/* ── CSS Tokens ── */
:root {
  --bg:           #f7f1e3;
  --bg-alt:       #efe8d6;
  --surface:      #fdfaf3;
  --surface-2:    #f5edd8;
  --border:       #ddd0b3;
  --border-soft:  #e8dfc8;
  --text:         #2b1f0d;
  --text-muted:   #7a6545;
  --text-sub:     #a08860;
  --accent:       #b07d2e;
  --accent-h:     #c9913a;
  --accent-glow:  rgba(176,125,46,.16);
  --shadow:       rgba(100,70,20,.09);
  --mono-bg:      #f0e8d4;
}
[data-theme="dark"] {
  --bg:           #12100e;
  --bg-alt:       #1a1712;
  --surface:      #1f1c17;
  --surface-2:    #27231c;
  --border:       #38321f;
  --border-soft:  #302b1e;
  --text:         #ede0c4;
  --text-muted:   #9e8a68;
  --text-sub:     #6b5c40;
  --accent:       #c9913a;
  --accent-h:     #dcaa55;
  --accent-glow:  rgba(201,145,58,.20);
  --shadow:       rgba(0,0,0,.45);
  --mono-bg:      #1c1912;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  padding: 28px 16px 72px;
  transition: background .35s, color .35s;
  line-height: 1.65;
}

.container { max-width: 740px; margin: 0 auto; }

/* ── Header ── */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 36px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--border-soft);
}
.header h1 {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -.02em;
  color: var(--text);
}
.header p {
  font-size: .75rem;
  color: var(--text-muted);
  margin-top: 3px;
}
.pill {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  background: var(--accent-glow);
  border: 1px solid var(--border);
  color: var(--accent);
  font-size: .65rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 99px;
  letter-spacing: .05em;
  text-transform: uppercase;
}

/* ── Theme Toggle ── */
.theme-toggle { display: flex; align-items: center; gap: 9px; }
.toggle-label { font-size: .72rem; color: var(--text-muted); font-weight: 500; }
.toggle-btn {
  position: relative;
  width: 46px;
  height: 25px;
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: 99px;
  cursor: pointer;
  transition: background .3s, border-color .3s;
  flex-shrink: 0;
}
.toggle-btn::after {
  content: '';
  position: absolute;
  top: 3px; left: 3px;
  width: 17px; height: 17px;
  background: var(--accent);
  border-radius: 50%;
  transition: transform .3s cubic-bezier(.34,1.5,.64,1);
  box-shadow: 0 1px 4px var(--shadow);
}
[data-theme="dark"] .toggle-btn::after { transform: translateX(21px); }

/* ── Card ── */
.card {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: 16px;
  padding: 24px 26px 22px;
  margin-bottom: 14px;
  box-shadow: 0 2px 10px var(--shadow);
  transition: background .35s, border-color .35s;
}
.card-title {
  font-size: .68rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .09em;
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.card-title::before {
  content: '';
  display: block;
  width: 3px; height: 13px;
  background: var(--accent);
  border-radius: 2px;
}

/* ── Form ── */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 15px 18px;
}
.form-group { display: flex; flex-direction: column; gap: 5px; }
.form-group.full { grid-column: 1 / -1; }

label {
  font-size: .74rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: .01em;
}

input[type="number"],
input[type="text"],
select {
  width: 100%;
  padding: 9px 11px;
  background: var(--bg-alt);
  border: 1.5px solid var(--border-soft);
  border-radius: 9px;
  color: var(--text);
  font-family: 'Inter', sans-serif;
  font-size: .86rem;
  font-weight: 500;
  outline: none;
  transition: border-color .2s, box-shadow .2s, background .35s;
  -webkit-appearance: none;
  appearance: none;
}
select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='11' height='11' viewBox='0 0 12 12'%3E%3Cpath fill='%23a08860' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 11px center;
  padding-right: 30px;
}
input[type="number"]:focus,
input[type="text"]:focus,
select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
  background: var(--surface);
}

