/* ============ DC Arc Lab — "Editorial Light" theme ============ */
@font-face { font-family: "Newsreader"; src: url("../fonts/newsreader-600.woff2") format("woff2"); font-weight: 600; font-style: normal; font-display: swap; }
@font-face { font-family: "Newsreader"; src: url("../fonts/newsreader-500.woff2") format("woff2"); font-weight: 500; font-style: normal; font-display: swap; }
@font-face { font-family: "Newsreader"; src: url("../fonts/newsreader-400i.woff2") format("woff2"); font-weight: 400; font-style: italic; font-display: swap; }

:root {
  --paper:     #f6f5f2;   /* page */
  --surface:   #ffffff;   /* cards */
  --surface-2: #faf9f6;   /* inset / subtle */
  --ink:       #1c1d20;   /* primary text */
  --ink-2:     #5f656d;   /* secondary */
  --ink-3:     #949aa2;   /* tertiary / captions */
  --ink-dim:   #5f656d;   /* (chart axis labels read this) */
  --line:      #e8e6e1;   /* hairline */
  --line-2:    #dcd9d3;   /* stronger hairline */
  --navy:      #1c3d5a;   /* structural accent / links */
  --navy-2:    #285a82;
  --navy-wash: #eef2f6;
  --ember:     #b23a2e;   /* hazard / incident energy */
  --ember-2:   #8f2c22;
  --ember-wash:#f6e9e6;
  --sage:      #4b7058;   /* safe */

  --accent-warn: var(--ember);
  --chart-grid: rgba(28, 29, 32, 0.07);
  --chart-axis: rgba(28, 29, 32, 0.30);
  --panel-solid: #ffffff;

  --serif: "Newsreader", "Iowan Old Style", "Source Serif 4", Charter, "Palatino Linotype", Georgia, serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", "Roboto Mono", Consolas, monospace;
  --maxw: 1140px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font-family: var(--sans); line-height: 1.6; font-size: 16px;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
h1, h2, h3, h4 { margin: 0; font-weight: 600; line-height: 1.15; }
a { color: inherit; text-decoration: none; }
.num { font-variant-numeric: tabular-nums; font-feature-settings: "tnum" 1; }

/* ---------- Header ---------- */
.site-head {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 18px;
  padding: 0 clamp(18px, 5vw, 44px); height: 60px;
  background: rgba(246, 245, 242, 0.82); backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--serif); font-weight: 600; font-size: 18px; letter-spacing: -0.01em; }
.brand-mark { width: 22px; height: 22px; }
.nav { display: flex; gap: 26px; margin-left: auto; font-size: 14.5px; }
.nav a { color: var(--ink-2); transition: color 0.15s; }
.nav a:hover { color: var(--ink); }
.lang-toggle { display: flex; gap: 2px; }
.lang-toggle button {
  background: transparent; border: 0; color: var(--ink-3);
  font: 600 13px/1 var(--sans); padding: 7px 9px; cursor: pointer; border-radius: 7px; transition: 0.15s;
}
.lang-toggle button.active { color: var(--ink); background: rgba(28, 29, 32, 0.06); }
.lang-toggle button:hover { color: var(--ink); }
.nav a:focus-visible, .chip:focus-visible, .btn:focus-visible, .btn-mini:focus-visible,
.lang-toggle button:focus-visible, .unit-toggle button:focus-visible,
.gallery figure:focus-visible, .doi-badge:focus-visible, summary:focus-visible {
  outline: 2px solid var(--navy); outline-offset: 2px; border-radius: 6px;
}
@media (max-width: 720px) { .nav { display: none; } }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
  font: 500 15px/1 var(--sans); padding: 13px 22px; border-radius: 999px;
  border: 1px solid transparent; transition: 0.18s; white-space: nowrap;
}
.btn-primary { background: var(--ink); color: #fff; }
.btn-primary:hover { background: #000; transform: translateY(-1px); }
.btn-ghost { border-color: var(--line-2); color: var(--ink); background: var(--surface); }
.btn-ghost:hover { border-color: var(--navy); color: var(--navy); }
.btn-mini { font-size: 13px; padding: 9px 15px; border: 1px solid var(--line-2); color: var(--ink-2); background: var(--surface); border-radius: 8px; cursor: pointer; }
.btn-mini:hover { border-color: var(--navy); color: var(--navy); }
.btn.done { background: var(--sage) !important; color: #fff !important; border-color: var(--sage); }
.link-arrow { color: var(--navy); font: 500 15px/1 var(--sans); display: inline-flex; align-items: center; gap: 6px; }
.link-arrow:hover { text-decoration: underline; text-underline-offset: 3px; }

