/* =============================================================
   DataTransferCalculator — Full CSS
   Modern, responsive, ads-ready
   ============================================================= */

/* ---------- Reset ---------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    scroll-padding-top: 80px;
    overflow-x: hidden;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #1e293b;
    background: #f8fafc;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    max-width: 100%;
}

img, svg { max-width: 100%; height: auto; display: block; }

/* ---------- Variables ---------- */
:root {
    --blue: #2563eb;
    --blue-dark: #1d4ed8;
    --blue-light: #eff6ff;
    --blue-border: #bfdbfe;
    --green: #16a34a;
    --red: #dc2626;
    --text: #1e293b;
    --text-light: #64748b;
    --text-lighter: #94a3b8;
    --bg: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
    --border-dark: #cbd5e1;
    --radius: 10px;
    --radius-lg: 14px;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.05), 0 2px 4px rgba(0, 0, 0, 0.04);
    --gutter: 10%;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 {
    line-height: 1.3;
    font-weight: 700;
    color: var(--text);
    letter-spacing: -0.02em;
}

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; margin-bottom: 16px; }
h3 { font-size: 1.15rem; margin-bottom: 12px; }
h4 { font-size: 1rem; margin-bottom: 8px; }

p { color: #334155; margin-bottom: 12px; }
p:last-child { margin-bottom: 0; }

a { color: var(--blue); text-decoration: none; }
a:hover { color: var(--blue-dark); text-decoration: underline; }

ul, ol { padding-left: 20px; color: #334155; }
li { margin-bottom: 6px; }

strong { color: var(--text); font-weight: 600; }

::selection { background: var(--blue-border); color: var(--text); }

:focus { outline: none; }
:focus-visible {
    outline: 2px solid var(--blue);
    outline-offset: 2px;
    border-radius: 4px;
}

/* ---------- Layout ---------- */
.container {
    width: 100%;
    margin: 0 auto;
    padding-left: var(--gutter);
    padding-right: var(--gutter);
}

main { min-height: 60vh; padding-bottom: 40px; }

.skip-link {
    position: absolute;
    left: -9999px;
    top: 0;
    background: var(--blue);
    color: #fff;
    padding: 10px 16px;
    z-index: 999;
    border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; color: #fff; text-decoration: none; }

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

/* ---------- Header ---------- */
.site-header {
    background: var(--white);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}

.header-inner {
    display: flex;
    align-items: center;
    gap: 16px;
    min-height: 64px;
    padding: 10px var(--gutter);
    position: relative;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 1.15rem;
    color: var(--text);
    flex-shrink: 0;
}
.logo:hover { color: var(--blue); text-decoration: none; }
.logo svg { color: var(--blue); flex-shrink: 0; }

.main-nav { display: flex; gap: 4px; margin-left: 20px; }
.main-nav a {
    display: inline-flex;
    align-items: center;
    padding: 8px 14px;
    color: #475569;
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: 8px;
    text-decoration: none;
    transition: all 0.15s;
}
.main-nav a:hover {
    color: var(--blue);
    background: var(--blue-light);
    text-decoration: none;
}

.lang-switcher { margin-left: auto; }
.lang-switcher select {
    appearance: none;
    -webkit-appearance: none;
    padding: 8px 32px 8px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background-color: var(--white);
    color: var(--text);
    font-size: 0.9rem;
    font-family: inherit;
    cursor: pointer;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 10px center;
    transition: border-color 0.15s;
}
.lang-switcher select:hover { border-color: var(--border-dark); }
.lang-switcher select:focus { border-color: var(--blue); outline: none; }

.menu-toggle {
    display: none;
    width: 40px;
    height: 40px;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    cursor: pointer;
    transition: background 0.15s;
}
.menu-toggle:hover { background: var(--bg); }

