:root {
    --bg: #f4f6f9;
    --surface: #ffffff;
    --text: #1a1f36;
    --muted: #6b7280;
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --border: #e5e7eb;
    --radius: 12px;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
}

* { box-sizing: border-box; }

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

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1rem;
}

.header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 10;
}

.header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 64px;
}

.logo {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary);
    text-decoration: none;
}

.nav a {
    margin-left: 1rem;
    color: var(--muted);
    text-decoration: none;
}

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

.main { padding: 2rem 1rem 4rem; }

.hero { margin-bottom: 2rem; }

.lead { color: var(--muted); font-size: 1.1rem; }

.picker {
    display: grid;
    gap: 1rem;
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 2.5rem;
}

.picker label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.35rem;
}

.picker select {
    width: 100%;
    padding: 0.65rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    background: #fff;
}

.btn {
    padding: 0.75rem 1.25rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
}

.btn-primary {
    background: var(--primary);
    color: #fff;
}

.btn-primary:hover:not(:disabled) { background: var(--primary-hover); }

.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 1rem;
}

.card {
    display: block;
    background: var(--surface);
    padding: 1rem 1.25rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    text-decoration: none;
    color: inherit;
    transition: transform 0.15s, box-shadow 0.15s;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
}

.muted { color: var(--muted); font-size: 0.9rem; display: block; }

.breadcrumbs {
    margin-bottom: 1rem;
    font-size: 0.9rem;
    color: var(--muted);
}

.breadcrumbs a { color: var(--primary); text-decoration: none; }

.table {
    width: 100%;
    border-collapse: collapse;
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.table th,
.table td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border);
    text-align: left;
}

.table th {
    width: 35%;
    background: #f9fafb;
    color: var(--muted);
}

.seo-answer,
.engine-about,
.specs,
.recommendations,
.seo-text,
.faq,
.related-links { margin-top: 2rem; }

.seo-answer,
.seo-text,
.related-links {
    background: var(--surface);
    padding: 1.25rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.spec-grid,
.related-columns {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.oil-list { display: grid; gap: 1rem; }

.oil-card {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--surface);
    padding: 1rem 1.25rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.oil-card__rank {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    min-width: 2.5rem;
}

.oil-card__body { flex: 1; }

.oil-card__body h3 { margin: 0 0 0.25rem; font-size: 1.05rem; }

.tech-note {
    margin: 0.75rem 0 0;
    color: var(--text);
    font-size: 0.95rem;
}

.oil-card__score {
    font-weight: 700;
    color: #059669;
    font-size: 1.1rem;
}

.confidence-label {
    margin: 0.5rem 0 0;
    font-weight: 600;
    color: var(--primary);
}

.score-note {
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.match-breakdown {
    margin-top: 0.75rem;
    font-size: 0.95rem;
}

.match-breakdown p {
    margin: 0.5rem 0 0.25rem;
}

.match-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.match-list--ok li { color: #059669; }
.match-list--bad li { color: #dc2626; }

.viscosity-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.viscosity-tags .tag,
.tag {
    display: inline-block;
    padding: 0.35rem 0.75rem;
    background: var(--surface);
    border-radius: 999px;
    font-weight: 600;
    box-shadow: var(--shadow);
}

.engine-links {
    list-style: none;
    padding: 0.5rem 0 0;
    margin: 0;
}

.engine-links li { margin: 0.25rem 0; }

.tags {
    list-style: none;
    padding: 0;
    margin: 0.5rem 0 0;
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
}

.tags li {
    background: #eff6ff;
    color: var(--primary);
    padding: 0.2rem 0.5rem;
    border-radius: 6px;
    font-size: 0.8rem;
}

.faq details {
    background: var(--surface);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    margin-bottom: 0.5rem;
    box-shadow: var(--shadow);
}

.related-links h3 {
    margin-bottom: 0.5rem;
}

.related-links ul {
    margin: 0;
    padding-left: 1.1rem;
}

.related-links a {
    color: var(--primary);
    text-decoration: none;
}

.footer {
    border-top: 1px solid var(--border);
    padding: 1.5rem 0;
    color: var(--muted);
    font-size: 0.9rem;
    background: var(--surface);
}

.note {
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: #fffbeb;
    border-radius: 8px;
    color: #92400e;
}

@media (min-width: 640px) {
    .picker {
        grid-template-columns: 1fr 1fr;
    }
    .picker .btn-primary {
        grid-column: 1 / -1;
    }
}