/* ---------- Hero ---------- */
.hero { border-bottom: 1px solid var(--line); }
.hero-inner {
  max-width: var(--maxw); margin: 0 auto; padding: clamp(54px, 9vw, 104px) clamp(18px, 5vw, 44px);
  display: grid; grid-template-columns: 1.05fr 0.95fr; gap: clamp(28px, 5vw, 64px); align-items: center;
}
@media (max-width: 860px) { .hero-inner { grid-template-columns: 1fr; } }
.eyebrow { font: 600 12px/1.4 var(--sans); letter-spacing: 0.18em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 20px; }
.hero-title { font-family: var(--serif); font-weight: 600; font-size: clamp(2.5rem, 6vw, 4.1rem); letter-spacing: -0.02em; line-height: 1.04; color: var(--ink); margin-bottom: 22px; }
.hero-sub { max-width: 30ch; font-size: clamp(1.02rem, 1.6vw, 1.18rem); color: var(--ink-2); }
.hero-cta { display: flex; gap: 18px; align-items: center; margin: 30px 0 22px; flex-wrap: wrap; }
.hero-byline { font: 500 13.5px/1.4 var(--sans); color: var(--ink-3); }
.hero-byline em { font-style: italic; font-family: var(--serif); color: var(--ink-2); }
.hero-figure { margin: 0; }
.hero-figure .frame {
  border: 1px solid var(--line-2); border-radius: 14px; overflow: hidden; background: #0c1116;
  box-shadow: 0 24px 60px -28px rgba(20, 30, 45, 0.4), 0 4px 12px -6px rgba(20, 30, 45, 0.18);
}
.hero-figure video { width: 100%; display: block; aspect-ratio: 16 / 9; object-fit: cover; }
.hero-figure figcaption { font: 400 13px/1.5 var(--serif); font-style: italic; color: var(--ink-3); margin-top: 12px; padding-left: 2px; }

/* ---------- Sections ---------- */
.section { max-width: var(--maxw); margin: 0 auto; padding: clamp(56px, 9vw, 104px) clamp(18px, 5vw, 44px); }
.section.alt { max-width: none; background: var(--surface); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section.alt > * { max-width: var(--maxw); margin-left: auto; margin-right: auto; }
.section-head { margin-bottom: 38px; }
.section-head.sub { margin: 44px 0 20px; }
.kicker { font: 600 12px/1.4 var(--sans); letter-spacing: 0.16em; text-transform: uppercase; color: var(--ink-3); margin: 0 0 12px; }
.section-head h2 { font-family: var(--serif); font-weight: 600; font-size: clamp(1.9rem, 3.6vw, 2.7rem); letter-spacing: -0.015em; color: var(--ink); }
.lead { font-size: clamp(1.02rem, 1.5vw, 1.15rem); color: var(--ink-2); max-width: 62ch; }

/* ---------- Cards ---------- */
.panel { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; }

/* ---------- Calculator ---------- */
.calc-grid { display: grid; grid-template-columns: 360px 1fr; gap: 22px; align-items: start; }
@media (max-width: 880px) { .calc-grid { grid-template-columns: 1fr; } }

.inputs { padding: 24px; }
.presets { margin-bottom: 22px; padding-bottom: 20px; border-bottom: 1px solid var(--line); }
.presets-label { font: 600 11px/1 var(--sans); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 13px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { font: 500 13px/1 var(--sans); padding: 8px 13px; border-radius: 999px; cursor: pointer; background: var(--surface); border: 1px solid var(--line-2); color: var(--ink-2); transition: 0.15s; }
.chip:hover { border-color: var(--navy); color: var(--navy); }
.chip.active { background: var(--navy-wash); border-color: var(--navy); color: var(--navy); font-weight: 600; }
.hint { font-size: 13px; color: var(--ink-3); margin: 11px 0 0; line-height: 1.5; }