/* ---------- Breadcrumb ---------- */
.breadcrumb {
    padding: 20px 0 8px;
    font-size: 0.875rem;
    color: var(--text-light);
}
.breadcrumb ol {
    list-style: none;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
}
.breadcrumb li { margin: 0; }
.breadcrumb li + li::before {
    content: "›";
    margin-right: 8px;
    color: var(--text-lighter);
}
.breadcrumb a { color: var(--text-light); }
.breadcrumb a:hover { color: var(--blue); }
.breadcrumb li[aria-current] { color: var(--text); font-weight: 500; }

/* ---------- Hero ---------- */
.hero { padding: 32px 0 24px; }
.hero h1 {
    font-size: 2rem;
    margin-bottom: 12px;
    font-weight: 800;
}
.hero p {
    font-size: 1.05rem;
    color: var(--text-light);
    max-width: 720px;
    line-height: 1.6;
    margin: 0;
}

@media (min-width: 768px) {
    .hero h1 { font-size: 2.4rem; }
}

/* ---------- Search ---------- */
.search-box {
    position: relative;
    margin: 24px 0;
    max-width: 640px;
}
.search-box input {
    width: 100%;
    padding: 14px 16px 14px 44px;
    font-size: 1rem;
    font-family: inherit;
    color: var(--text);
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: border-color 0.15s, box-shadow 0.15s;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='18' height='18' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Ccircle cx='11' cy='11' r='8'/%3E%3Cpath d='m21 21-4.3-4.3'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: 14px center;
}
.search-box input:focus {
    border-color: var(--blue);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
    outline: none;
}

.search-results {
    position: absolute;
    top: calc(100% + 4px);
    left: 0;
    right: 0;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    max-height: 320px;
    overflow-y: auto;
    z-index: 30;
    padding: 6px;
}
.search-results:empty { display: none; }
.search-results a {
    display: block;
    padding: 10px 14px;
    color: var(--text);
    border-radius: 6px;
    font-size: 0.95rem;
    text-decoration: none;
}
.search-results a:hover {
    background: var(--blue-light);
    color: var(--blue);
    text-decoration: none;
}

/* ---------- Converter Card ---------- */
.converter-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: 24px;
    margin: 24px 0 40px;
    border-top: 3px solid var(--blue);
}

.upload-header { margin-bottom: 16px; }

.upload-header-title {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text);
    margin: 0;
    letter-spacing: -0.01em;
}
.upload-header-title svg { color: var(--blue); flex-shrink: 0; }

.manual-section-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 18px;
}

/* Converter inputs */
.converter-row {
    display: grid;
    grid-template-columns: 1.4fr 1fr auto 1fr;
    gap: 12px;
    align-items: end;
}

.field {
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-width: 0;
}

.field label {
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--text-light);
}

.field input,
.field select {
    width: 100%;
    padding: 12px 14px;
    font-size: 0.95rem;
    font-family: inherit;
    color: var(--text);
    background: var(--white);
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    min-height: 46px;
    transition: border-color 0.15s, box-shadow 0.15s;
}

.field select {
    appearance: none;
    -webkit-appearance: none;
    padding-right: 38px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    cursor: pointer;
    text-overflow: ellipsis;
}

.field input:hover,
.field select:hover { border-color: var(--border-dark); }

.field input:focus,
.field select:focus {
    border-color: var(--blue);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
    outline: none;
}

.field input[aria-invalid="true"] {
    border-color: var(--red);
    background: #fef2f2;
}

.error {
    color: var(--red);
    font-size: 0.8rem;
    font-weight: 500;
    min-height: 1em;
}

/* Swap button */
.swap-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 46px;
    height: 46px;
    padding: 0;
    background: var(--white);
    border: 1.5px solid var(--border);
    border-radius: 50%;
    color: var(--text-light);
    cursor: pointer;
    margin-bottom: 1px;
    transition: all 0.2s;
}
.swap-btn:hover {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-light);
    transform: rotate(180deg);
}
.swap-btn:active { transform: rotate(180deg) scale(0.95); }

