/* ============================================================
   THE QUANTIFIER — 3lite Education
   Design System v1.0 | "Lab Terminal" Aesthetic
   Mirrors TheEqualizer 3lite-style.css v4.0 exactly,
   extended with Quantifier-specific components.
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Space+Mono:ital,wght@0,400;0,700;1,400&family=DM+Sans:opsz,wght@9..40,300;9..40,400;9..40,500;9..40,600;9..40,700;9..40,800&display=swap');

/* 1. ROOT VARIABLES */
:root {
  --bg:             #080a0f;
  --bg-raised:      #0d1017;
  --bg-surface:     #121620;
  --bg-elevated:    #171d2a;
  --bg-hover:       #1e2535;
  --border:         rgba(255,255,255,0.07);
  --border-mid:     rgba(255,255,255,0.12);
  --border-strong:  rgba(255,255,255,0.22);
  --text-primary:   #e8edf5;
  --text-secondary: #6b7a99;
  --text-muted:     #3d4a63;
  --cyan:    #00e5cc;
  --blue:    #3b82f6;
  --green:   #22d3a1;
  --orange:  #f59e0b;
  --red:     #ef4444;
  --purple:  #a855f7;
  --glow-cyan:  0 0 20px rgba(0,229,204,0.3), 0 0 60px rgba(0,229,204,0.1);
  --glass:         rgba(13,16,23,0.88);
  --glass-border:  rgba(255,255,255,0.08);
  --grad-brand:    linear-gradient(135deg, #00e5cc, #3b82f6);
  --font-ui:   'DM Sans', sans-serif;
  --font-mono: 'Space Mono', monospace;
  --r-sm: 8px; --r-md: 14px; --r-lg: 20px; --r-xl: 28px; --r-2xl: 36px;
  --ease-spring: cubic-bezier(0.175, 0.885, 0.32, 1.275);
  --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
}

body.light-mode {
  --bg:             #f0f2f7;
  --bg-raised:      #f7f8fc;
  --bg-surface:     #ffffff;
  --bg-elevated:    #ffffff;
  --bg-hover:       #eef0f7;
  --border:         rgba(0,0,0,0.07);
  --border-mid:     rgba(0,0,0,0.11);
  --border-strong:  rgba(0,0,0,0.2);
  --text-primary:   #111827;
  --text-secondary: #6b7280;
  --text-muted:     #9ca3af;
  --cyan:    #009e8e;
  --blue:    #2563eb;
  --green:   #059669;
  --orange:  #d97706;
  --red:     #dc2626;
  --purple:  #7c3aed;
  --glow-cyan:   none;
  --glass:         rgba(255,255,255,0.92);
  --glass-border:  rgba(0,0,0,0.07);
  --grad-brand:    linear-gradient(135deg, #009e8e, #2563eb);
}

/* 2. RESET & BASE */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-ui);
  font-size: 15px;
  line-height: 1.5;
  color: var(--text-primary);
  background: var(--bg);
  overflow-x: hidden;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -webkit-user-select: none;
  user-select: none;
  transition: background 0.4s var(--ease-smooth), color 0.4s var(--ease-smooth);
}
input, textarea, select { -webkit-user-select: text; user-select: text; }
img, svg { display: block; }
button { font-family: var(--font-ui); cursor: pointer; border: none; background: none; }

/* 3. BACKGROUND */
.fluid-bg {
  position: fixed; inset: 0; z-index: 0;
  pointer-events: none; overflow: hidden;
}
.fluid-bg::before {
  content: ''; position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(0,229,204,0.028) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,229,204,0.028) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 90% 80% at 50% 0%, black 20%, transparent 100%);
  animation: grid-drift 40s linear infinite;
}
.fluid-bg::after {
  content: ''; position: absolute; inset: 0;
  background:
    radial-gradient(ellipse 70% 50% at 10% 5%, rgba(0,229,204,0.055) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 90% 90%, rgba(59,130,246,0.05) 0%, transparent 60%);
}
body.light-mode .fluid-bg::before {
  background-image:
    linear-gradient(rgba(0,0,0,0.028) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,0,0.028) 1px, transparent 1px);
  opacity: 0.5;
}
body.light-mode .fluid-bg::after {
  background:
    radial-gradient(ellipse 70% 50% at 10% 5%, rgba(0,158,142,0.04) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 90% 90%, rgba(37,99,235,0.04) 0%, transparent 60%);
}
@keyframes grid-drift {
  0% { transform: translateY(0); }
  100% { transform: translateY(48px); }
}

