:root {
    --ch-bg: #f6f8fb;
    --ch-surface: #ffffff;
    --ch-text: #122033;
    --ch-muted: #65738a;
    --ch-border: #e4e9f2;
    --ch-primary: #2357c6;
    --ch-primary-dark: #163e99;
    --ch-health: #18a058;
    --ch-finance: #2563eb;
    --ch-education: #7c3aed;
    --ch-math: #f97316;
    --ch-business: #0f766e;
    --ch-daily: #4f46e5;
    --ch-radius: 20px;
    --ch-shadow: 0 18px 45px rgba(18, 32, 51, 0.08);
    --ch-container: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
    background: var(--ch-bg);
    color: var(--ch-text);
    line-height: 1.65;
}

a { color: var(--ch-primary); text-decoration: none; }
a:hover { color: var(--ch-primary-dark); }
img { max-width: 100%; height: auto; }

.calchub-container {
    width: min(100% - 32px, var(--ch-container));
    margin-inline: auto;
}

.screen-reader-text {
    border: 0;
    clip: rect(1px, 1px, 1px, 1px);
    clip-path: inset(50%);
    height: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    width: 1px;
    word-wrap: normal !important;
}

.skip-link:focus {
    clip: auto;
    clip-path: none;
    width: auto;
    height: auto;
    z-index: 99999;
    top: 12px;
    left: 12px;
    background: #fff;
    padding: 10px 14px;
    border-radius: 10px;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.94);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--ch-border);
}

.site-header-inner {
    min-height: 76px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.site-branding { display: flex; flex-direction: column; justify-content: center; min-width: 170px; }
.site-title {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--ch-text);
    letter-spacing: -0.02em;
}
.site-description { margin: 0; color: var(--ch-muted); font-size: 0.85rem; }
.custom-logo { max-height: 58px; width: auto; display: block; }

.primary-navigation { display: flex; align-items: center; }
.primary-menu {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
    margin: 0;
    padding: 0;
}
.primary-menu li { position: relative; }
.primary-menu a {
    display: block;
    padding: 10px 14px;
    border-radius: 999px;
    color: var(--ch-text);
    font-weight: 650;
    font-size: 0.95rem;
}
.primary-menu a:hover,
.primary-menu .current-menu-item > a {
    background: #eef4ff;
    color: var(--ch-primary);
}

.menu-toggle {
    display: none;
    width: 46px;
    height: 42px;
    border: 1px solid var(--ch-border);
    border-radius: 14px;
    background: #fff;
    cursor: pointer;
    padding: 9px;
}
.menu-toggle-line {
    display: block;
    height: 2px;
    background: var(--ch-text);
    margin: 5px 0;
    border-radius: 99px;
}

.site-main { min-height: 60vh; }

.hero-section {
    padding: 72px 0 42px;
    background:
        radial-gradient(circle at top left, rgba(35, 87, 198, 0.14), transparent 36%),
        linear-gradient(135deg, #ffffff 0%, #edf4ff 100%);
}
.hero-grid {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    align-items: center;
    gap: 42px;
}
.hero-badge {
    display: inline-flex;
    padding: 8px 14px;
    border-radius: 999px;
    background: #e9f0ff;
    color: var(--ch-primary);
    font-weight: 750;
    margin-bottom: 16px;
}
.hero-copy h1 {
    font-size: clamp(2.2rem, 5vw, 4.6rem);
    line-height: 1.05;
    margin: 0 0 18px;
    letter-spacing: -0.055em;
}
.hero-copy p {
    color: var(--ch-muted);
    font-size: 1.12rem;
    max-width: 650px;
    margin: 0 0 28px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; }
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 46px;
    padding: 11px 20px;
    border-radius: 999px;
    font-weight: 750;
    border: 1px solid transparent;
}
.btn-primary { background: var(--ch-primary); color: #fff; }
.btn-primary:hover { background: var(--ch-primary-dark); color: #fff; }
.btn-light { background: #fff; color: var(--ch-text); border-color: var(--ch-border); }

.hero-panel {
    display: grid;
    gap: 18px;
    padding: 28px;
    border-radius: 32px;
    background: rgba(255,255,255,0.72);
    border: 1px solid rgba(255,255,255,0.8);
    box-shadow: var(--ch-shadow);
}
.mini-calculator-card {
    background: #fff;
    border-left: 6px solid var(--ch-health);
    border-radius: 20px;
    padding: 18px 20px;
    box-shadow: 0 10px 28px rgba(18,32,51,.07);
}
.mini-calculator-card.finance { border-left-color: var(--ch-finance); }
.mini-calculator-card.education { border-left-color: var(--ch-education); }
.mini-calculator-card span { display: block; color: var(--ch-muted); font-weight: 750; }
.mini-calculator-card strong { display: block; font-size: 2rem; line-height: 1.1; }
.mini-calculator-card small { color: var(--ch-muted); }