/* ── Hugging Face Input Group ── */
.hf-input-group {
  display: flex;
  gap: 10px;
  align-items: stretch;
}
.hf-input-group input[type="text"] {
  flex: 1;
}
.hf-input-group .btn-secondary {
  width: auto;
  flex-shrink: 0;
  padding: 9px 16px;
  font-size: .82rem;
}
.hf-status {
  margin-top: 6px;
  font-size: .74rem;
  min-height: 20px;
}
.hf-status.loading {
  color: var(--accent);
  font-style: italic;
}
.hf-status.success {
  color: #5fad76;
}
.hf-status.error {
  color: #d44e4e;
}

/* ── Slider ── */
.slider-hdr { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.slider-val {
  font-family: 'JetBrains Mono', monospace;
  font-size: .78rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-glow);
  padding: 2px 7px;
  border-radius: 6px;
}
input[type="range"] {
  width: 100%;
  height: 4px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--border);
  border-radius: 99px;
  outline: none;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
  cursor: pointer;
  transition: box-shadow .2s;
}
input[type="range"]::-webkit-slider-thumb:hover {
  box-shadow: 0 0 0 5px var(--accent-glow);
}

/* ── Buttons ── */
.btn-primary {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  font-family: 'Inter', sans-serif;
  font-size: .88rem;
  font-weight: 600;
  cursor: pointer;
  letter-spacing: .01em;
  transition: background .2s, transform .15s, box-shadow .2s;
  box-shadow: 0 3px 12px var(--accent-glow);
}
.btn-primary:hover { background: var(--accent-h); transform: translateY(-1px); }
.btn-primary:active { transform: translateY(0); }
.btn-secondary {
  width: 100%;
  padding: 11px;
  background: transparent;
  color: var(--accent);
  border: 1.5px solid var(--accent);
  border-radius: 10px;
  font-family: 'Inter', sans-serif;
  font-size: .86rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s, transform .15s;
}
.btn-secondary:hover { background: var(--accent-glow); transform: translateY(-1px); }
.btn-secondary:active { transform: translateY(0); }
.btn-row { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 11px; }

hr.soft { border: none; height: 1px; background: var(--border-soft); margin: 18px 0; }

/* ── Results ── */
.hidden { display: none; }

.result-hero { text-align: center; padding: 18px 0 14px; }
.result-hero .r-label {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--text-muted);
  margin-bottom: 6px;
}
.gpu-count {
  font-size: 4.2rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
  letter-spacing: -.04em;
}
.gpu-unit { font-size: 1rem; color: var(--text-muted); font-weight: 400; }

.result-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}
.stat-item {
  background: var(--surface-2);
  border-radius: 9px;
  padding: 11px 12px;
  border: 1px solid var(--border-soft);
}
.stat-label {
  font-size: .65rem;
  font-weight: 700;
  color: var(--text-sub);
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 4px;
}
.stat-val {
  font-family: 'JetBrains Mono', monospace;
  font-size: .84rem;
  font-weight: 500;
  color: var(--text);
}

/* ── LaTeX Steps ── */
.steps-title {
  font-size: .68rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .09em;
  margin: 18px 0 12px;
  display: flex;
  align-items: center;
  gap: 7px;
}
.steps-title::before {
  content: '';
  display: block;
  width: 3px; height: 12px;
  background: #5fad76;
  border-radius: 2px;
}
.latex-step {
  background: var(--mono-bg);
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  padding: 13px 15px;
  margin-bottom: 9px;
  transition: background .35s;
  overflow-x: auto;
}
.step-hdr {
  font-size: .67rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .07em;
  margin-bottom: 9px;
}
.katex-display { margin: 0 !important; }

/* ── Footer ── */
.footer {
  text-align: center;
  margin-top: 36px;
  font-size: .68rem;
  color: var(--text-sub);
}

/* ── Animation ── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}
.animate-in { animation: fadeUp .38s cubic-bezier(.23,1,.32,1) both; }

/* ── Responsive ── */
@media (max-width: 520px) {
  .form-grid { grid-template-columns: 1fr; }
  .result-stats { grid-template-columns: 1fr 1fr; }
  .btn-row { grid-template-columns: 1fr; }
  .header { flex-direction: column; align-items: flex-start; gap: 12px; }
}

@media print {
  body { background: #fff; color: #111; }
  .no-print { display: none !important; }
}