/* Result area */
.result-area {
    margin-top: 20px;
    padding: 20px;
    background: linear-gradient(135deg, #eff6ff 0%, #f0f9ff 100%);
    border: 1.5px solid var(--blue-border);
    border-radius: var(--radius-lg);
}

.result-label {
    display: block;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--blue);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 6px;
}

.result-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text);
    line-height: 1.3;
    word-break: break-word;
    font-variant-numeric: tabular-nums;
}

.result-details {
    margin-top: 14px;
    padding-top: 14px;
    border-top: 1px dashed var(--blue-border);
    display: grid;
    gap: 8px;
}

.detail-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    font-size: 0.95rem;
    align-items: baseline;
}
.detail-row > span:first-child {
    color: var(--text-light);
    min-width: 120px;
    font-weight: 500;
}
.detail-row strong {
    color: var(--text);
    font-weight: 600;
    word-break: break-word;
}

/* Quick chips */
.quick-chips-wrap {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
    margin-top: 16px;
    padding-top: 14px;
    border-top: 1px solid var(--blue-border);
}

.quick-label {
    font-size: 0.82rem;
    color: var(--text-light);
    font-weight: 500;
    flex-shrink: 0;
}

.quick-chips {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.quick-chips button {
    padding: 6px 12px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 999px;
    font-size: 0.78rem;
    font-weight: 500;
    color: var(--text);
    font-family: inherit;
    cursor: pointer;
    transition: all 0.15s;
    font-variant-numeric: tabular-nums;
    white-space: nowrap;
}
.quick-chips button:hover {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-light);
}

/* Formula bar */
.formula-bar {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 14px 18px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.88rem;
    flex-wrap: wrap;
    margin-top: 16px;
}

.formula-label {
    color: var(--text-light);
    font-weight: 500;
}

.formula-value {
    color: var(--text);
    font-weight: 600;
    font-variant-numeric: tabular-nums;
    font-family: ui-monospace, "SF Mono", Menlo, monospace;
    word-break: break-all;
}

/* Action buttons */
.action-row {
    display: flex;
    gap: 10px;
    margin-top: 16px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 11px 20px;
    font-size: 0.95rem;
    font-weight: 600;
    font-family: inherit;
    border: 1.5px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    min-height: 44px;
    transition: all 0.15s;
    text-decoration: none;
    white-space: nowrap;
}
.btn:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
.btn:active { transform: translateY(1px); }

.btn-primary {
    background: var(--blue);
    color: #fff;
}
.btn-primary:hover {
    background: var(--blue-dark);
    color: #fff;
    text-decoration: none;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
}

.btn-secondary {
    background: var(--white);
    color: var(--text);
    border-color: var(--border);
}
.btn-secondary:hover {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-light);
    text-decoration: none;
}

.btn.copied {
    background: var(--green);
    border-color: var(--green);
    color: #fff;
}

.btn-sm {
    padding: 8px 14px;
    font-size: 0.85rem;
    min-height: 38px;
}

/* ---------- Ad Slots ---------- */
.ad-slot {
    margin: 32px auto;
    width: 100%;
    max-width: 100%;
    text-align: center;
    min-height: 120px;
    display: block;
    position: relative;
    padding: 8px 0;
    overflow: hidden;
    clear: both;
}

.ad-slot[data-label]::before {
    content: attr(data-label);
    display: block;
    font-size: 0.68rem;
    color: var(--text-lighter);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    font-weight: 600;
    margin-bottom: 8px;
    text-align: center;
}

.ad-slot ins.adsbygoogle {
    display: block !important;
    width: 100% !important;
    max-width: 100% !important;
    min-height: 100px !important;
    margin: 0 auto !important;
    text-align: center;
}