.field { margin-bottom: 17px; }
.field label { display: block; font: 600 11px/1 var(--sans); letter-spacing: 0.05em; text-transform: uppercase; color: var(--ink-2); margin-bottom: 8px; }
.control { display: flex; align-items: stretch; gap: 8px; }
.control input, .control select {
  flex: 1; min-width: 0; background: var(--surface); border: 1px solid var(--line-2); color: var(--ink);
  border-radius: 10px; padding: 12px 13px; font: 500 16px/1 var(--sans); font-variant-numeric: tabular-nums; transition: 0.15s; appearance: none;
}
.control input:focus, .control select:focus { outline: none; border-color: var(--navy); box-shadow: 0 0 0 3px rgba(28, 61, 90, 0.12); }
.control select { cursor: pointer; background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%235f656d' stroke-width='1.5' fill='none'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: right 13px center; padding-right: 32px; }
.suffix { display: flex; align-items: center; padding: 0 13px; font: 500 14px/1 var(--sans); color: var(--ink-3); background: var(--surface-2); border: 1px solid var(--line-2); border-radius: 10px; }
.unit-toggle { display: flex; border: 1px solid var(--line-2); border-radius: 10px; overflow: hidden; background: var(--surface); }
.unit-toggle button { background: transparent; border: 0; color: var(--ink-2); font: 600 13px/1 var(--sans); padding: 0 13px; cursor: pointer; transition: 0.15s; }
.unit-toggle button.active { background: var(--ink); color: #fff; }
.input-actions { margin-top: 20px; }

/* ---------- Results ---------- */
.results { padding: 26px 28px 24px; }
.results-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.results-head h3 { font: 600 12px/1 var(--sans); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); }
.badges { display: flex; gap: 7px; flex-wrap: wrap; }
.badge { font: 500 12px/1 var(--sans); padding: 6px 11px; border-radius: 999px; border: 1px solid; }
.badge-ok { color: var(--sage); border-color: #cfe0d4; background: #eef4f0; }
.badge-warn { color: var(--ember); border-color: #ecd2cd; background: var(--ember-wash); }
.preset-check { margin: 10px 0 0; min-height: 0; }
.repro { font: 500 13px/1.5 var(--sans); color: var(--ink-2); }
.repro.ok { color: var(--sage); }
.repro b { color: var(--ink); font-weight: 600; }

/* incident energy — the headline result */
.ie-block { display: grid; grid-template-columns: 1.2fr 1fr; gap: 22px; align-items: end; margin: 22px 0 4px; padding-bottom: 24px; border-bottom: 1px solid var(--line); }
@media (max-width: 540px) { .ie-block { grid-template-columns: 1fr; gap: 18px; } }
.ie-label { font: 600 11px/1 var(--sans); letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 8px; }
.ie-label em { text-transform: none; letter-spacing: 0; font-style: italic; font-family: var(--serif); color: var(--ink-3); }
.ie-value { font: 600 clamp(2.8rem, 7vw, 3.7rem)/0.95 var(--sans); font-variant-numeric: tabular-nums; letter-spacing: -0.03em; color: var(--ember); }
.ie-value small { font-size: 0.34em; font-weight: 500; color: var(--ink-3); letter-spacing: 0; margin-left: 6px; }
.ie-sub { font: 500 14px/1 var(--sans); font-variant-numeric: tabular-nums; color: var(--ink-3); margin-top: 8px; }
.ie-side { display: flex; flex-direction: column; gap: 12px; }
.ppe-badge { font: 600 13px/1.35 var(--sans); padding: 11px 14px; border-radius: 10px; border: 1px solid; text-align: center; }
.ppe-0 { color: var(--sage); border-color: #cfe0d4; background: #eef4f0; }
.ppe-1 { color: #7a6512; border-color: #e7dcc0; background: #f7f1e1; }
.ppe-2 { color: #9a6b1f; border-color: #e7d6bd; background: #f7eedd; }
.ppe-3 { color: var(--ember); border-color: #ecd2cd; background: var(--ember-wash); }
.ppe-4 { color: var(--ember-2); border-color: #e3c3bd; background: #f3e1dd; }
.ppe-5 { color: #fff; border-color: var(--ember-2); background: var(--ember-2); }
.afb { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.afb-label { display: flex; flex-direction: column; gap: 2px; font: 500 12.5px/1.3 var(--sans); color: var(--ink-2); }
.afb-sub { font-weight: 500; font-size: 11px; color: var(--ink-3); }
.afb-val { font: 600 15px/1.3 var(--sans); font-variant-numeric: tabular-nums; color: var(--ink); white-space: nowrap; }
.afb-val .dim { color: var(--ink-3); font-weight: 500; }

/* the four stats */
.stat-row { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 22px; }
@media (max-width: 540px) { .stat-row { grid-template-columns: repeat(2, 1fr); gap: 18px 0; } }
.stat { padding: 0 18px; border-left: 1px solid var(--line); }
.stat:first-child { padding-left: 0; border-left: 0; }
.stat-label { font: 600 11px/1 var(--sans); letter-spacing: 0.05em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 9px; }
.stat-val { font: 600 1.55rem/1 var(--sans); font-variant-numeric: tabular-nums; letter-spacing: -0.02em; color: var(--ink); }
.stat-val.accent { color: var(--navy); }

