/* ===== EMC Tools — technical engineering aesthetic ===== */

:root {
  --bg: #0d0e10;
  --bg-card: #16181c;
  --bg-input: #0a0b0d;
  --border: #2a2d33;
  --border-strong: #3d4148;
  --text: #e8e6e0;
  --text-dim: #8a8f99;
  --text-faint: #555a63;
  --accent: #d4ff3f;       /* signal yellow-green */
  --accent-dim: #8a9e2a;
  --warn: #ff7849;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --serif: "Newsreader", Georgia, serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  min-height: 100vh;
  background-image:
    radial-gradient(circle at 20% 0%, rgba(212, 255, 63, 0.04), transparent 50%),
    radial-gradient(circle at 80% 100%, rgba(212, 255, 63, 0.03), transparent 50%);
}

/* ===== Masthead ===== */
.masthead {
  border-bottom: 1px solid var(--border);
  padding: 32px 0;
  background: rgba(13, 14, 16, 0.85);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}

.masthead-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 32px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 16px;
}

.brand-mark {
  font-size: 32px;
  color: var(--accent);
  line-height: 1;
}

.brand h1 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 22px;
  letter-spacing: -0.01em;
}

.sub {
  font-size: 11px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-top: 2px;
}

nav {
  display: flex;
  gap: 24px;
  font-size: 12px;
}

nav a {
  color: var(--text-dim);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding-bottom: 4px;
  border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}

nav a:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.group-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}

.group-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 18px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

.group-nav a.active,
.group-nav a:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(212, 255, 63, 0.1);
}

.sub-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.sub-nav button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-dim);
  font-size: 12px;
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

.sub-nav button.active,
.sub-nav button:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(212, 255, 63, 0.1);
}

.sub-nav.hidden {
  display: none !important;
}

.card.hidden {
  display: none;
}

@media (max-width: 920px) {
  .masthead-inner {
    flex-direction: column;
    align-items: stretch;
  }

  .group-nav,
  .sub-nav {
    justify-content: center;
    gap: 8px;
  }

  .group-nav a,
  .sub-nav button {
    flex: 1 1 auto;
    min-width: 120px;
    font-size: 11px;
    padding: 8px 14px;
  }

  .card-head {
    padding: 18px 20px 16px;
  }

  .card-body {
    gap: 0;
  }

  .inputs,
  .results {
    padding: 20px;
  }

  main {
    padding: 24px 16px;
  }
}

@media (max-width: 720px) {
  .group-nav a,
  .sub-nav button {
    flex: 1 1 100%;
    min-width: 0;
  }

  main {
    padding: 18px 12px;
  }
}

/* ===== Main ===== */
main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 32px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

/* ===== Card ===== */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}

.card::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 3px; height: 100%;
  background: var(--accent);
  opacity: 0.7;
}

.card-head {
  padding: 24px 32px 20px;
  border-bottom: 1px solid var(--border);
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 4px 16px;
  align-items: baseline;
}

.tag {
  font-size: 11px;
  color: var(--accent);
  letter-spacing: 0.1em;
  grid-row: span 2;
  align-self: start;
  border: 1px solid var(--accent-dim);
  padding: 2px 8px;
  border-radius: 2px;
}

.card-head h2 {
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.card-head p {
  font-size: 12px;
  color: var(--text-dim);
  grid-column: 2;
  margin-top: 4px;
}

/* ===== Body: inputs + results ===== */
.card-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}

@media (max-width: 920px) {
  .card-body { grid-template-columns: 1fr; }
}

.inputs {
  padding: 24px 32px;
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

@media (max-width: 920px) {
  .inputs { border-right: none; border-bottom: 1px solid var(--border); }
}

@media (max-width: 720px) {
  .inputs label {
    grid-template-columns: 1fr;
  }
  .inputs label em {
    grid-column: 1;
    grid-row: auto;
    margin: 0;
    position: static;
  }
}

.inputs label {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.inputs label span {
  color: var(--text-faint);
  font-style: italic;
  text-transform: none;
  letter-spacing: 0;
  margin-left: 4px;
}

.inputs label em {
  font-style: normal;
  color: var(--text-faint);
  font-size: 11px;
  min-width: 30px;
  text-align: left;
}

.inputs input {
  grid-column: 1 / -1;
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--mono);
  font-size: 14px;
  padding: 8px 12px;
  border-radius: 2px;
  outline: none;
  transition: border-color 0.15s;
}

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

.inputs label em {
  grid-column: 2;
  grid-row: 2;
  margin-top: -32px;
  margin-right: 12px;
  pointer-events: none;
  position: relative;
  z-index: 1;
}

button[type="submit"] {
  margin-top: 8px;
  background: var(--accent);
  color: #0a0b0d;
  border: none;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 12px 16px;
  border-radius: 2px;
  cursor: pointer;
  transition: background 0.15s, transform 0.05s;
}

button[type="submit"]:hover {
  background: #c4ef2f;
}

button[type="submit"]:active {
  transform: translateY(1px);
}

button[type="submit"]:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ===== Results ===== */
.results {
  padding: 24px 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 24px;
  transition: background 0.3s;
}

.results.flash {
  background: rgba(212, 255, 63, 0.04);
}

.r-main {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding-bottom: 16px;
  border-bottom: 1px dashed var(--border);
}

/* ===== Mobile card override ===== */
.card,
.card-body {
  max-height: none !important;
  height: auto !important;
  overflow: visible !important;
}

.card-head {
  position: static !important;
}

.r-main .label {
  font-size: 11px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.r-main .value {
  font-family: var(--serif);
  font-size: 42px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: -0.02em;
  line-height: 1;
}

.r-main .unit {
  font-size: 14px;
  color: var(--text-dim);
}

.r-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px 24px;
}

.r-grid > div {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.r-grid .label {
  font-size: 10px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.r-grid .value {
  font-size: 16px;
  color: var(--text);
  font-weight: 500;
}

.r-grid em {
  font-style: normal;
  font-size: 10px;
  color: var(--text-faint);
  margin-left: 4px;
}

/* ===== Footer ===== */
footer {
  border-top: 1px solid var(--border);
  padding: 32px;
  text-align: center;
  font-size: 11px;
  color: var(--text-faint);
  margin-top: 32px;
}

footer em {
  font-style: normal;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

footer .hint {
  margin-top: 8px;
  font-family: var(--serif);
  font-style: italic;
  font-size: 12px;
}