.ad-slot iframe {
    max-width: 100% !important;
    display: block !important;
    margin: 0 auto !important;
    border: 0;
}

iframe[id^="aswift"],
iframe[name^="aswift"] {
    max-width: 100% !important;
}

/* ---------- Content Sections ---------- */
.content-section { margin: 40px 0; }
.content-section h2 {
    font-size: 1.5rem;
    margin-bottom: 16px;
    scroll-margin-top: 80px;
}
.content-section h3 {
    font-size: 1.1rem;
    margin-top: 24px;
    margin-bottom: 10px;
    scroll-margin-top: 80px;
}
.content-section p,
.content-section li {
    color: #334155;
    line-height: 1.7;
}

.formula-box {
    background: #f1f5f9;
    border-left: 4px solid var(--blue);
    padding: 16px 20px;
    border-radius: var(--radius);
    font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
    font-size: 0.9rem;
    margin: 16px 0;
    overflow-x: auto;
    color: var(--text);
}

/* ---------- Tables ---------- */
.table-wrap {
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--white);
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
    position: relative;
}
.table-wrap::-webkit-scrollbar { height: 8px; }
.table-wrap::-webkit-scrollbar-track { background: #f1f5f9; }
.table-wrap::-webkit-scrollbar-thumb { background: var(--border-dark); border-radius: 4px; }
.table-wrap::-webkit-scrollbar-thumb:hover { background: var(--text-lighter); }

table.conv-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
    min-width: 320px;
}

table.conv-table th,
table.conv-table td {
    padding: 12px 18px;
    text-align: left;
    border-bottom: 1px solid var(--border);
    white-space: nowrap;
    vertical-align: middle;
}

table.conv-table th {
    background: #f8fafc;
    font-weight: 600;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-light);
    position: sticky;
    top: 0;
    z-index: 1;
}

table.conv-table tr:last-child td { border-bottom: 0; }
table.conv-table tr:hover td { background: #f8fafc; }
table.conv-table td:last-child {
    text-align: right;
    font-weight: 600;
    color: var(--text);
    font-variant-numeric: tabular-nums;
}

/* ---------- FAQ ---------- */
.faq-list { display: grid; gap: 8px; }

.faq-item {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: border-color 0.15s;
}
.faq-item:hover { border-color: var(--border-dark); }
.faq-item[open] { border-color: var(--blue-border); }

.faq-item summary {
    padding: 16px 20px;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    color: var(--text);
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    user-select: none;
    transition: color 0.15s;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
    content: "+";
    flex-shrink: 0;
    font-size: 1.4rem;
    font-weight: 400;
    color: var(--blue);
    line-height: 1;
    transition: transform 0.2s;
}
.faq-item[open] summary::after { content: "−"; }
.faq-item:hover summary { color: var(--blue); }

.faq-item .faq-answer {
    padding: 0 20px 18px;
    color: #334155;
    font-size: 0.95rem;
    line-height: 1.7;
}

/* ---------- Tool Grid ---------- */
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 12px;
}

.tool-card {
    display: block;
    padding: 16px 18px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-weight: 600;
    font-size: 0.95rem;
    text-decoration: none;
    transition: all 0.15s;
    text-align: center;
}
.tool-card:hover {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-light);
    text-decoration: none;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.category-block {
    margin-bottom: 32px;
    scroll-margin-top: 80px;
}
.category-block h3 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-light);
    margin-bottom: 12px;
    font-weight: 700;
}

/* ---------- Related Tools ---------- */
.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 10px;
}

.related-grid a {
    display: block;
    padding: 12px 16px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-weight: 500;
    font-size: 0.9rem;
    text-align: center;
    text-decoration: none;
    transition: all 0.15s;
}
.related-grid a:hover {
    border-color: var(--blue);
    color: var(--blue);
    background: var(--blue-light);
    text-decoration: none;
}

/* ---------- TOC ---------- */
.toc {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
    margin: 24px 0;
    font-size: 0.95rem;
}