.warnings { display: flex; flex-direction: column; gap: 9px; margin-top: 20px; }
.warn { font: 500 13px/1.5 var(--sans); padding: 11px 13px; border-radius: 10px; border-left: 3px solid; }
.warn-range { color: #7a6512; background: #f9f4e6; border-color: #c9a83e; }
.warn-invalid { color: var(--ember-2); background: var(--ember-wash); border-color: var(--ember); }

.results.out-of-range .ie-block, .results.out-of-range .stat-row { opacity: 0.5; filter: grayscale(0.4); }

/* ---------- Validation (collapsible legacy comparison) ---------- */
.validation { max-width: var(--maxw); margin: 24px auto 0; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); overflow: hidden; }
.validation summary { cursor: pointer; padding: 20px 24px; display: flex; align-items: center; gap: 12px; list-style: none; }
.validation summary::-webkit-details-marker { display: none; }
.validation summary::before { content: "+"; font: 400 22px/1 var(--sans); color: var(--ink-3); width: 18px; text-align: center; transition: transform 0.2s; }
.validation[open] summary::before { content: "\2212"; }
.val-title .vt-main { display: block; font: 600 15px/1.3 var(--sans); color: var(--ink); }
.val-title .vt-sub { display: block; font: 400 13px/1.4 var(--sans); color: var(--ink-3); margin-top: 3px; }
.val-body { padding: 4px 24px 24px; }
.cmp-table { width: 100%; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.cmp-table th, .cmp-table td { text-align: right; padding: 13px 10px; font: 500 14px/1 var(--sans); }
.cmp-table th { font: 600 11px/1 var(--sans); letter-spacing: 0.05em; text-transform: uppercase; color: var(--ink-3); border-bottom: 1px solid var(--line-2); }
.cmp-table td:first-child, .cmp-table th:first-child { text-align: left; }
.cmp-table tbody tr { border-bottom: 1px solid var(--line); }
.cmp-table tbody tr:last-child { border-bottom: 0; }
.cmp-table tbody tr.hl td { background: var(--navy-wash); color: var(--ink); }
.cmp-table tbody tr.hl td:first-child { color: var(--navy); font-weight: 700; }
.cmp-table tbody tr.hl td:first-child::before { content: "\25C6  "; color: var(--navy); }
.cmp-table tbody td { color: var(--ink-2); }

/* ---------- Charts ---------- */
.chart-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.chart-card { padding: 22px; }
.chart-card.wide { grid-column: 1 / -1; }
.chart-card h4 { font: 600 1.02rem/1.2 var(--sans); margin-bottom: 5px; color: var(--ink); }
.canvas-wrap { position: relative; height: 280px; margin-top: 14px; }
.canvas-wrap canvas { width: 100%; height: 100%; display: block; }
@media (max-width: 760px) { .chart-grid { grid-template-columns: 1fr; } }

/* ---------- Model ---------- */
.model-grid { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 48px; align-items: start; }
@media (max-width: 820px) { .model-grid { grid-template-columns: 1fr; gap: 32px; } }
.model-text p { color: var(--ink-2); margin: 0 0 18px; max-width: 56ch; font-size: 1.02rem; }
.model-note { font-size: 14px; color: var(--ink-3) !important; border-left: 2px solid var(--line-2); padding-left: 14px; }
.eq-block { background: var(--surface-2); border: 1px solid var(--line); border-radius: 14px; padding: 22px 24px; margin: 22px 0; }
.eq-label { font: 600 11px/1 var(--sans); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 16px; }
.eq { font-family: var(--serif); font-style: italic; font-size: 1.2rem; line-height: 1.7; color: var(--ink); margin: 8px 0; }
.eq.dim { color: var(--ink-3); font-size: 1.02rem; margin-top: 14px; }
.eq sub, .eq sup { font-style: normal; }
.model-aside { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 26px; }
.circuit-label { font: 600 11px/1 var(--sans); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 14px; }
.circuit { width: 100%; height: auto; }
.circuit-eq { text-align: center; font-family: var(--serif); font-style: italic; font-size: 1.12rem; color: var(--ink); margin-top: 14px; padding-top: 18px; border-top: 1px solid var(--line); }
.circuit-eq sub { font-style: normal; }