/* 4. LAYOUT */
.app-container {
  position: relative; z-index: 1;
  width: 100%; max-width: 680px;
  margin: 0 auto;
  padding: 0 16px 48px;
}

/* 5. HEADER */
.app-header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 20px 0 0; margin-bottom: 24px;
}
.brand-block { display: flex; flex-direction: column; gap: 2px; }
.brand-name {
  font-family: var(--font-mono); font-size: 13px; font-weight: 700;
  letter-spacing: 0.15em; text-transform: uppercase;
  color: var(--cyan); text-shadow: var(--glow-cyan);
}
.brand-sub {
  font-size: 11px; font-weight: 500; letter-spacing: 0.06em;
  color: var(--text-muted); text-transform: uppercase;
}
.header-controls { display: flex; align-items: center; gap: 10px; }
.theme-icon { font-size: 16px; line-height: 1; user-select: none; -webkit-user-select: none; }

/* Theme toggle */
.theme-toggle { position: relative; width: 44px; height: 24px; flex-shrink: 0; }
.theme-toggle input { opacity: 0; width: 0; height: 0; position: absolute; }
.toggle-track {
  position: absolute; inset: 0;
  background: var(--bg-elevated); border: 1px solid var(--border-mid);
  border-radius: 100px; cursor: pointer;
  transition: all 0.3s var(--ease-smooth);
}
.toggle-track::before {
  content: ''; position: absolute; top: 3px; left: 3px;
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--text-muted);
  transition: all 0.3s var(--ease-spring);
}
.theme-toggle input:checked + .toggle-track { background: rgba(0,229,204,0.15); border-color: rgba(0,229,204,0.4); }
.theme-toggle input:checked + .toggle-track::before { transform: translateX(20px); background: var(--cyan); box-shadow: 0 0 8px rgba(0,229,204,0.6); }

/* 6. PANELS */
.panel {
  background: var(--bg-surface); border: 1px solid var(--border);
  border-radius: var(--r-xl); padding: 24px; margin-top: 16px;
  position: relative; overflow: hidden;
  transition: border-color 0.3s var(--ease-smooth), background 0.4s var(--ease-smooth);
}
.panel::before {
  content: ''; position: absolute; top: 0; left: 20%; right: 20%; height: 1px;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.07), transparent);
}
.panel:hover { border-color: var(--border-mid); }

/* 7. TYPOGRAPHY */
.section-eyebrow {
  font-family: var(--font-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--cyan); margin-bottom: 6px; text-shadow: var(--glow-cyan);
}
.section-title { font-size: 26px; font-weight: 800; letter-spacing: -0.5px; color: var(--text-primary); line-height: 1.2; }
.section-desc  { font-size: 13px; color: var(--text-secondary); line-height: 1.6; margin-top: 4px; }
.mono { font-family: var(--font-mono); }

.app-icon {
  width: 72px; height: 72px; border-radius: 20px;
  background: linear-gradient(145deg, #141c2e, #0d1117);
  border: 1px solid rgba(0,229,204,0.18);
  box-shadow: 0 0 0 1px rgba(0,229,204,0.07), 0 16px 40px rgba(0,0,0,0.5), inset 0 1px 0 rgba(255,255,255,0.05);
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 16px; position: relative; overflow: hidden;
}
.app-icon::after {
  content: ''; position: absolute; top: -30%; left: -10%; width: 120%; height: 60%;
  background: linear-gradient(to bottom, rgba(0,229,204,0.07), transparent);
  transform: rotate(-8deg);
}
.app-icon svg { z-index: 1; filter: drop-shadow(0 0 8px rgba(0,229,204,0.55)); }
body.light-mode .app-icon {
  background: linear-gradient(145deg, #dde3f0, #edf0f8);
  border-color: rgba(0,158,142,0.2);
  box-shadow: 0 8px 24px rgba(0,0,0,0.08), inset 0 1px 0 rgba(255,255,255,0.9);
}