.category-section,
.content-section,
.page-content-section,
.single-section { padding: 44px 0; }
.section-heading { text-align: center; max-width: 760px; margin: 0 auto 28px; }
.section-heading h2 { font-size: clamp(1.7rem, 3vw, 2.4rem); margin: 0 0 8px; letter-spacing: -0.03em; }
.section-heading p { color: var(--ch-muted); margin: 0; }
.category-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 18px;
}
.category-card,
.content-card,
.page-content-card,
.single-card,
.post-card {
    background: var(--ch-surface);
    border: 1px solid var(--ch-border);
    border-radius: var(--ch-radius);
    box-shadow: var(--ch-shadow);
}
.category-card { padding: 24px; border-top: 6px solid var(--ch-primary); }
.category-card h3 { margin: 0 0 8px; font-size: 1.25rem; }
.category-card p { margin: 0; color: var(--ch-muted); }
.category-card.health { border-top-color: var(--ch-health); }
.category-card.finance { border-top-color: var(--ch-finance); }
.category-card.education { border-top-color: var(--ch-education); }
.category-card.math { border-top-color: var(--ch-math); }
.category-card.business { border-top-color: var(--ch-business); }
.category-card.daily { border-top-color: var(--ch-daily); }

.content-card,
.page-content-card,
.single-card { padding: clamp(22px, 4vw, 44px); }
.entry-content > *:first-child { margin-top: 0; }
.entry-content > *:last-child { margin-bottom: 0; }
.entry-content h1,
.entry-content h2,
.entry-content h3 { line-height: 1.2; letter-spacing: -0.02em; }
.entry-content table { width: 100%; border-collapse: collapse; overflow-x: auto; display: block; }
.entry-content th,
.entry-content td { border: 1px solid var(--ch-border); padding: 10px; }
.entry-content input,
.entry-content select,
.entry-content textarea,
.entry-content button {
    max-width: 100%;
    font: inherit;
}

.post-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.post-card { overflow: hidden; }
.post-card-title { margin: 16px 18px 8px; font-size: 1.15rem; line-height: 1.25; }
.post-card-title a { color: var(--ch-text); }
.post-card-excerpt { margin: 0 18px 20px; color: var(--ch-muted); }
.post-thumb img { display: block; width: 100%; aspect-ratio: 16/10; object-fit: cover; }
.single-title { margin: 0 0 20px; font-size: clamp(2rem, 4vw, 3rem); line-height: 1.1; }
.single-featured-image img { width: 100%; border-radius: 18px; margin-bottom: 24px; }

.site-footer {
    background: #0f172a;
    color: #dbe6ff;
    margin-top: 36px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 1.4fr 1fr 1fr 1fr;
    gap: 28px;
    padding: 48px 0;
}
.site-footer h2,
.site-footer h3 { color: #fff; margin-top: 0; }
.site-footer p,
.site-footer a { color: #c8d3ea; }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li + li { margin-top: 8px; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.1); padding: 16px 0; }
.footer-bottom p { margin: 0; font-size: .92rem; }

@media (max-width: 900px) {
    .site-header-inner { min-height: 68px; }
    .menu-toggle { display: block; }
    .primary-navigation {
        position: absolute;
        inset: 68px 16px auto 16px;
        display: none;
        background: #fff;
        border: 1px solid var(--ch-border);
        border-radius: 20px;
        box-shadow: var(--ch-shadow);
        padding: 12px;
    }
    .primary-navigation.is-open { display: block; }
    .primary-menu { display: block; }
    .primary-menu a { border-radius: 12px; padding: 12px 14px; }
    .hero-grid { grid-template-columns: 1fr; gap: 26px; }
    .hero-section { padding: 44px 0 32px; }
    .category-grid { grid-template-columns: repeat(2, 1fr); }
    .post-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 620px) {
    .calchub-container { width: min(100% - 22px, var(--ch-container)); }
    .hero-actions .btn { width: 100%; }
    .hero-panel { padding: 16px; border-radius: 24px; }
    .category-grid,
    .post-grid,
    .footer-grid { grid-template-columns: 1fr; }
    .category-section,
    .content-section,
    .page-content-section,
    .single-section { padding: 28px 0; }
    .content-card,
    .page-content-card,
    .single-card { padding: 18px; border-radius: 16px; }
    .site-branding { min-width: 0; }
    .site-title { font-size: 1.1rem; }
    .site-description { display: none; }
}