/* ---------- Simulation ---------- */
.sim-grid { display: grid; grid-template-columns: 1.4fr 1fr; gap: 36px; align-items: center; }
@media (max-width: 820px) { .sim-grid { grid-template-columns: 1fr; } }
.sim-video { padding: 0; overflow: hidden; }
.sim-video video { width: 100%; display: block; background: #0c1116; }
.sim-video .cap { font: 400 13px/1.5 var(--serif); font-style: italic; color: var(--ink-3); margin: 14px 18px 16px; }
.sim-text p { color: var(--ink-2); font-size: 1.05rem; }
.gallery { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 34px; }
@media (max-width: 760px) { .gallery { grid-template-columns: repeat(2, 1fr); } }
.gallery figure { margin: 0; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; background: var(--surface); cursor: zoom-in; transition: box-shadow 0.2s, transform 0.2s; }
.gallery figure:hover { box-shadow: 0 12px 30px -16px rgba(20, 30, 45, 0.35); transform: translateY(-2px); }
.gallery img { width: 100%; aspect-ratio: 16 / 10; object-fit: cover; display: block; background: #0c1116; }
.gallery figcaption { font: 500 12px/1.4 var(--sans); color: var(--ink-2); padding: 11px 13px; }

/* ---------- Paper ---------- */
.paper-card { padding: clamp(32px, 5vw, 56px); }
.paper-quote { font-family: var(--serif); font-style: italic; font-weight: 400; font-size: clamp(1.3rem, 2.8vw, 1.9rem); line-height: 1.4; color: var(--ink); max-width: 30ch; margin: 0 0 30px; }
.paper-meta { display: flex; flex-wrap: wrap; gap: 6px 28px; align-items: baseline; padding-top: 26px; border-top: 1px solid var(--line); }
.paper-title { font-family: var(--serif); font-weight: 600; font-size: 1.3rem; color: var(--ink); flex: 1 1 280px; min-width: 240px; }
.paper-authors { color: var(--ink-2); font: 500 15px/1.5 var(--sans); }
.paper-venue { color: var(--ink-3); font-size: 14px; margin: 4px 0 0; }
.doi-badge { display: inline-flex; align-items: stretch; margin: 22px 0; border: 1px solid var(--line-2); border-radius: 8px; overflow: hidden; font: 500 13px/1 var(--mono); }
.doi-badge span { display: flex; align-items: center; background: var(--ink); color: #fff; padding: 0 12px; font-family: var(--sans); font-weight: 600; letter-spacing: 0.04em; }
.doi-badge code { padding: 10px 13px; color: var(--ink-2); transition: color 0.15s; }
.doi-badge:hover code { color: var(--navy); }
.paper-actions { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 6px; }

/* ---------- Footer ---------- */
.site-foot { max-width: var(--maxw); margin: 0 auto; padding: 48px clamp(18px, 5vw, 44px) 64px; border-top: 1px solid var(--line); }
.disclaimer { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 20px 22px; }
.disclaimer h4 { font: 600 11px/1 var(--sans); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ember); margin-bottom: 11px; }
.disclaimer p { font-size: 13.5px; color: var(--ink-2); margin: 0; max-width: 92ch; line-height: 1.6; }
.foot-note { text-align: center; font: 400 13px/1.5 var(--serif); font-style: italic; color: var(--ink-3); margin-top: 28px; }

/* ---------- Lightbox ---------- */
.lightbox { border: 1px solid var(--line-2); background: var(--surface); border-radius: 14px; padding: 14px; max-width: 92vw; max-height: 92vh; cursor: zoom-out; box-shadow: 0 40px 80px -30px rgba(20, 30, 45, 0.5); }
.lightbox::backdrop { background: rgba(28, 29, 32, 0.55); backdrop-filter: blur(2px); }
.lightbox img { max-width: 86vw; max-height: 78vh; border-radius: 8px; display: block; background: #0c1116; }
.lightbox .lb-cap { font: 400 13.5px/1.5 var(--serif); font-style: italic; color: var(--ink-2); margin: 12px 4px 2px; text-align: center; }

/* ---------- Responsive ---------- */
@media (max-width: 880px) { .cmp-table { font-size: 13px; } .cmp-table th, .cmp-table td { padding: 11px 7px; } }
@media (max-width: 420px) {
  .ie-value { font-size: 2.7rem; }
  .stat-val { font-size: 1.3rem; }
  .cmp-table { font-size: 11.5px; } .cmp-table th, .cmp-table td { padding: 9px 4px; }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; scroll-behavior: auto; transition: none !important; } }