/* ============================================================
   Solar Arbitrage Calculator — Material 3 design system
   Theme-aware (light/dark), responsive, UIAx-aligned.
   ============================================================ */

:root {
  /* Material 3 tonal palette — primary (solar amber/green blend) */
  --md-primary: #386a20;
  --md-on-primary: #ffffff;
  --md-primary-container: #b7f397;
  --md-on-primary-container: #072100;
  --md-secondary: #55624c;
  --md-on-secondary: #ffffff;
  --md-secondary-container: #d9e7cb;
  --md-on-secondary-container: #131f0d;
  --md-tertiary: #386663;
  --md-tertiary-container: #bcece7;
  --md-on-tertiary-container: #00201e;
  --md-error: #ba1a1a;
  --md-on-error: #ffffff;
  --md-error-container: #ffdad6;
  --md-on-error-container: #410002;
  --md-warning: #7a5900;
  --md-warning-container: #ffdf9e;

  --md-surface: #fdfcf5;
  --md-surface-dim: #dddbd0;
  --md-surface-bright: #fdfcf5;
  --md-surface-container-lowest: #ffffff;
  --md-surface-container-low: #f7f6ee;
  --md-surface-container: #f1f0e8;
  --md-surface-container-high: #ebeae2;
  --md-surface-container-highest: #e6e4dc;
  --md-on-surface: #1a1c18;
  --md-on-surface-variant: #44483e;
  --md-outline: #74796d;
  --md-outline-variant: #c4c8ba;
  --md-inverse-surface: #2f312c;
  --md-inverse-on-surface: #f1f1e9;

  --md-success: #386a20;
  --shadow-1: 0 1px 3px rgba(0,0,0,.12), 0 1px 2px rgba(0,0,0,.08);
  --shadow-2: 0 3px 6px rgba(0,0,0,.15), 0 2px 4px rgba(0,0,0,.10);

  --radius-xs: 4px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 28px;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", system-ui, sans-serif;
  --mono: "SF Mono", ui-monospace, "Roboto Mono", Menlo, monospace;
}

:root[data-theme="dark"] {
  --md-primary: #9cd67d;
  --md-on-primary: #0d3900;
  --md-primary-container: #205200;
  --md-on-primary-container: #b7f397;
  --md-secondary: #bdcbaf;
  --md-on-secondary: #283420;
  --md-secondary-container: #3e4a35;
  --md-on-secondary-container: #d9e7cb;
  --md-tertiary: #a0d0cb;
  --md-tertiary-container: #1e4e4b;
  --md-on-tertiary-container: #bcece7;
  --md-error: #ffb4ab;
  --md-error-container: #93000a;
  --md-on-error-container: #ffdad6;
  --md-warning: #ffdf9e;
  --md-warning-container: #5c4300;

