:root {
    --bg: #f6f7f9;
    --surface: #ffffff;
    --surface-alt: #eef6f3;
    --text: #18202a;
    --muted: #667085;
    --border: #d8dee8;
    --brand: #0f766e;
    --brand-dark: #0b4f4a;
    --accent: #b45309;
    --danger: #b42318;
    --radius: 8px;
    --shadow: 0 10px 25px rgba(24, 32, 42, 0.08);
}

* { box-sizing: border-box; }
html { color-scheme: light; }
body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.55;
}
a { color: var(--brand-dark); }
a:focus-visible, button:focus-visible, input:focus-visible {
    outline: 3px solid rgba(15, 118, 110, 0.35);
    outline-offset: 2px;
}
.site-header, .site-footer {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 1rem clamp(1rem, 4vw, 3rem);
}
.site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}
.brand {
    color: var(--text);
    display: inline-flex;
    align-items: center;
    gap: .75rem;
    text-decoration: none;
}
.brand-mark {
    align-items: center;
    background: var(--brand);
    border-radius: 7px;
    color: white;
    display: inline-flex;
    font-weight: 800;
    height: 2.5rem;
    justify-content: center;
    width: 2.5rem;
}
.brand small { color: var(--muted); display: block; }
.site-nav, .site-footer nav {
    display: flex;
    flex-wrap: wrap;
    gap: .75rem 1rem;
}
.site-nav a, .site-footer a { text-decoration: none; font-weight: 650; }
.page-shell {
    margin: 0 auto;
    max-width: 1180px;
    padding: clamp(1rem, 4vw, 3rem);
}
.hero {
    display: grid;
    gap: 1rem;
    padding: clamp(1.5rem, 5vw, 4rem) 0;
}
.hero.compact { padding: 1.5rem 0 2rem; }
.hero h1 {
    font-size: clamp(2rem, 6vw, 4.4rem);
    line-height: 1.02;
    margin: 0;
    max-width: 900px;
}
.hero p { font-size: 1.1rem; max-width: 760px; margin: 0; color: var(--muted); }
.eyebrow {
    color: var(--accent);
    font-size: .85rem;
    font-weight: 800;
    letter-spacing: 0;
    text-transform: uppercase;
}
.search-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    display: grid;
    gap: .75rem;
    max-width: 760px;
    padding: 1rem;
}
.search-panel label { font-weight: 750; }
.search-panel input {
    border: 1px solid var(--border);
    border-radius: 6px;
    font: inherit;
    min-height: 48px;
    padding: .8rem 1rem;
    width: 100%;
}
.category-grid, .list-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}
.card, .mini-card, .side-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
}
.card h2, .mini-card h3 { margin-top: 0; }
.card p, .mini-card p { color: var(--muted); }
.status-pill {
    background: var(--surface-alt);
    border-radius: 999px;
    color: var(--brand-dark);
    display: inline-flex;
    font-size: .8rem;
    font-weight: 750;
    padding: .2rem .55rem;
}
.content-grid {
    display: grid;
    gap: 1.25rem;
    grid-template-columns: minmax(0, 1fr);
}
.side-panel { align-self: start; }
.breadcrumbs ol {
    display: flex;
    flex-wrap: wrap;
    gap: .4rem;
    list-style: none;
    padding: 0;
}
.breadcrumbs li:not(:last-child)::after {
    color: var(--muted);
    content: "/";
    margin-left: .4rem;
}
.muted { color: var(--muted); }
.calculator-hero {
    display: grid;
    gap: 1rem;
    padding: 1.5rem 0;
}
.calculator-hero h1 {
    font-size: clamp(2rem, 6vw, 3.5rem);
    line-height: 1.05;
    margin: 0;
}
.calculator-hero p { color: var(--muted); max-width: 760px; }
.calculator-layout {
    align-items: start;
    display: grid;
    gap: 1rem;
    grid-template-columns: minmax(0, 1fr);
    margin-bottom: 2rem;
}
.calculator-card, .result-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1rem;
}
.mode-grid {
    border: 0;
    display: grid;
    gap: .6rem;
    margin: 0 0 1rem;
    padding: 0;
}
.mode-grid legend {
    font-weight: 800;
    margin-bottom: .5rem;
}
.mode-grid label {
    align-items: center;
    border: 1px solid var(--border);
    border-radius: 7px;
    cursor: pointer;
    display: flex;
    gap: .55rem;
    min-height: 44px;
    padding: .65rem .75rem;
}
.form-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: 1fr;
}
.form-grid label {
    display: grid;
    gap: .35rem;
    font-weight: 750;
}
.form-grid input,
.form-grid select,
.form-grid textarea {
    border: 1px solid var(--border);
    border-radius: 6px;
    font: inherit;
    min-height: 48px;
    padding: .75rem .85rem;
    width: 100%;
}
.form-grid textarea { resize: vertical; }
.wide-field { grid-column: 1 / -1; }
.category-scale {
    display: grid;
    gap: .35rem;
    margin-top: 1rem;
}
.category-scale span {
    border: 1px solid var(--border);
    border-radius: 6px;
    display: block;
    padding: .45rem .6rem;
}
.category-scale .active {
    background: var(--brand);
    border-color: var(--brand);
    color: white;
    font-weight: 800;
}
.form-grid small {
    color: var(--muted);
    font-weight: 500;
}
.button-row {
    display: flex;
    flex-wrap: wrap;
    gap: .6rem;
    margin-top: 1rem;
}
button {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text);
    cursor: pointer;
    font: inherit;
    font-weight: 750;
    min-height: 44px;
    padding: .7rem .9rem;
}
.primary-button {
    background: var(--brand);
    border-color: var(--brand);
    color: white;
}
.form-message {
    color: var(--danger);
    font-weight: 700;
    margin-top: .75rem;
}
.result-main {
    font-size: clamp(1.35rem, 4vw, 2rem);
    font-weight: 850;
    line-height: 1.2;
    margin: .35rem 0 .75rem;
}
.formula-list {
    display: grid;
    gap: .75rem;
    margin: 1rem 0 0;
}
.formula-list div {
    background: var(--surface-alt);
    border-radius: 7px;
    padding: .75rem;
}
.formula-list dt {
    color: var(--muted);
    font-size: .85rem;
    font-weight: 800;
    text-transform: uppercase;
}
.formula-list dd {
    margin: .2rem 0 0;
    overflow-wrap: anywhere;
}
.notice {
    border-radius: 6px;
    margin: .75rem 0 0;
    padding: .65rem .75rem;
}
.warning {
    background: #fff7ed;
    border: 1px solid #fed7aa;
    color: #9a3412;
}
.prose {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
}
.prose details {
    border-top: 1px solid var(--border);
    padding: .75rem 0;
}
.prose summary {
    cursor: pointer;
    font-weight: 800;
}
.site-footer {
    border-bottom: 0;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}
@media (min-width: 860px) {
    .content-grid { grid-template-columns: minmax(0, 1fr) 300px; }
    .calculator-layout { grid-template-columns: minmax(0, 1.1fr) minmax(320px, .9fr); }
    .form-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .operation-field { grid-column: span 2; }
    .mode-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}