:root {
    --ink: #14181f;
    --ink-dim: #5b6472;
    --line: #d7dbe1;
    --line-soft: #ebedf0;
    --bg: #ffffff;
    --bg-alt: #fafbfc;
    --accent: #0a5c9e;
    --warn-line: #b8860b;
    --warn-bg: #fdfaf2;
    --mono: ui-monospace, "SF Mono", "Roboto Mono", Consolas, monospace;
    --sans: -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
    --risk-low: #1a7a44;
    --risk-mod: #b8860b;
    --risk-high: #a4272c;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    height: 100%;
    font-family: var(--sans);
    background: var(--bg);
    color: var(--ink);
    font-size: 14px;
    line-height: 1.45;
}

header {
    border-bottom: 1px solid var(--line);
    padding: 14px 24px;
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 10px;
}

header .wordmark {
    font-weight: 700;
    font-size: 15px;
    letter-spacing: 0.02em;
}

header .wordmark span { color: var(--accent); }

header .tag { font-size: 12px; color: var(--ink-dim); }

.tag {
    display: inline-block;
    padding: 2px 8px;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    font-weight: 700;
    border: 1px solid currentColor;
    font-family: var(--sans);
}

.layout {
    display: grid;
    grid-template-columns: 260px 1fr;
    max-width: 1180px;
    margin: 0 auto;
    min-height: calc(100vh - 55px);
}

/* ---------- sidebar ---------- */

.sidebar {
    border-right: 1px solid var(--line);
    padding: 16px 0 40px;
}

.sidebar-search {
    padding: 0 16px 12px;
    border-bottom: 1px solid var(--line);
    margin-bottom: 6px;
}

.sidebar-search input {
    width: 100%;
    padding: 8px 10px;
    border: 1px solid var(--line);
    font-size: 13px;
    font-family: var(--sans);
    outline: none;
    background: var(--bg-alt);
    color: var(--ink);
}

.sidebar-search input:focus { border-color: var(--accent); }

.cat-block { margin-bottom: 4px; }

.cat-title {
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 700;
    color: var(--ink-dim);
    padding: 10px 16px 4px;
}

.calc-link {
    display: block;
    padding: 7px 16px;
    font-size: 13px;
    color: var(--ink);
    text-decoration: none;
    border-left: 2px solid transparent;
    cursor: pointer;
}

.calc-link:hover {
    background: var(--bg-alt);
}

.calc-link.active {
    border-left: 2px solid var(--accent);
    background: var(--bg-alt);
    font-weight: 600;
    color: var(--accent);
}

.calc-link.hidden { display: none; }
.cat-block.hidden { display: none; }

/* ---------- main panel ---------- */

.panel {
    padding: 24px 28px 60px;
    min-width: 0;
}

.panel-empty {
    color: var(--ink-dim);
    font-size: 13px;
    padding-top: 40px;
    text-align: center;
}

.calc-head {
    border-bottom: 2px solid var(--ink);
    padding-bottom: 10px;
    margin-bottom: 18px;
}

.calc-head .cat-eyebrow {
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--ink-dim);
    font-weight: 700;
}

.calc-head h2 {
    margin: 4px 0 0;
    font-size: 20px;
    font-weight: 700;
}

.field-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px 16px;
    margin-bottom: 20px;
}

.field-grid.single { grid-template-columns: 1fr; max-width: 420px; }

.field {
    border: 1px solid var(--line);
    padding: 8px 10px;
    background: var(--bg);
}

.field label {
    display: block;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--ink-dim);
    font-weight: 600;
    margin-bottom: 5px;
}

.field input[type="number"],
.field input[type="text"],
.field input[type="date"],
.field select {
    width: 100%;
    border: none;
    outline: none;
    font-family: var(--mono);
    font-size: 14px;
    color: var(--ink);
    background: transparent;
    padding: 0;
}

.field select { font-family: var(--sans); font-size: 13px; }

.field.checkfield {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
}

.field.checkfield label {
    margin: 0;
    text-transform: none;
    letter-spacing: 0;
    font-weight: 400;
    font-size: 13px;
    color: var(--ink);
    cursor: pointer;
}

.field.checkfield input[type="checkbox"] {
    width: 15px;
    height: 15px;
    accent-color: var(--accent);
    cursor: pointer;
}

.result-box {
    border: 1px solid var(--ink);
    padding: 16px 18px;
    margin-bottom: 18px;
    background: var(--bg-alt);
}

.result-box .r-value {
    font-family: var(--mono);
    font-size: 26px;
    font-weight: 700;
    color: var(--ink);
}

.result-box .r-unit {
    font-size: 13px;
    color: var(--ink-dim);
    margin-left: 6px;
}

.result-box .r-tag {
    display: inline-block;
    margin-top: 8px;
    padding: 3px 9px;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    font-weight: 700;
    border: 1px solid currentColor;
}

.r-tag.low { color: var(--risk-low); }
.r-tag.moderate { color: var(--risk-mod); }
.r-tag.high { color: var(--risk-high); }
.r-tag.neutral { color: var(--ink-dim); }

.result-box .r-note {
    margin-top: 8px;
    font-size: 12.5px;
    color: var(--ink-dim);
    line-height: 1.5;
}

.formula-note {
    font-size: 11px;
    font-family: var(--mono);
    color: var(--ink-dim);
    border-top: 1px solid var(--line);
    padding-top: 10px;
    white-space: pre-wrap;
}

.disclaimer {
    border: 1px solid var(--warn-line);
    background: var(--warn-bg);
    padding: 12px 14px;
    font-size: 12px;
    line-height: 1.5;
    margin-top: 22px;
}

.disclaimer strong {
    display: block;
    margin-bottom: 4px;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

@media (max-width: 800px) {
    .layout { grid-template-columns: 1fr; }
    .sidebar {
        border-right: none;
        border-bottom: 1px solid var(--line);
        max-height: 280px;
        overflow-y: auto;
    }
    .field-grid { grid-template-columns: 1fr; }
}