:root {
    --bg: #f7f9fc;
    --card: #ffffff;
    --text: #13223a;
    --muted: #5e6b80;
    --brand: #1666d3;
    --border: #dde3ed;
}
* { box-sizing: border-box; }
body { margin: 0; font-family: Arial, Helvetica, sans-serif; background: var(--bg); color: var(--text); }
.container { width: min(1160px, 94%); margin: 0 auto; }
.site-header { background: #fff; border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 20; }
.nav-wrap { display: flex; justify-content: space-between; align-items: center; padding: 14px 0; }
.logo { font-weight: 700; color: var(--text); text-decoration: none; }
.main-nav a, .footer-nav a { color: var(--muted); text-decoration: none; margin-left: 16px; }
.main-nav a:hover, .footer-nav a:hover { color: var(--brand); }
.menu-toggle { display: none; padding: 8px 12px; border-radius: 8px; border: 1px solid var(--border); background: #fff; }
.hero { padding: 48px 0 24px; }
.hero h1 { margin: 0 0 8px; font-size: clamp(1.6rem, 2.6vw, 2.3rem); }
.hero p { color: var(--muted); max-width: 800px; }
.btn { display: inline-block; margin-top: 8px; background: var(--brand); color: #fff; text-decoration: none; padding: 10px 16px; border-radius: 8px; }
.btn-small { padding: 8px 12px; font-size: 0.92rem; margin-right: 6px; }
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 14px; padding: 16px 0 34px; }
.card, .calc-box, .prose { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 16px; }
.calc-card { display: flex; flex-direction: column; gap: 8px; }
.card h2 { margin: 0 0 8px; font-size: 1.1rem; }
.card p { color: var(--muted); margin: 0 0 8px; }
.card a { color: var(--brand); text-decoration: none; font-weight: 600; }
.card-icon, .tool-icon { width: 68px; height: 68px; display: grid; place-items: center; border-radius: 12px; background: linear-gradient(180deg, #f8fbff, #e9f1ff); border: 1px solid #d6e3ff; }
.card-icon svg, .tool-icon svg { width: 54px; height: 54px; }
.tool-heading { display: flex; align-items: center; gap: 12px; }
.prose { margin-top: 14px; margin-bottom: 20px; }
.calc-box { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.calc-controls { display: grid; gap: 10px; }
.calc-controls label { display: grid; gap: 4px; font-size: 0.92rem; }
input, select, button { width: 100%; padding: 10px; border: 1px solid var(--border); border-radius: 8px; }
.result-main { font-size: 1.6rem; font-weight: 700; margin: 0 0 6px; }
.result-sub { color: var(--muted); margin: 0 0 10px; }
.visual { min-height: 80px; border: 1px dashed var(--border); border-radius: 10px; padding: 10px; display: flex; align-items: end; gap: 6px; }
.bucket { width: 20px; border-radius: 4px 4px 2px 2px; background: linear-gradient(180deg, #53a7ff, #1666d3); }
.block { width: 22px; height: 22px; border-radius: 4px; background: #7c8b9d; }
.tile-cell { width: 14px; height: 14px; border: 1px solid #c9d0dc; background: #ecf3ff; }
.result-actions { display: flex; gap: 8px; }
.result-actions button { cursor: pointer; background: #fff; }
.site-footer { background: #fff; border-top: 1px solid var(--border); padding: 24px 0; margin-top: 24px; }
.footer-grid { display: flex; justify-content: space-between; gap: 12px; align-items: center; }
.breadcrumbs { font-size: 0.86rem; color: var(--muted); margin-bottom: 8px; }
@media (max-width: 800px) {
    .calc-box { grid-template-columns: 1fr; }
    .menu-toggle { display: inline-block; }
    .main-nav { display: none; position: absolute; top: 58px; left: 3%; right: 3%; background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 10px; box-shadow: 0 10px 24px rgba(0,0,0,.08); }
    .main-nav.open { display: grid; gap: 6px; }
    .main-nav a { margin-left: 0; padding: 10px; border-radius: 8px; }
    .main-nav a:hover { background: #f4f8ff; }
    .footer-grid { flex-direction: column; align-items: flex-start; }
    .result-actions { flex-direction: column; }
    .btn { width: 100%; text-align: center; }
}