/* 8. INPUTS */
.input-field {
  width: 100%; height: 50px; padding: 0 16px;
  background: var(--bg-raised); border: 1px solid var(--border-mid);
  border-radius: var(--r-md);
  font-family: var(--font-mono); font-size: 14px; color: var(--text-primary);
  outline: none; transition: all 0.2s var(--ease-smooth);
  -webkit-appearance: none; appearance: none;
}
.input-field::placeholder { color: var(--text-muted); font-family: var(--font-ui); font-size: 13px; }
.input-field:focus {
  border-color: var(--cyan);
  background: var(--bg-surface);
  box-shadow: 0 0 0 3px rgba(0,229,204,0.1), var(--glow-cyan);
}
.input-field.error { border-color: var(--red); animation: shake 0.4s var(--ease-smooth); }
select.input-field {
  cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' fill='none'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236b7a99' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 14px center; padding-right: 36px;
}
body.light-mode select.input-field { background-color: var(--bg-raised); color: var(--text-primary); }
.input-label {
  font-family: var(--font-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--text-muted); margin-bottom: 6px; display: block;
}
.input-row { display: flex; gap: 10px; align-items: center; margin-bottom: 14px; }

/* 9. BUTTONS */
.btn {
  display: flex; align-items: center; justify-content: center; gap: 8px;
  width: 100%; height: 50px; padding: 0 20px;
  border-radius: var(--r-md);
  font-family: var(--font-ui); font-size: 15px; font-weight: 700;
  cursor: pointer; border: none; outline: none;
  transition: all 0.2s var(--ease-spring);
  position: relative; overflow: hidden;
}
.btn::after { content: ''; position: absolute; inset: 0; background: rgba(255,255,255,0); transition: background 0.15s; }
.btn:hover::after { background: rgba(255,255,255,0.06); }
.btn:active { transform: scale(0.97); }
.btn-cyan { background: var(--grad-brand); color: #030608; box-shadow: 0 4px 20px rgba(0,229,204,0.22); }
.btn-cyan:hover { box-shadow: 0 6px 28px rgba(0,229,204,0.38); }
.btn-blue { background: var(--blue); color: #fff; box-shadow: 0 4px 20px rgba(59,130,246,0.22); }
.btn-blue:hover { box-shadow: 0 6px 28px rgba(59,130,246,0.38); }
.btn-ghost { background: transparent; border: 1px solid var(--border-mid); color: var(--text-secondary); }
.btn-ghost:hover { border-color: var(--border-strong); color: var(--text-primary); }
.btn-sm { height: 40px; font-size: 13px; padding: 0 16px; }
body.light-mode .btn-cyan { color: #fff; }

/* 10. SEGMENTED CONTROL */
.seg-control {
  display: flex; background: var(--bg-raised);
  border: 1px solid var(--border); border-radius: var(--r-md);
  padding: 4px; margin-bottom: 20px; gap: 2px;
}
.seg-btn {
  flex: 1; text-align: center; padding: 9px 8px;
  font-size: 13px; font-weight: 600; color: var(--text-secondary);
  border-radius: var(--r-sm); cursor: pointer;
  transition: all 0.2s var(--ease-smooth); white-space: nowrap;
}
.seg-btn:hover:not(.active) { color: var(--text-primary); background: var(--bg-hover); }
.seg-btn.active { background: var(--bg-elevated); color: var(--cyan); box-shadow: 0 1px 6px rgba(0,0,0,0.25), 0 0 0 1px var(--border-mid); }