/* v1.1 Calculator Engine */
.archive-hero,
.single-calculator-hero {
    padding: 64px 0 34px;
    background: linear-gradient(135deg, rgba(37,99,235,.10), rgba(22,163,74,.10));
}
.archive-hero h1,
.single-calculator-hero h1 {
    margin: 12px 0 10px;
    font-size: clamp(2rem, 4vw, 3.5rem);
    line-height: 1.08;
}
.archive-hero p,
.single-calculator-hero p {
    max-width: 760px;
    color: var(--calchub-muted, #667085);
    font-size: 1.05rem;
}
.calculator-category-strip {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    padding-top: 28px;
    padding-bottom: 10px;
}
.calculator-chip {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 14px;
    border-radius: 999px;
    border: 1px solid rgba(15,23,42,.10);
    color: #111827;
    background: #fff;
    text-decoration: none;
    box-shadow: 0 8px 20px rgba(15,23,42,.06);
}
.calculator-chip span {
    color: var(--chip-color);
    font-weight: 800;
}
.calculator-list-section {
    padding-top: 22px;
    padding-bottom: 60px;
}
.calculator-card-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 22px;
}
.calculator-list-card,
.calculator-main-card,
.calculator-info-card,
.calculator-empty-state {
    background: #fff;
    border: 1px solid rgba(15,23,42,.08);
    border-radius: 22px;
    box-shadow: 0 12px 34px rgba(15,23,42,.08);
}
.calculator-list-card {
    padding: 24px;
}
.calculator-list-card h2 {
    font-size: 1.25rem;
    margin: 10px 0 8px;
}
.calculator-list-card h2 a,
.calculator-card-link {
    color: inherit;
    text-decoration: none;
}
.calculator-card-label {
    display: inline-flex;
    border-radius: 999px;
    background: rgba(37,99,235,.10);
    color: #1d4ed8;
    padding: 6px 10px;
    font-size: .82rem;
    font-weight: 700;
}
.calculator-list-card p {
    color: var(--calchub-muted, #667085);
}
.calculator-card-link {
    display: inline-flex;
    margin-top: 10px;
    font-weight: 800;
    color: #2563eb;
}
.single-calculator-layout {
    display: grid;
    grid-template-columns: minmax(0, 1.1fr) minmax(280px, .65fr);
    gap: 26px;
    padding-top: 36px;
    padding-bottom: 70px;
    align-items: start;
}
.calculator-main-card,
.calculator-info-card,
.calculator-empty-state {
    padding: 28px;
}
.calculator-tool label {
    display: flex;
    flex-direction: column;
    gap: 8px;
    font-weight: 700;
    color: #111827;
}
.calculator-form-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
    margin-bottom: 20px;
}
.calculator-form-grid input,
.calculator-form-grid select {
    width: 100%;
    border: 1px solid rgba(15,23,42,.14);
    border-radius: 14px;
    padding: 13px 14px;
    font-size: 1rem;
    background: #fff;
}
.calculator-result {
    margin-top: 18px;
    padding: 18px;
    border-radius: 16px;
    background: rgba(22,163,74,.09);
    color: #14532d;
    font-weight: 800;
    border: 1px solid rgba(22,163,74,.18);
}
.calculator-info-card h2 {
    margin-top: 0;
    font-size: 1.25rem;
}
.calculator-empty-state {
    color: var(--calchub-muted, #667085);
    text-align: center;
}

@media (max-width: 900px) {
    .calculator-card-grid,
    .single-calculator-layout {
        grid-template-columns: 1fr;
    }
}
@media (max-width: 560px) {
    .archive-hero,
    .single-calculator-hero {
        padding: 42px 0 26px;
    }
    .calculator-form-grid {
        grid-template-columns: 1fr;
    }
    .calculator-main-card,
    .calculator-info-card {
        padding: 20px;
        border-radius: 18px;
    }
    .calculator-category-strip {
        gap: 8px;
    }
    .calculator-chip {
        flex: 1 1 auto;
        justify-content: center;
    }
}