.toc-title {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-weight: 700;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text);
    margin-bottom: 10px;
    cursor: pointer;
    user-select: none;
    padding: 0;
    background: none;
    border: 0;
    width: 100%;
    text-align: left;
    font-family: inherit;
}
.toc-title::after {
    content: "";
    flex-shrink: 0;
    width: 16px;
    height: 16px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
    background-size: contain;
    background-repeat: no-repeat;
    transition: transform 0.2s;
    margin-left: auto;
}
.toc[data-open="true"] .toc-title::after {
    transform: rotate(180deg);
}

.toc-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: 4px;
}
.toc-list li { margin: 0; }
.toc-list a {
    display: block;
    padding: 6px 10px;
    border-radius: 6px;
    color: var(--text-light);
    text-decoration: none;
    font-size: 0.9rem;
    line-height: 1.4;
    border-left: 2px solid transparent;
    transition: all 0.15s;
}
.toc-list a:hover {
    color: var(--blue);
    background: var(--blue-light);
    border-left-color: var(--blue);
    text-decoration: none;
}

.toc-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.25s ease;
}
.toc[data-open="true"] .toc-body {
    max-height: 800px;
    transition: max-height 0.35s ease;
}

@media (min-width: 900px) {
    .toc-title { cursor: default; }
    .toc-title::after { display: none; }
    .toc-body {
        max-height: none !important;
        overflow: visible !important;
    }
}

/* ---------- Tool Layout (with TOC sidebar) ---------- */
.tool-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 40px;
    align-items: start;
}

@media (min-width: 1100px) {
    .tool-layout {
        grid-template-columns: minmax(0, 1fr) 240px;
    }
    .tool-sidebar {
        position: sticky;
        top: 88px;
        align-self: start;
    }
    .tool-sidebar .toc { margin: 0; }
}

@media (max-width: 1099px) {
    .tool-sidebar { order: -1; }
    .tool-sidebar .toc { margin: 16px 0; }
}

/* ---------- Footer ---------- */
.site-footer {
    margin-top: 64px;
    padding: 48px 0 24px;
    background: var(--white);
    border-top: 1px solid var(--border);
    color: var(--text-light);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 32px;
}

.footer-brand .logo { margin-bottom: 12px; }
.footer-brand p {
    font-size: 0.9rem;
    color: var(--text-light);
    max-width: 320px;
    line-height: 1.6;
}

.footer-col h3 {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text);
    margin-bottom: 14px;
    font-weight: 700;
}
.footer-col ul {
    list-style: none;
    padding: 0;
    display: grid;
    gap: 10px;
}
.footer-col li { margin: 0; }
.footer-col a {
    color: var(--text-light);
    font-size: 0.9rem;
    text-decoration: none;
}
.footer-col a:hover { color: var(--blue); }

.lang-list {
    grid-template-columns: repeat(2, 1fr) !important;
    gap: 8px 16px !important;
}

.footer-bottom {
    padding-top: 24px;
    border-top: 1px solid var(--border);
    font-size: 0.85rem;
    color: var(--text-lighter);
    text-align: center;
}

/* ---------- 404 ---------- */
.error-page {
    text-align: center;
    padding: 80px 20px;
}
.error-page h1 {
    font-size: 5rem;
    color: var(--blue);
    margin-bottom: 12px;
    line-height: 1;
    font-weight: 800;
}
.error-page p {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 24px;
}

/* ---------- Utilities ---------- */
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.text-center { text-align: center; }

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

/* Gutter adjustments */
@media (max-width: 1280px) { :root { --gutter: 6%; } }
@media (max-width: 1024px) { :root { --gutter: 5%; } }
@media (max-width: 768px)  { :root { --gutter: 20px; } }

/* Mobile navigation */
@media (max-width: 860px) {
    .menu-toggle { display: inline-flex; order: 3; }
    .lang-switcher { margin-left: auto; order: 2; }

