/* =========================================================
   justcalculate.it
   Global stylesheet + shared calculator UI system
   ========================================================= */

:root {
    --bg: #f7f7f5;
    --surface: #ffffff;
    --text: #111111;
    --muted: #6f6f6b;
    --line: #e4e4df;
    --accent: #111111;
    --max-width: 1120px;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.5;
}

a {
    color: inherit;
    text-decoration: none;
}

button,
input,
select,
textarea {
    font: inherit;
}

.container {
    width: min(calc(100% - 40px), var(--max-width));
    margin-inline: auto;
}


/* =========================================================
   SITE
   ========================================================= */

.site-header {
    position: sticky;
    top: 0;
    z-index: 10;
    border-bottom: 1px solid var(--line);
    background: rgba(247, 247, 245, .92);
    backdrop-filter: blur(12px);
}

.header-inner {
    min-height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.logo {
    font-size: 20px;
    font-weight: 800;
    letter-spacing: -.04em;
}

.logo span {
    font-weight: 400;
}

.main-nav {
    display: flex;
    gap: 24px;
    color: var(--muted);
    font-size: 14px;
}

.main-nav a:hover {
    color: var(--text);
}


/* =========================================================
   HOME
   ========================================================= */

.hero {
    padding: 104px 0 84px;
}

.eyebrow {
    margin: 30px 0 12px;
    color: var(--muted);
    font-size: 13px;
    font-weight: 700;
    letter-spacing: .14em;
    text-transform: uppercase;
}

.hero h1 {
    margin: 0;
    max-width: 700px;
    font-size: clamp(52px, 8vw, 92px);
    line-height: .95;
    letter-spacing: -.065em;
}

.hero-subtitle {
    margin: 24px 0 42px;
    color: var(--muted);
    font-size: clamp(20px, 3vw, 28px);
    letter-spacing: -.025em;
}

.search-wrap {
    max-width: 700px;
}

.search-input {
    width: 100%;
    min-height: 62px;
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 0 22px;
    outline: none;
    background: var(--surface);
    color: var(--text);
    font-size: 17px;
    box-shadow: 0 8px 30px rgba(0,0,0,.04);
}

.search-input:focus {
    border-color: #b8b8b2;
}

.section {
    padding: 80px 0;
}

.section-muted {
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    background: #f1f1ed;
}

.section-heading {
    display: flex;
    align-items: end;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 30px;
}

.section-heading h2 {
    margin: 0;
    font-size: 38px;
    letter-spacing: -.04em;
}

.result-count {
    color: var(--muted);
    font-size: 14px;
}

.calculator-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
}

.calculator-card {
    position: relative;
    min-height: 250px;
    padding: 28px;
    border: 1px solid var(--line);
    border-radius: 22px;
    background: var(--surface);
    transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.calculator-card:hover {
    transform: translateY(-3px);
    border-color: #c8c8c2;
    box-shadow: 0 16px 40px rgba(0,0,0,.07);
}

.calculator-card-icon {
    margin-bottom: 28px;
    font-size: 28px;
}

.calculator-card-category {
    color: var(--muted);
    font-size: 10px;
    font-weight: 700;
    letter-spacing: .13em;
}

.calculator-card h3 {
    margin: 7px 0 8px;
    font-size: 24px;
    letter-spacing: -.035em;
}

.calculator-card p {
    max-width: 520px;
    margin: 0;
    color: var(--muted);
}


/* =========================================================
   CATEGORY FILTER
   ========================================================= */

.category-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 28px;
}

.category-button {
    appearance: none;
    border: 1px solid var(--line);
    border-radius: 999px;
    background: var(--surface);
    color: var(--text);
    padding: 8px 13px;
    display: inline-flex;
    align-items: center;
    gap: 7px;
    font-size: 14px;
    line-height: 1;
    cursor: pointer;
    transition: background .18s ease, border-color .18s ease, color .18s ease, transform .18s ease;
}

.category-button:hover {
    border-color: #aaa;
    transform: translateY(-1px);
}

.category-button.active {
    background: var(--text);
    border-color: var(--text);
    color: var(--bg);
}

.category-button span {
    min-width: 18px;
    height: 18px;
    padding-inline: 4px;
    border-radius: 999px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: rgba(0,0,0,.07);
    font-size: 11px;
    font-weight: 700;
}

.category-button.active span {
    background: rgba(255,255,255,.16);
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 12px;
}