/* v1.2 Custom Article System */
.article-hero,
.single-article-hero {
    padding: 64px 0 34px;
    background: linear-gradient(135deg, rgba(124,58,237,.11), rgba(37,99,235,.09));
}
.article-hero h1,
.single-article-hero h1 {
    margin: 12px 0 10px;
    font-size: clamp(2rem, 4vw, 3.5rem);
    line-height: 1.08;
    letter-spacing: -0.04em;
}
.article-hero p,
.single-article-hero p {
    max-width: 780px;
    color: var(--ch-muted);
    font-size: 1.05rem;
}
.article-category-strip {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    padding-top: 28px;
    padding-bottom: 10px;
}
.article-chip {
    display: inline-flex;
    padding: 10px 14px;
    border-radius: 999px;
    border: 1px solid rgba(15,23,42,.10);
    color: #111827;
    background: #fff;
    box-shadow: 0 8px 20px rgba(15,23,42,.06);
    font-weight: 750;
}
.article-list-section {
    padding-top: 22px;
    padding-bottom: 60px;
}
.article-card-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 22px;
}
.article-list-card,
.single-article-card,
.article-sidebar-card,
.article-empty-state {
    background: #fff;
    border: 1px solid rgba(15,23,42,.08);
    border-radius: 22px;
    box-shadow: 0 12px 34px rgba(15,23,42,.08);
}
.article-list-card {
    overflow: hidden;
}
.article-thumb img {
    width: 100%;
    display: block;
    aspect-ratio: 16/10;
    object-fit: cover;
}
.article-card-body {
    padding: 22px;
}
.article-meta-row {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    color: var(--ch-muted);
    font-size: .88rem;
    font-weight: 750;
}
.article-meta-row span {
    display: inline-flex;
    padding: 6px 10px;
    background: rgba(124,58,237,.09);
    color: #5b21b6;
    border-radius: 999px;
}
.article-list-card h2 {
    font-size: 1.25rem;
    line-height: 1.25;
    margin: 14px 0 8px;
}
.article-list-card h2 a {
    color: var(--ch-text);
}
.article-list-card p,
.article-sidebar-card p {
    color: var(--ch-muted);
}
.article-card-link {
    display: inline-flex;
    margin-top: 10px;
    font-weight: 800;
    color: #6d28d9;
}
.single-article-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 26px;
    align-items: start;
    padding-top: 36px;
    padding-bottom: 70px;
}
.single-article-card,
.article-sidebar-card,
.article-empty-state {
    padding: 28px;
}
.hero-meta {
    margin-bottom: 12px;
}
.related-calculator-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.related-calculator-list li + li {
    margin-top: 10px;
}
.related-calculator-list a {
    display: block;
    padding: 12px 14px;
    border-radius: 14px;
    background: rgba(37,99,235,.08);
    color: #1d4ed8;
    font-weight: 800;
}
.article-empty-state {
    color: var(--ch-muted);
    text-align: center;
}
@media (max-width: 900px) {
    .article-card-grid,
    .single-article-layout {
        grid-template-columns: 1fr;
    }
}
@media (max-width: 560px) {
    .article-hero,
    .single-article-hero {
        padding: 42px 0 26px;
    }
    .article-card-body,
    .single-article-card,
    .article-sidebar-card {
        padding: 20px;
        border-radius: 18px;
    }
    .article-category-strip {
        gap: 8px;
    }
    .article-chip {
        flex: 1 1 auto;
        justify-content: center;
    }
}