/* 11. CHEM KEYBOARD */
.chem-keyboard {
  display: flex; gap: 6px; overflow-x: auto;
  padding: 0 0 14px; margin-bottom: 14px;
  border-bottom: 1px solid var(--border); scrollbar-width: none;
}
.chem-keyboard::-webkit-scrollbar { display: none; }
.chem-key {
  flex: 0 0 auto; padding: 7px 14px;
  background: var(--bg-elevated); border: 1px solid var(--border-mid);
  border-radius: var(--r-sm);
  font-family: var(--font-mono); font-size: 13px; font-weight: 700; color: var(--cyan);
  cursor: pointer; user-select: none;
  transition: all 0.12s var(--ease-smooth); white-space: nowrap;
}
.chem-key:hover { background: var(--bg-hover); border-color: var(--cyan); }
.chem-key:active { background: rgba(0,229,204,0.1); transform: scale(0.94); box-shadow: var(--glow-cyan); }

/* 12. STEP CARDS */
.step-card {
  background: var(--bg-raised); border: 1px solid var(--border);
  border-radius: var(--r-lg); padding: 18px 20px; margin-bottom: 12px;
  text-align: left; position: relative; overflow: hidden;
  transition: border-color 0.2s;
  animation: fade-up 0.4s var(--ease-smooth) both;
}
.step-card:hover { border-color: var(--border-mid); }
.step-label {
  font-family: var(--font-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--cyan); margin-bottom: 10px; display: block;
}
.math-text {
  font-family: var(--font-mono); font-size: 13px; line-height: 1.8;
  color: var(--text-primary); white-space: pre-line;
}

/* 13. TOAST */
#toast-container {
  position: fixed; top: -80px; left: 50%; transform: translateX(-50%);
  z-index: 9999; display: flex; align-items: center; gap: 8px;
  padding: 12px 20px;
  background: var(--bg-elevated); border: 1px solid var(--border-mid);
  border-radius: 100px;
  font-size: 14px; font-weight: 600; color: var(--text-primary);
  white-space: nowrap; box-shadow: 0 8px 32px rgba(0,0,0,0.4);
  transition: top 0.45s var(--ease-spring);
}
#toast-container.show { top: 20px; }
#toast-container.toast-error   { border-color: rgba(239,68,68,0.4);   color: var(--red);   }
#toast-container.toast-success { border-color: rgba(34,211,161,0.4);  color: var(--green); }
#toast-container.toast-info    { border-color: rgba(0,229,204,0.3);   color: var(--cyan);  }

/* 14. ANIMATIONS */
@keyframes fade-up  { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: translateY(0); } }
@keyframes shake    { 0%,100%{transform:translateX(0)} 20%{transform:translateX(-6px)} 40%{transform:translateX(6px)} 60%{transform:translateX(-4px)} 80%{transform:translateX(4px)} }
@keyframes spin     { to { transform: rotate(360deg); } }
@keyframes pulse-in { 0%{transform:scale(0.92);opacity:0} 100%{transform:scale(1);opacity:1} }

/* 15. QUANTIFIER COMPONENTS */

/* Equation preview bar */
.eq-preview {
  font-family: var(--font-mono); font-size: 16px;
  color: var(--cyan); text-align: center;
  padding: 14px 16px;
  background: var(--bg-raised); border: 1px solid var(--border-mid);
  border-radius: var(--r-md); margin-bottom: 16px;
  min-height: 50px; display: flex; align-items: center; justify-content: center;
  gap: 6px; flex-wrap: wrap; letter-spacing: 0.04em;
  transition: border-color 0.2s;
}
.eq-preview.empty   { color: var(--text-muted); font-family: var(--font-ui); font-size: 13px; }
.eq-preview.valid   { border-color: rgba(0,229,204,0.3); }
.eq-preview.invalid { border-color: rgba(239,68,68,0.3); color: var(--red); }