  --md-surface: #12140f;
  --md-surface-dim: #12140f;
  --md-surface-bright: #383a34;
  --md-surface-container-lowest: #0d0f0a;
  --md-surface-container-low: #1a1c18;
  --md-surface-container: #1e201b;
  --md-surface-container-high: #282b25;
  --md-surface-container-highest: #333530;
  --md-on-surface: #e2e3db;
  --md-on-surface-variant: #c4c8ba;
  --md-outline: #8e9285;
  --md-outline-variant: #44483e;
  --md-inverse-surface: #e2e3db;
  --md-inverse-on-surface: #2f312c;
  --shadow-1: 0 1px 3px rgba(0,0,0,.4), 0 1px 2px rgba(0,0,0,.3);
  --shadow-2: 0 3px 6px rgba(0,0,0,.5), 0 2px 4px rgba(0,0,0,.4);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --md-primary: #9cd67d; --md-on-primary: #0d3900;
    --md-primary-container: #205200; --md-on-primary-container: #b7f397;
    --md-secondary: #bdcbaf; --md-on-secondary: #283420;
    --md-secondary-container: #3e4a35; --md-on-secondary-container: #d9e7cb;
    --md-tertiary: #a0d0cb; --md-tertiary-container: #1e4e4b; --md-on-tertiary-container: #bcece7;
    --md-error: #ffb4ab; --md-error-container: #93000a; --md-on-error-container: #ffdad6;
    --md-warning: #ffdf9e; --md-warning-container: #5c4300;
    --md-surface: #12140f; --md-surface-dim: #12140f; --md-surface-bright: #383a34;
    --md-surface-container-lowest: #0d0f0a; --md-surface-container-low: #1a1c18;
    --md-surface-container: #1e201b; --md-surface-container-high: #282b25;
    --md-surface-container-highest: #333530;
    --md-on-surface: #e2e3db; --md-on-surface-variant: #c4c8ba;
    --md-outline: #8e9285; --md-outline-variant: #44483e;
    --md-inverse-surface: #e2e3db; --md-inverse-on-surface: #2f312c;
    --shadow-1: 0 1px 3px rgba(0,0,0,.4), 0 1px 2px rgba(0,0,0,.3);
    --shadow-2: 0 3px 6px rgba(0,0,0,.5), 0 2px 4px rgba(0,0,0,.4);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--md-surface);
  color: var(--md-on-surface);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* ---------- App bar ---------- */
.app-bar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; gap: 12px;
  padding: 10px 16px;
  background: var(--md-surface-container);
  border-bottom: 1px solid var(--md-outline-variant);
  backdrop-filter: saturate(1.2) blur(8px);
}
.app-bar .logo {
  width: 36px; height: 36px; border-radius: 10px;
  display: grid; place-items: center;
  background: var(--md-primary-container); color: var(--md-on-primary-container);
  font-size: 20px; flex: none;
}
.app-bar h1 { font-size: 1.05rem; margin: 0; font-weight: 600; letter-spacing: .2px; }
.app-bar .sub { font-size: .72rem; color: var(--md-on-surface-variant); margin: 0; }
.app-bar .spacer { flex: 1; }
.icon-btn {
  width: 42px; height: 42px; border-radius: 50%;
  border: none; background: transparent; color: var(--md-on-surface-variant);
  font-size: 20px; cursor: pointer; display: grid; place-items: center;
  transition: background .15s;
}
.icon-btn:hover { background: var(--md-surface-container-highest); }
.icon-btn:focus-visible { outline: 3px solid var(--md-primary); outline-offset: 2px; }

/* ---------- Layout ---------- */
.shell { display: flex; min-height: calc(100vh - 58px); }
.nav {
  position: sticky; top: 58px; align-self: flex-start;
  width: 250px; flex: none; padding: 12px 8px;
  height: calc(100vh - 58px); overflow-y: auto;
  border-right: 1px solid var(--md-outline-variant);
  background: var(--md-surface-container-low);
}
.nav button {
  display: flex; align-items: center; gap: 12px; width: 100%;
  padding: 12px 16px; margin-bottom: 4px;
  border: none; border-radius: var(--radius-xl);
  background: transparent; color: var(--md-on-surface-variant);
  font: inherit; font-size: .9rem; text-align: left; cursor: pointer;
  transition: background .15s, color .15s;
}
.nav button .n { font-size: 1.1rem; width: 22px; text-align: center; }
.nav button:hover { background: var(--md-surface-container-high); }
.nav button.active {
  background: var(--md-secondary-container); color: var(--md-on-secondary-container);
  font-weight: 600;
}
.nav button:focus-visible { outline: 3px solid var(--md-primary); outline-offset: -2px; }

main { flex: 1; padding: 20px clamp(12px, 4vw, 40px) 80px; max-width: 1100px; margin: 0 auto; width: 100%; }

.module { display: none; animation: fade .25s ease; }
.module.active { display: block; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.module > h2 { font-size: 1.4rem; margin: 4px 0 2px; display: flex; align-items: center; gap: 10px; }
.module > h2 .chip { font-size: .68rem; padding: 3px 9px; border-radius: 999px; background: var(--md-tertiary-container); color: var(--md-on-tertiary-container); font-weight: 600; }
.module > .lead { color: var(--md-on-surface-variant); margin: 0 0 12px; font-size: .92rem; }

/* ---------- Explain-everything (Law 7) ---------- */
details.explain {
  background: var(--md-surface-container); border: 1px solid var(--md-outline-variant);
  border-radius: var(--radius-md); margin-bottom: 18px; overflow: hidden;
}
details.explain > summary {
  cursor: pointer; padding: 12px 16px; font-weight: 600; font-size: .86rem;
  color: var(--md-on-surface-variant); list-style: none; display: flex; align-items: center; gap: 8px;
}
details.explain > summary::-webkit-details-marker { display: none; }
details.explain > summary::before { content: "ⓘ"; color: var(--md-primary); }
details.explain[open] > summary { border-bottom: 1px solid var(--md-outline-variant); }
details.explain .body { padding: 12px 16px; font-size: .86rem; color: var(--md-on-surface); }
details.explain .body b { color: var(--md-primary); }
details.explain .body ol { margin: 6px 0 6px 18px; padding: 0; }
details.explain .status { margin-top: 8px; padding: 8px 10px; border-radius: var(--radius-sm); background: var(--md-surface-container-highest); font-size: .8rem; }