/* v1.3 User Account Manager */
.site-account-area { display: flex; align-items: center; }
.header-account-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 40px;
    padding: 8px 14px;
    border: 1px solid var(--ch-border);
    border-radius: 999px;
    background: #fff;
    color: var(--ch-text);
    font-weight: 800;
    font-size: .92rem;
    white-space: nowrap;
}
.header-account-link:hover { color: var(--ch-primary); border-color: var(--ch-primary); }
.calchub-account-wrap,
.calchub-dashboard { width: min(100% - 32px, 1040px); margin: 36px auto; }
.calchub-account-card,
.dashboard-hero,
.dashboard-panel,
.dashboard-card {
    background: #fff;
    border: 1px solid var(--ch-border);
    border-radius: 24px;
    box-shadow: var(--ch-shadow);
}
.calchub-account-card { max-width: 520px; margin: 0 auto; padding: clamp(24px, 5vw, 42px); }
.calchub-account-card h1,
.dashboard-hero h1 { margin: 0 0 8px; }
.account-muted { color: var(--ch-muted); }
.calchub-account-form { display: grid; gap: 16px; margin-top: 22px; }
.calchub-account-form label { display: grid; gap: 7px; font-weight: 800; color: var(--ch-text); }
.calchub-account-form input[type="text"],
.calchub-account-form input[type="email"],
.calchub-account-form input[type="password"] {
    width: 100%;
    min-height: 48px;
    border: 1px solid var(--ch-border);
    border-radius: 14px;
    padding: 10px 14px;
    font: inherit;
}
.inline-check { display: flex !important; grid-template-columns: none !important; align-items: center; gap: 10px !important; font-weight: 700 !important; }
.calchub-alert { padding: 12px 14px; border-radius: 14px; background: #fff4f4; color: #9f1239; border: 1px solid #fecdd3; margin-top: 14px; }
.account-switch { margin: 18px 0 0; color: var(--ch-muted); }
.dashboard-hero { padding: clamp(24px, 4vw, 44px); display: flex; align-items: center; justify-content: space-between; gap: 18px; background: linear-gradient(135deg, #eef8ff, #f8fafc); }
.dashboard-eyebrow { display: inline-block; color: var(--ch-primary); font-weight: 900; text-transform: uppercase; letter-spacing: .08em; font-size: .78rem; margin-bottom: 8px; }
.dashboard-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin: 22px 0; }
.dashboard-card { padding: 22px; }
.dashboard-card strong { display: block; font-size: 1.4rem; color: var(--ch-text); overflow-wrap: anywhere; }
.dashboard-card span { display: block; color: var(--ch-muted); font-weight: 750; margin-top: 6px; }
.dashboard-panel { padding: clamp(22px, 4vw, 34px); }
.dashboard-panel h2 { margin-top: 0; }
.calculator-hero-action { margin-top: 16px; }
.calchub-save-calculator.is-saved { border-color: var(--ch-primary); color: var(--ch-primary); }
.calchub-save-calculator.is-working { opacity: .75; pointer-events: none; }
@media (max-width: 900px) {
    .site-header-inner { flex-wrap: wrap; }
    .site-account-area { order: 3; width: 100%; justify-content: flex-end; }
    .dashboard-grid { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
    .calchub-account-wrap,
    .calchub-dashboard { width: min(100% - 22px, 1040px); margin: 22px auto; }
    .dashboard-hero { align-items: flex-start; flex-direction: column; }
    .header-account-link { width: 100%; }
}

/* v1.5 Universal Design Polish */
:root {
    --ch-focus: 0 0 0 4px rgba(35,87,198,.16);
}
.site-main { min-height: 58vh; }
.primary-menu a,
.header-account-link,
.calculator-card-link,
.calculator-chip,
.article-chip,
button,
input,
select,
textarea { transition: color .18s ease, background .18s ease, border-color .18s ease, transform .18s ease, box-shadow .18s ease; }
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
    outline: none;
    box-shadow: var(--ch-focus);
}
.calculator-list-card {
    position: relative;
    overflow: hidden;
    border-top: 5px solid var(--cat-color, var(--ch-primary));
}
.calculator-list-card::before {
    content: "";
    position: absolute;
    inset: 0 0 auto 0;
    height: 92px;
    background: linear-gradient(135deg, var(--cat-soft, #edf3ff), transparent 70%);
    pointer-events: none;
}
.calculator-list-card > * { position: relative; }
.calculator-list-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 18px 42px rgba(15,23,42,.11);
}
.calculator-card-label {
    background: var(--cat-soft, rgba(37,99,235,.10));
    color: var(--cat-text, #1d4ed8);
}
.calculator-card-link { color: var(--cat-text, #2563eb); }
.single-calculator-hero {
    background: linear-gradient(135deg, var(--cat-soft, #eef4ff), #ffffff 68%);
}
.single-calculator-hero .hero-badge,
.calculator-main-card .calculator-result,
.calculator-tool button {
    background: var(--cat-color, var(--ch-primary));
}
.calculator-main-card {
    border-top: 5px solid var(--cat-color, var(--ch-primary));
}
.calculator-tool input,
.calculator-tool select,
.calculator-tool textarea,
.calchub-account-form input[type="text"],
.calchub-account-form input[type="email"],
.calchub-account-form input[type="password"] {
    background: #fff;
    border-color: #dbe3ee;
}
.calculator-tool input:focus,
.calculator-tool select:focus,
.calculator-tool textarea:focus {
    border-color: var(--cat-color, var(--ch-primary));
}
.calculator-category-strip,
.article-category-strip { scrollbar-width: thin; }
.calculator-chip:hover,
.article-chip:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 24px rgba(15,23,42,.08);
}
img[loading="lazy"] { content-visibility: auto; }
.entry-content img,
.article-card img,
.calculator-list-card img { border-radius: 16px; }