.category-card {
    min-height: 120px;
    padding: 22px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: var(--surface);
    text-align: left;
    cursor: pointer;
    transition: transform .18s ease, border-color .18s ease;
}

.category-card:hover,
.category-card.is-active {
    transform: translateY(-2px);
    border-color: #aaa;
}

.category-card span,
.category-card small {
    display: block;
}

.category-card span {
    font-weight: 700;
}

.category-card small {
    margin-top: 8px;
    color: var(--muted);
}


/* =========================================================
   CALCULATOR PAGE
   ========================================================= */

.calculator-page {
    padding: 55px 0 90px;
}

.calculator-container {
    max-width: 900px;
}

.back-link {
    color: var(--muted);
    font-size: 14px;
}




/* =========================================================
   SHARED CALCULATOR UI
   These classes are the site's reusable calculator design system.
   ========================================================= */

.ui-demo {
    padding-bottom: 40px;
}

.ui-demo-section {
    margin-top: 64px;
}

.ui-demo-section:first-child {
    margin-top: 0;
}

.ui-demo-heading {
    margin-bottom: 20px;
}

.ui-demo-heading > span {
    display: block;
    margin-bottom: 7px;
    color: var(--muted);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: .14em;
}

.ui-demo-heading h2 {
    margin: 0;
    font-size: clamp(28px, 4vw, 38px);
    letter-spacing: -.045em;
}

.ui-demo-heading p {
    margin: 8px 0 0;
    color: var(--muted);
}

.ui-card,
.ui-result,
.ui-info,
.ui-warning,
.ui-formula,
.ui-empty-result {
    border: 1px solid var(--line);
    border-radius: 20px;
    background: var(--surface);
}

.ui-card {
    padding: 28px;
    margin-top: 15px;
}


/* Grids */

.ui-grid {
    display: grid;
    gap: 16px;
}

.ui-grid-2 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    margin-top: 14px;
}

.ui-grid-3 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    margin-top: 14px;
}


/* Fields */

.ui-field label {
    display: block;
    margin-top: 15px;
    margin-bottom: 8px;
    font-size: 13px;
    font-weight: 700;
}

.ui-field small {
    display: block;
    margin-top: 7px;
    color: var(--muted);
    font-size: 12px;
}

.ui-field input,
.ui-field select,
.ui-field textarea {
    width: 100%;
    min-height: 52px;
    padding: 0 14px;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: #fff;
    color: var(--text);
    font: inherit;
}

.ui-field input:focus,
.ui-field select:focus,
.ui-field textarea:focus {
    outline: 2px solid rgba(0,0,0,.12);
    outline-offset: 1px;
}

.ui-field input:disabled,
.ui-field select:disabled,
.ui-field textarea:disabled {
    background: #f2f2ef;
    color: var(--muted);
}

.ui-unit-input {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: #fff;
}

.ui-unit-input input {
    min-width: 0;
    border: 0;
    border-radius: 0;
}

.ui-unit-input input:focus {
    outline: none;
}

.ui-unit-input > span {
    display: flex;
    align-items: center;
    padding: 0 16px;
    border-left: 1px solid var(--line);
    color: var(--muted);
}


/* Options */

.ui-option-group {
    margin-top: 26px;
    padding-top: 22px;
    border-top: 1px solid var(--line);
}

.ui-option-group > strong {
    display: block;
    margin-bottom: 12px;
    font-size: 13px;
}

.ui-option-group label {
    display: block;
    margin-top: 11px;
    font-size: 14px;
}

.ui-option-group input {
    margin-right: 8px;
}


/* Buttons */

.ui-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.ui-btn {
    min-height: 48px;
    padding: 0 20px;
    border: 1px solid transparent;
    border-radius: 12px;
    font: inherit;
    font-weight: 700;
    cursor: pointer;
}

.ui-btn-primary {
    background: #111;
    color: #fff;
}

.ui-btn-secondary {
    border-color: var(--line);
    background: #fff;
    color: var(--text);
}

.ui-btn-ghost {
    background: transparent;
    color: var(--text);
}

.ui-btn:disabled {
    cursor: not-allowed;
    opacity: .4;
}


/* Results */

.ui-result {
    padding: 26px;
    margin-top: 8px;
}

.ui-result > span,
.ui-result-main > span,
.ui-empty-result > span {
    display: block;
    color: var(--muted);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: .13em;
}

.ui-result strong {
    display: block;
    margin-top: 8px;
    font-size: 30px;
    letter-spacing: -.03em;
}