/* ---------- Cards ---------- */
.card {
  background: var(--md-surface-container-low); border: 1px solid var(--md-outline-variant);
  border-radius: var(--radius-lg); padding: 18px; margin-bottom: 16px; box-shadow: var(--shadow-1);
}
.card h3 { margin: 0 0 12px; font-size: 1.05rem; display: flex; align-items: center; gap: 8px; }
.grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.grid-2 { display: grid; gap: 16px; grid-template-columns: 1fr 1fr; }
@media (max-width: 720px) { .grid-2 { grid-template-columns: 1fr; } .nav { display: none; } }

/* ---------- Fields (Material 3 outlined) ---------- */
.field { display: flex; flex-direction: column; gap: 4px; margin-bottom: 4px; }
.field label { font-size: .78rem; color: var(--md-on-surface-variant); font-weight: 500; }
.field .hint { font-size: .7rem; color: var(--md-outline); }
.field input, .field select {
  font: inherit; font-size: .95rem; padding: 11px 12px;
  border: 1px solid var(--md-outline); border-radius: var(--radius-xs);
  background: var(--md-surface-container-lowest); color: var(--md-on-surface);
  width: 100%; transition: border-color .15s, box-shadow .15s;
}
.field input:focus, .field select:focus {
  outline: none; border-color: var(--md-primary); box-shadow: 0 0 0 2px var(--md-primary);
}
.field.ocr-filled input { border-color: var(--md-tertiary); background: var(--md-tertiary-container); }

/* slider rows */
.slider-row { display: flex; align-items: center; gap: 12px; }
.slider-row input[type=range] { flex: 1; accent-color: var(--md-primary); height: 4px; }
.slider-row .val { min-width: 74px; text-align: right; font-variant-numeric: tabular-nums; font-weight: 600; font-size: .9rem; }

/* ---------- Buttons ---------- */
.btn {
  font: inherit; font-weight: 600; font-size: .88rem; cursor: pointer;
  padding: 11px 20px; border-radius: 999px; border: none;
  background: var(--md-primary); color: var(--md-on-primary);
  display: inline-flex; align-items: center; gap: 8px; transition: filter .15s, box-shadow .15s;
}
.btn:hover { filter: brightness(1.06); box-shadow: var(--shadow-1); }
.btn:focus-visible { outline: 3px solid var(--md-primary); outline-offset: 2px; }
.btn.tonal { background: var(--md-secondary-container); color: var(--md-on-secondary-container); }
.btn.outline { background: transparent; color: var(--md-primary); border: 1px solid var(--md-outline); }
.btn.small { padding: 8px 14px; font-size: .8rem; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 4px; }

/* ---------- Metrics / KPI ---------- */
.kpis { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); }
.kpi {
  background: var(--md-surface-container); border-radius: var(--radius-md);
  padding: 14px; border: 1px solid var(--md-outline-variant);
}
.kpi .k-label { font-size: .74rem; color: var(--md-on-surface-variant); }
.kpi .k-val { font-size: 1.5rem; font-weight: 700; font-variant-numeric: tabular-nums; letter-spacing: -.5px; }
.kpi .k-val small { font-size: .8rem; font-weight: 500; color: var(--md-on-surface-variant); }
.kpi.good .k-val { color: var(--md-success); }
.kpi.warn { background: var(--md-warning-container); }
.kpi.bad { background: var(--md-error-container); color: var(--md-on-error-container); }

/* ---------- Banners ---------- */
.banner { padding: 12px 14px; border-radius: var(--radius-md); font-size: .86rem; margin: 10px 0; display: flex; gap: 10px; align-items: flex-start; }
.banner.info { background: var(--md-tertiary-container); color: var(--md-on-tertiary-container); }
.banner.warn { background: var(--md-warning-container); color: var(--md-on-surface); }
.banner.bad { background: var(--md-error-container); color: var(--md-on-error-container); }
.banner.good { background: var(--md-primary-container); color: var(--md-on-primary-container); }