@media (max-width: 1024px) {
    .calchub-container { width: min(100% - 28px, var(--ch-container)); }
    .calculator-card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .site-header-inner { min-height: 68px; }
}
@media (max-width: 768px) {
    body { line-height: 1.58; }
    .site-header { position: sticky; }
    .calculator-card-grid,
    .article-card-grid,
    .dashboard-grid { gap: 14px; }
    .calculator-list-card,
    .article-card-body,
    .calculator-main-card,
    .calculator-info-card,
    .dashboard-card { padding: 20px; }
    .single-calculator-layout { gap: 16px; padding-top: 22px; padding-bottom: 42px; }
    .calculator-category-strip,
    .article-category-strip {
        display: flex;
        overflow-x: auto;
        padding-bottom: 8px;
        -webkit-overflow-scrolling: touch;
    }
    .calculator-chip,
    .article-chip { white-space: nowrap; }
}
@media (max-width: 560px) {
    .calchub-container { width: min(100% - 20px, var(--ch-container)); }
    .calculator-card-grid { grid-template-columns: 1fr; }
    .archive-hero h1,
    .single-calculator-hero h1,
    .article-hero h1,
    .single-article-hero h1 { font-size: clamp(1.8rem, 10vw, 2.4rem); }
    .menu-toggle { min-width: 44px; min-height: 44px; }
    .primary-menu a { min-height: 44px; display: flex; align-items: center; }
    .calculator-tool label { font-size: .95rem; }
    .calculator-tool input,
    .calculator-tool select,
    .calculator-tool button { min-height: 48px; font-size: 16px; }
    .site-account-area { justify-content: stretch; }
}
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        scroll-behavior: auto !important;
        transition-duration: .01ms !important;
        animation-duration: .01ms !important;
        animation-iteration-count: 1 !important;
    }
}