.ui-result small {
    color: var(--muted);
}

.ui-result-main {
    margin-bottom: 14px;
    padding: 32px;
}

.ui-result-main strong {
    font-size: clamp(38px, 7vw, 60px);
    letter-spacing: -.05em;
}

.ui-result-main p {
    margin: 9px 0 0;
    color: var(--muted);
}


/* Information */

.ui-info,
.ui-warning {
    padding: 16px 28px;
}

.ui-info strong,
.ui-warning strong {
    display: block;
}

.ui-info p,
.ui-warning p {
    margin: 4px 0 4px;
    color: var(--muted);
    line-height: 1.65;
}

.ui-warning {
    margin-top: 12px;
    background: #faf7f0;
    border-color: #ded6c7;
}


/* Formula */

.ui-formula {
    padding: 5px 40px 5px 40px;
    margin: 5px 0 5px 0;
}

.ui-formula > span {
    color: var(--muted);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: .13em;
}

.ui-formula-equation {
    margin: 18px 0;
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: clamp(20px, 4vw, 25px);
}

.ui-formula p {
    margin: 0;
    color: var(--muted);
}


/* Tables */

.ui-table-wrap {
    overflow-x: auto;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: #fff;
}

.ui-table {
    width: 100%;
    min-width: 500px;
    border-collapse: collapse;
}

.ui-table th,
.ui-table td {
    padding: 16px 18px;
    border-bottom: 1px solid var(--line);
    text-align: left;
}

.ui-table th {
    background: #f3f3ef;
    color: var(--muted);
    font-size: 12px;
}

.ui-table tr:last-child td {
    border-bottom: 0;
}


/* Empty state */

.ui-empty-result {
    padding: 34px;
    text-align: center;
}

.ui-empty-result strong {
    display: block;
    margin-top: 10px;
    font-size: 48px;
}

.ui-empty-result p {
    margin: 5px 0 0;
    color: var(--muted);
}


/* =========================================================
   SEO / FAQ
   ========================================================= */

.seo-content {
    margin-top: 72px;
}



.ui-card h2 {
    margin: 0 0 8px;
}

.seo-content-section p {
    margin: 0;
    color: var(--muted);
    line-height: 1.7;
}

.seo-faq {
    margin-top: 72px;
}

.seo-faq-head {
    margin-bottom: 22px;
}

.faq-list {
    display: grid;
    gap: 12px;
}

.faq-item {
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: var(--surface);
}

.faq-item summary {
    cursor: pointer;
    padding: 20px 22px;
    font-weight: 700;
    list-style: none;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item p {
    margin: 0;
    padding: 0 22px 20px;
    color: var(--muted);
    line-height: 1.65;
}


/* =========================================================
   FOOTER / UTILITIES
   ========================================================= */

.empty-state {
    padding: 50px 20px;
    text-align: center;
}

.empty-state h3 {
    margin: 0 0 6px;
}

.empty-state p {
    margin: 0;
    color: var(--muted);
}

.site-footer {
    padding: 50px 0;
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    gap: 30px;
    color: var(--muted);
}

.footer-inner p {
    margin: 8px 0 0;
    font-size: 14px;
}

.footer-meta {
    align-self: end;
    font-size: 13px;
}

.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;
}

[hidden] {
    display: none !important;
}


/* =========================================================
   RESPONSIVE
   ========================================================= */

@media (max-width: 760px) {

    .container {
        width: min(calc(100% - 28px), var(--max-width));
    }

    .main-nav {
        display: none;
    }

    .hero {
        padding: 72px 0 56px;
    }

    .calculator-grid,
    .category-grid {
        grid-template-columns: 1fr;
    }

    .section {
        padding: 58px 0;
    }

    .section-heading {
        align-items: start;
        flex-direction: column;
    }

    .footer-inner {
        flex-direction: column;
    }

    .calculator-page {
        padding-top: 35px;
    }

    .calculator-intro {
        margin-top: 48px;
    }

    .ui-grid-2,
    .ui-grid-3 {
        grid-template-columns: 1fr;
    }

    .ui-card,
    .ui-result,
    .ui-info,
    .ui-warning,
    .ui-formula,
    .ui-empty-result {
        padding: 20px;
    }

    .ui-result-main {
        padding: 24px;
    }

    .ui-buttons {
        flex-direction: column;
    }

    .ui-btn {
        width: 100%;
    }

    .category-list {
        gap: 6px;
    }

    .category-button {
        font-size: 13px;
        padding: 7px 11px;
    }
}