    .main-nav {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        margin-left: 0;
        flex-direction: column;
        align-items: stretch;
        gap: 2px;
        padding: 12px var(--gutter);
        background: var(--white);
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-md);
        display: none;
    }
    .main-nav.open { display: flex; }
    .main-nav a {
        padding: 12px 14px;
        font-size: 1rem;
        border-radius: var(--radius);
    }
}

/* Tablet */
@media (max-width: 1024px) {
    .footer-grid { grid-template-columns: 1.5fr 1fr 1fr; }
    .footer-brand { grid-column: 1 / -1; }
}

/* Mobile */
@media (max-width: 768px) {
    h1, .hero h1 { font-size: 1.6rem; }
    h2 { font-size: 1.25rem; }
    h3 { font-size: 1.05rem; }

    .hero { padding: 24px 0 16px; }
    .hero p { font-size: 0.95rem; }

    .converter-card { padding: 18px; }
    .converter-row { grid-template-columns: 1fr; gap: 12px; }

    .swap-btn {
        justify-self: center;
        width: 100%;
        height: 44px;
        border-radius: var(--radius);
        margin: 0;
    }
    .swap-btn svg { transform: rotate(90deg); }
    .swap-btn:hover { transform: none; }
    .swap-btn:hover svg { transform: rotate(90deg); }

    .result-value { font-size: 1.2rem; }

    .detail-row { flex-direction: column; gap: 2px; }
    .detail-row > span:first-child {
        min-width: 0;
        font-size: 0.8rem;
        text-transform: uppercase;
        letter-spacing: 0.04em;
    }

    .action-row .btn { flex: 1 1 0; }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 32px;
    }
    .footer-brand { grid-column: 1 / -1; }
    .lang-list { grid-template-columns: repeat(2, 1fr) !important; }

    .ad-slot {
        margin: 20px auto;
        min-height: 100px;
        padding: 6px 0;
    }
    .ad-slot ins.adsbygoogle {
        min-height: 90px !important;
    }

    table.conv-table { font-size: 0.9rem; }
    table.conv-table th,
    table.conv-table td { padding: 10px 14px; }

    .quick-chips-wrap { gap: 8px; }
    .formula-bar {
        padding: 12px 14px;
        font-size: 0.82rem;
    }
}

/* Small mobile */
@media (max-width: 520px) {
    .logo { font-size: 1rem; }
    .lang-switcher select {
        padding: 7px 26px 7px 10px;
        font-size: 0.85rem;
    }

    .tool-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
    .tool-card { padding: 12px 10px; font-size: 0.85rem; }

    .related-grid { grid-template-columns: 1fr 1fr; }
    .related-grid a { padding: 10px 12px; font-size: 0.85rem; }

    .footer-grid { grid-template-columns: 1fr; gap: 28px; }
    .lang-list { grid-template-columns: repeat(3, 1fr) !important; }

    .breadcrumb { font-size: 0.8rem; }
    .error-page h1 { font-size: 4rem; }

    .ad-slot {
        margin-left: -12px;
        margin-right: -12px;
        width: calc(100% + 24px);
    }

    .table-wrap {
        margin-left: calc(-1 * (var(--gutter) - 12px));
        margin-right: calc(-1 * (var(--gutter) - 12px));
    }
    table.conv-table { font-size: 0.85rem; }
    table.conv-table th,
    table.conv-table td { padding: 10px 12px; }
    table.conv-table th { font-size: 0.7rem; }
}

/* Very small */
@media (max-width: 380px) {
    .tool-grid { grid-template-columns: 1fr; }
    .action-row { flex-direction: column; }
    .action-row .btn { width: 100%; }
}

/* ---------- Reduced Motion ---------- */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* ---------- Print ---------- */
@media print {
    .site-header, .site-footer, .ad-slot, .action-row,
    .swap-btn, .search-box, .lang-switcher, .menu-toggle {
        display: none !important;
    }
    body {
        background: #fff;
        color: #000;
        font-size: 12pt;
    }
    .container { padding: 0; }
    .converter-card, .result-area {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}