/* v1.5.1 Homepage UI Refinement - Upgrade Only */
body {
    background: #f7fbff;
}
.site-header {
    background: rgba(255,255,255,.98);
    box-shadow: 0 10px 30px rgba(15,23,42,.04);
}
.site-title {
    font-size: 1.85rem;
    color: #071936;
}
.site-title::first-letter { color: #0b63f6; }
.site-description {
    color: #42526f;
    margin-top: -3px;
}
.primary-menu a {
    border-radius: 0;
    padding: 22px 16px 18px;
    color: #071936;
    position: relative;
}
.primary-menu a:hover,
.primary-menu .current-menu-item > a {
    background: transparent;
    color: #075ff2;
}
.primary-menu a:after,
.primary-menu .current-menu-item > a:after {
    content: "";
    position: absolute;
    left: 16px;
    right: 16px;
    bottom: 8px;
    height: 3px;
    border-radius: 99px;
    background: #075ff2;
    transform: scaleX(0);
    transition: transform .22s ease;
}
.primary-menu a:hover:after,
.primary-menu .current-menu-item > a:after { transform: scaleX(1); }
.site-account-area a,
.calchub-account-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 13px 18px;
    border-radius: 999px;
    background: #0b63f6;
    color: #fff !important;
    font-weight: 800;
    box-shadow: 0 10px 24px rgba(11,99,246,.18);
}
.calchub-home-hero { padding: 28px 0 18px; }
.home-hero-card {
    min-height: 320px;
    display: grid;
    grid-template-columns: 1.05fr .95fr;
    align-items: center;
    gap: 30px;
    overflow: hidden;
    position: relative;
    border-radius: 20px;
    padding: clamp(26px, 5vw, 58px) clamp(22px, 6vw, 78px);
    background:
        radial-gradient(circle at 8% 38%, rgba(181,216,255,.9), transparent 4%),
        radial-gradient(circle at 93% 23%, rgba(207,245,239,.95), transparent 7%),
        radial-gradient(circle at 78% 82%, rgba(154,217,247,.35), transparent 22%),
        linear-gradient(105deg, #eaf5ff 0%, #f4fbff 52%, #eefbe8 100%);
    box-shadow: 0 18px 40px rgba(38,76,118,.06);
}
.home-hero-card:before {
    content: "";
    position: absolute;
    inset: 0;
    background-image: radial-gradient(rgba(14,99,246,.13) 2px, transparent 2px);
    background-size: 22px 22px;
    background-position: 56% 18%;
    mask-image: radial-gradient(circle at 56% 18%, #000 0 12%, transparent 20%);
    pointer-events: none;
}
.home-hero-copy { position: relative; z-index: 2; }
.home-hero-copy .hero-badge {
    background: #fff;
    color: #0b63f6;
    box-shadow: 0 8px 20px rgba(12,99,246,.08);
}
.home-hero-copy h1 {
    margin: 14px 0 14px;
    font-size: clamp(2.8rem, 6vw, 5rem);
    line-height: .96;
    letter-spacing: -.06em;
    color: #071936;
}
.home-hero-copy h1::first-line { color: #0b63f6; }
.home-hero-copy p {
    max-width: 590px;
    font-size: 1.08rem;
    color: #243553;
    margin: 0 0 24px;
}
.home-search {
    display: grid;
    grid-template-columns: 44px 1fr auto;
    align-items: center;
    width: min(100%, 560px);
    min-height: 58px;
    background: #fff;
    border: 1px solid #dfe8f5;
    border-radius: 18px;
    overflow: hidden;
    box-shadow: 0 12px 25px rgba(15,23,42,.05);
}
.home-search span { text-align: center; color: #49627f; font-size: 1.3rem; }
.home-search input {
    border: 0;
    outline: 0;
    font: inherit;
    color: #071936;
    min-width: 0;
}
.home-search button {
    align-self: stretch;
    border: 0;
    padding: 0 26px;
    background: #0b63f6;
    color: #fff;
    font-weight: 800;
    cursor: pointer;
}
.home-hero-art {
    min-height: 260px;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}
.big-calculator {
    width: 220px;
    padding: 18px;
    border-radius: 24px;
    background: linear-gradient(155deg, #6478ff 0%, #1a51c9 100%);
    box-shadow: 0 22px 36px rgba(10,65,190,.25), inset 0 0 0 3px rgba(255,255,255,.12);
    transform: rotate(.5deg);
}
.calc-display {
    background: #eaf5ff;
    color: #284fc2;
    border-radius: 10px;
    padding: 12px 13px;
    text-align: right;
    font-size: 1.65rem;
    font-weight: 800;
    margin-bottom: 14px;
    letter-spacing: .04em;
}
.calc-keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 9px;
}
.calc-keys span {
    display: grid;
    place-items: center;
    min-height: 38px;
    border-radius: 9px;
    background: rgba(255,255,255,.55);
    color: #fff;
    font-weight: 850;
    box-shadow: inset 0 -3px 0 rgba(0,0,0,.07);
}
.floating-ops {
    display: grid;
    gap: 16px;
    margin-right: 34px;
    z-index: 2;
}
.op {
    width: 48px;
    height: 48px;
    display: grid;
    place-items: center;
    border-radius: 12px;
    color: #fff;
    font-size: 2rem;
    font-weight: 900;
    box-shadow: 0 12px 25px rgba(15,23,42,.16);
}
.op.plus { background: linear-gradient(135deg, #5bdb6b, #16a34a); }
.op.minus { background: linear-gradient(135deg, #ffb144, #f97316); }
.op.times { background: linear-gradient(135deg, #a855f7, #6d28d9); }
.op.equals { background: linear-gradient(135deg, #3182ff, #075ff2); }
.home-category-section,
.home-popular-section { padding: 22px 0 8px; }
