grid-template-columns: 1fr auto auto;
        column-gap: 0.55rem;
        padding: 0.6rem 0;
        border-bottom: 1px solid var(--hairline);
    }
    .worked-example tr:last-child { border-bottom: none; }
    .worked-example td { display: block; padding: 0; }
    .worked-example td:first-child { grid-column: 1 / -1; margin-bottom: 0.4rem; }
    .worked-example .op { grid-column: 2; text-align: right; padding: 0; }
    .worked-example .num { grid-column: 3; text-align: right; }
    .worked-example code { white-space: normal; overflow-wrap: anywhere; }

    /* The total keeps its label and figure on one line. */
    .worked-example tfoot tr {
        grid-template-columns: 1fr auto;
        border-top: 1px solid var(--hairline);
        border-bottom: none;
        margin-top: 0.2rem;
    }
    .worked-example tfoot td:first-child { grid-column: 1; margin-bottom: 0; }
    .worked-example tfoot td:nth-child(2) { display: none; }
    .worked-example tfoot .num { grid-column: 2; }
}

/* ── Footer ── */
footer {
    padding: 2rem 1.5rem;
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: auto;
    line-height: 1.8;
}
footer a { color: var(--text-secondary); text-decoration: none; }
footer a:hover { color: var(--accent); text-decoration: underline; }
.footer-line { display: flex; justify-content: center; flex-wrap: wrap; gap: 0.5rem; }
.footer-line .sep { color: var(--text-muted); opacity: 0.55; }

@media (max-width: 600px) {
    header { padding: 0.9rem 1rem; }
    main { padding: 0.5rem 1rem 2rem; }
    .page-head h1 { font-size: 1.5rem; }
    .prose { padding: 1.25rem 1.15rem 1.5rem; }
}