/* AI balance output */
.ai-balance-card {
  background: rgba(0,229,204,0.04); border: 1px solid rgba(0,229,204,0.18);
  border-radius: var(--r-lg); padding: 18px 20px; margin-top: 16px;
  animation: fade-up 0.4s var(--ease-spring) both;
}
.ai-badge {
  display: inline-flex; align-items: center; gap: 5px;
  font-family: var(--font-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--purple); padding: 3px 9px; border-radius: 100px;
  background: rgba(168,85,247,0.1); border: 1px solid rgba(168,85,247,0.25);
  margin-bottom: 10px;
}
.ai-balanced-eq {
  font-family: var(--font-mono); font-size: 17px; font-weight: 700;
  color: var(--text-primary); margin-bottom: 12px;
  padding: 10px 14px; background: var(--bg-raised);
  border-radius: var(--r-sm); border: 1px solid var(--border-mid);
}
.ai-steps { list-style: none; }
.ai-steps li {
  font-size: 13px; color: var(--text-secondary); line-height: 1.6;
  padding: 5px 0 5px 16px; border-left: 2px solid var(--border-mid);
  margin-bottom: 6px; position: relative;
}
.ai-steps li::before {
  content: '→'; position: absolute; left: -1px;
  font-family: var(--font-mono); font-size: 11px; color: var(--cyan);
  transform: translateX(-50%) translateY(-1px);
}

/* Molar mass table */
.mw-table { width: 100%; border-collapse: collapse; font-family: var(--font-mono); font-size: 12px; }
.mw-table td { padding: 6px 8px; border-bottom: 1px solid var(--border); color: var(--text-secondary); }
.mw-table td:first-child { color: var(--text-primary); font-weight: 700; }
.mw-table td:last-child  { text-align: right; color: var(--cyan); }
.mw-table tr:last-child td { border-bottom: none; }

/* Species grid */
.species-grid {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 10px; margin-top: 16px;
}
.species-card {
  background: var(--bg-raised); border: 1px solid var(--border);
  border-radius: var(--r-lg); padding: 14px 16px;
  position: relative; transition: border-color 0.2s;
  animation: fade-up 0.35s var(--ease-smooth) both;
}
.species-card:hover { border-color: var(--border-mid); }
.species-card.reactant { border-left: 3px solid var(--blue); }
.species-card.product  { border-left: 3px solid var(--green); }
.species-card.limiting {
  border-color: var(--orange); border-left: 3px solid var(--orange);
  box-shadow: 0 0 0 1px rgba(245,158,11,0.15), 0 0 20px rgba(245,158,11,0.08);
}
.species-name { font-family: var(--font-mono); font-size: 15px; font-weight: 700; color: var(--text-primary); margin-bottom: 2px; }
.species-meta { font-size: 11px; color: var(--text-muted); margin-bottom: 10px; }

/* Badges */
.species-badge {
  display: inline-flex; align-items: center; gap: 4px;
  font-family: var(--font-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  padding: 3px 8px; border-radius: 100px;
  position: absolute; top: 12px; right: 12px;
}
.badge-reactant { background: rgba(59,130,246,0.1);  color: var(--blue);   border: 1px solid rgba(59,130,246,0.2); }
.badge-product  { background: rgba(34,211,161,0.1);  color: var(--green);  border: 1px solid rgba(34,211,161,0.2); }
.badge-limiting { background: rgba(245,158,11,0.15); color: var(--orange); border: 1px solid rgba(245,158,11,0.3); }

/* Value rows inside species cards */
.value-row    { display: flex; align-items: baseline; gap: 6px; margin-bottom: 3px; }
.value-num    { font-family: var(--font-mono); font-size: 15px; font-weight: 700; color: var(--text-primary); }
.value-unit   { font-size: 11px; color: var(--text-muted); }
.value-label  { font-size: 11px; color: var(--text-secondary); margin-bottom: 6px; }

/* Excess info inside species card */
.excess-tag {
  margin-top: 8px; padding: 5px 8px;
  background: rgba(59,130,246,0.07); border: 1px solid rgba(59,130,246,0.15);
  border-radius: var(--r-sm); font-size: 11px; color: var(--blue);
  font-family: var(--font-mono);
}