.home-section-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 16px;
}
.home-section-row h2 {
    margin: 0;
    font-size: 1.45rem;
    letter-spacing: -.03em;
}
.home-section-row a { font-weight: 800; }
.home-category-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 22px;
}
.home-category-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    min-height: 142px;
    padding: 22px 14px;
    border-radius: 12px;
    background: #fff;
    border: 1px solid #dfe8f5;
    box-shadow: 0 16px 32px rgba(15,23,42,.05);
    color: #081936;
    border-bottom: 4px solid var(--cat-color, #0b63f6);
    transition: transform .2s ease, box-shadow .2s ease;
}
.home-category-card:hover { transform: translateY(-3px); box-shadow: 0 18px 40px rgba(15,23,42,.09); }
.category-icon {
    width: 58px;
    height: 58px;
    border-radius: 50%;
    display: grid;
    place-items: center;
    margin-bottom: 14px;
    background: linear-gradient(135deg, var(--cat-light), var(--cat-color));
    color: #fff;
    font-size: 1.8rem;
    font-weight: 900;
}
.home-category-card strong { font-size: 1.1rem; }
.home-category-card small { color: #42526f; margin-top: 2px; }
.health { --cat-color: #28bd51; --cat-light: #62e078; }
.finance { --cat-color: #0b8df6; --cat-light: #4fb0ff; }
.education { --cat-color: #8247e5; --cat-light: #a66cff; }
.math { --cat-color: #ff850b; --cat-light: #ffae46; }
.business { --cat-color: #04a7a7; --cat-light: #27d0c9; }
.daily { --cat-color: #4158d9; --cat-light: #6b7ef2; }
.popular-calculator-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 18px;
}
.popular-calculator-card {
    display: grid;
    grid-template-columns: 58px 1fr auto;
    align-items: center;
    gap: 14px;
    min-height: 92px;
    padding: 14px;
    border-radius: 12px;
    color: #081936;
    background: linear-gradient(135deg, color-mix(in srgb, var(--cat-color) 12%, #fff), #fff);
    border: 1px solid #e2ebf5;
}
.popular-icon {
    width: 56px;
    height: 56px;
    border-radius: 12px;
    display: grid;
    place-items: center;
    background: color-mix(in srgb, var(--cat-color) 16%, #fff);
    color: var(--cat-color);
    font-size: 1.65rem;
    font-weight: 900;
}
.popular-calculator-card strong { display: block; line-height: 1.2; }
.popular-calculator-card small { display: block; color: #42526f; font-size: .84rem; line-height: 1.45; margin-top: 4px; }
.popular-calculator-card em { font-style: normal; font-size: 1.6rem; color: #082b65; }
.home-feature-strip {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    margin-top: 22px;
    padding: 18px 22px;
    background: #fff;
    border: 1px solid #dfe8f5;
    border-radius: 12px;
    box-shadow: 0 14px 34px rgba(15,23,42,.04);
}
.home-feature-strip div {
    display: grid;
    grid-template-columns: 48px 1fr;
    column-gap: 12px;
    align-items: center;
    padding: 0 14px;
    border-right: 1px solid #e5edf7;
}
.home-feature-strip div:last-child { border-right: 0; }
.home-feature-strip span {
    grid-row: span 2;
    width: 46px;
    height: 46px;
    border-radius: 50%;
    display: grid;
    place-items: center;
    color: #0b63f6;
    background: #eaf3ff;
    font-size: 1.35rem;
}
.home-feature-strip strong { line-height: 1.2; }
.home-feature-strip small { color: #42526f; }
.home-article-cta { display: flex; justify-content: center; gap: 14px; flex-wrap: wrap; }
.site-footer {
    background: linear-gradient(135deg, #071936 0%, #0d2445 100%);
    margin-top: 30px;
}
.footer-grid { grid-template-columns: 1.2fr .9fr .9fr 1fr; }
.footer-brand h2 { font-size: 1.65rem; }
.footer-bottom { background: rgba(0,0,0,.18); }
@media (max-width: 1100px) {
    .home-category-grid { grid-template-columns: repeat(3, 1fr); }
    .popular-calculator-grid { grid-template-columns: repeat(2, 1fr); }
    .home-feature-strip { grid-template-columns: repeat(2, 1fr); gap: 12px; }
    .home-feature-strip div { border-right: 0; }
}
@media (max-width: 900px) {
    .primary-menu a { padding: 12px 14px; }
    .primary-menu a:after { display: none; }
    .home-hero-card { grid-template-columns: 1fr; }
    .home-hero-art { min-height: 220px; }
    .site-account-area { margin-left: auto; }
}
@media (max-width: 640px) {
    .calchub-home-hero { padding-top: 16px; }
    .home-hero-card { border-radius: 16px; padding: 26px 18px; }
    .home-hero-copy h1 { font-size: 3rem; }
    .home-search { grid-template-columns: 40px 1fr; }
    .home-search button { grid-column: 1 / -1; min-height: 48px; }
    .home-category-grid,
    .popular-calculator-grid,
    .home-feature-strip { grid-template-columns: 1fr; }
    .home-section-row { align-items: flex-start; }
    .floating-ops { margin-right: 16px; gap: 10px; }
    .op { width: 40px; height: 40px; font-size: 1.45rem; }
    .big-calculator { width: 185px; padding: 14px; }
    .calc-keys span { min-height: 32px; }
    .site-account-area a, .calchub-account-link { padding: 10px 12px; font-size: .88rem; }
}