/* ---------- Tables ---------- */
.table-wrap { overflow-x: auto; border-radius: var(--radius-md); border: 1px solid var(--md-outline-variant); }
table { width: 100%; border-collapse: collapse; font-size: .84rem; }
th, td { padding: 9px 12px; text-align: left; border-bottom: 1px solid var(--md-outline-variant); white-space: nowrap; }
th { background: var(--md-surface-container); font-weight: 600; position: sticky; top: 0; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
tr:last-child td { border-bottom: none; }
tr.total td { font-weight: 700; background: var(--md-surface-container-high); }
.rank-badge { display: inline-block; width: 22px; height: 22px; line-height: 22px; text-align: center; border-radius: 50%; background: var(--md-primary-container); color: var(--md-on-primary-container); font-size: .72rem; font-weight: 700; }

/* ---------- Dropzone ---------- */
.dropzone {
  border: 2px dashed var(--md-outline); border-radius: var(--radius-lg);
  padding: 32px 20px; text-align: center; cursor: pointer; transition: all .18s;
  background: var(--md-surface-container-lowest);
}
.dropzone:hover, .dropzone.drag { border-color: var(--md-primary); background: var(--md-primary-container); color: var(--md-on-primary-container); }
.dropzone .big { font-size: 2.4rem; }
.bill-preview { position: relative; margin-top: 14px; }
.bill-preview img { max-width: 100%; border-radius: var(--radius-md); border: 1px solid var(--md-outline-variant); }
.ocr-log { font-family: var(--mono); font-size: .76rem; white-space: pre-wrap; background: var(--md-surface-container); padding: 12px; border-radius: var(--radius-sm); max-height: 200px; overflow: auto; margin-top: 10px; }

/* ---------- Roof grid viz ---------- */
.roof-viz { width: 100%; overflow-x: auto; }
.roof-viz svg { display: block; margin: 0 auto; max-width: 100%; }
.panel-cell { fill: var(--md-primary); stroke: var(--md-surface); stroke-width: 1.5; }
.panel-cell.landscape { fill: var(--md-tertiary); }

/* charts */
.chart { width: 100%; overflow-x: auto; }
.chart svg { display: block; width: 100%; height: auto; }
.legend { display: flex; flex-wrap: wrap; gap: 12px; font-size: .78rem; margin-top: 6px; color: var(--md-on-surface-variant); }
.legend span { display: inline-flex; align-items: center; gap: 5px; }
.legend i { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }

/* string diagram */
.mppt-box { border: 1px solid var(--md-outline); border-radius: var(--radius-md); padding: 12px; background: var(--md-surface-container); }
.mppt-box.ok { border-color: var(--md-success); }
.mppt-box.bad { border-color: var(--md-error); }

/* toast */
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%) translateY(120px);
  background: var(--md-inverse-surface); color: var(--md-inverse-on-surface);
  padding: 12px 20px; border-radius: var(--radius-sm); box-shadow: var(--shadow-2);
  font-size: .86rem; z-index: 100; transition: transform .3s; max-width: 90vw;
}
.toast.show { transform: translateX(-50%) translateY(0); }

.muted { color: var(--md-on-surface-variant); }
.mono { font-family: var(--mono); }
.right { text-align: right; }
hr.sep { border: none; border-top: 1px solid var(--md-outline-variant); margin: 16px 0; }

/* skip link (accessibility / UIAx) */
.skip-link { position: absolute; left: -999px; top: 0; background: var(--md-primary); color: var(--md-on-primary); padding: 10px 16px; z-index: 100; border-radius: 0 0 8px 0; }
.skip-link:focus { left: 0; }

/* mobile bottom nav */
.mobile-nav { display: none; }
@media (max-width: 720px) {
  .mobile-nav {
    display: flex; position: fixed; bottom: 0; left: 0; right: 0; z-index: 45;
    background: var(--md-surface-container); border-top: 1px solid var(--md-outline-variant);
    overflow-x: auto; padding: 4px;
  }
  .mobile-nav button { flex: none; border: none; background: transparent; color: var(--md-on-surface-variant);
    font: inherit; font-size: .62rem; padding: 6px 10px; display: flex; flex-direction: column; align-items: center; gap: 2px; border-radius: 10px; cursor: pointer; }
  .mobile-nav button .n { font-size: 1.2rem; }
  .mobile-nav button.active { color: var(--md-primary); background: var(--md-secondary-container); }
  main { padding-bottom: 90px; }
}

/* ---------- Print / PDF report ---------- */
@media print {
  .app-bar, .nav, .mobile-nav, .no-print, details.explain summary::before, .btn-row { display: none !important; }
  .module { display: block !important; page-break-after: always; }
  body { background: #fff; color: #000; }
  .card, .kpi { border: 1px solid #ccc; box-shadow: none; }
  main { max-width: none; padding: 0; }
  :root { --md-surface: #fff; }
}