/* Summary chips */
.results-bar { display: flex; gap: 10px; margin-top: 16px; flex-wrap: wrap; }
.result-chip { flex: 1; min-width: 80px; background: var(--bg-raised); border: 1px solid var(--border); border-radius: var(--r-lg); padding: 14px 16px; text-align: center; }
.result-chip.highlight { border-color: rgba(0,229,204,0.3); background: rgba(0,229,204,0.04); }
.result-chip-val   { font-family: var(--font-mono); font-size: 18px; font-weight: 700; color: var(--cyan); line-height: 1; }
.result-chip-label { font-size: 11px; color: var(--text-muted); margin-top: 4px; }

/* Limiting reagent banner */
.limiting-banner {
  display: flex; align-items: center; gap: 10px;
  padding: 12px 16px;
  background: rgba(245,158,11,0.07); border: 1px solid rgba(245,158,11,0.2);
  border-radius: var(--r-md); margin-top: 16px;
  font-size: 13px; font-weight: 600; color: var(--orange);
  animation: fade-up 0.3s var(--ease-spring);
}
.limiting-banner .icon { font-size: 18px; flex-shrink: 0; }

/* % Yield */
.yield-input-row { display: flex; gap: 10px; align-items: flex-end; flex-wrap: wrap; }
.yield-input-wrap { flex: 1; min-width: 120px; }
.yield-bar-bg {
  height: 8px; background: var(--bg-raised); border-radius: 100px;
  margin-top: 12px; overflow: hidden; border: 1px solid var(--border);
}
.yield-bar-fill {
  height: 100%; background: var(--grad-brand);
  border-radius: 100px; transition: width 0.6s var(--ease-spring); width: 0%;
}
.info-row {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 12px; color: var(--text-muted); margin-top: 4px;
}
.info-row b { color: var(--text-secondary); }

/* Loading spinner */
.loading-spin {
  width: 16px; height: 16px;
  border: 2px solid rgba(0,229,204,0.25);
  border-top-color: var(--cyan);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  flex-shrink: 0;
}

/* Utility */
sub { font-size: 0.65em; vertical-align: sub; }
.mt-2{margin-top:8px} .mt-3{margin-top:12px} .mt-4{margin-top:16px} .mt-5{margin-top:20px}
.text-cyan   { color: var(--cyan); }
.text-blue   { color: var(--blue); }
.text-orange { color: var(--orange); }
.text-green  { color: var(--green); }
.text-red    { color: var(--red); }
.text-muted  { color: var(--text-muted); }

/* 16. LIGHT MODE TWEAKS */
body.light-mode .section-eyebrow, body.light-mode .brand-name { text-shadow: none; }
body.light-mode .chem-key:active { box-shadow: none; }
body.light-mode .result-chip.highlight { background: rgba(0,158,142,0.06); }
body.light-mode .ai-balance-card { background: rgba(0,158,142,0.04); border-color: rgba(0,158,142,0.2); }

/* Pending theme (avoids FOUC) */
html.light-mode-pending body {
  --bg: #f0f2f7; --bg-raised: #f7f8fc; --bg-surface: #ffffff; --bg-elevated: #ffffff;
  --border: rgba(0,0,0,0.07); --border-mid: rgba(0,0,0,0.11);
  --text-primary: #111827; --text-secondary: #6b7280; --text-muted: #9ca3af;
  --cyan: #009e8e; --blue: #2563eb; --green: #059669; --orange: #d97706;
  --red: #dc2626; --purple: #7c3aed;
  --glow-cyan: none; --glass: rgba(255,255,255,0.92);
  --grad-brand: linear-gradient(135deg, #009e8e, #2563eb);
  background: #f0f2f7; color: #111827;
}

/* 17. RESPONSIVE */
@media (max-width: 480px) {
  .app-container { padding: 0 12px 36px; }
  .panel { padding: 18px 16px; border-radius: var(--r-lg); }
  .section-title { font-size: 22px; }
  .species-grid { grid-template-columns: 1fr; }
  .results-bar { flex-direction: column; }
  .yield-input-row { flex-direction: column; }
}

@media (min-width: 900px) {
  .app-container { max-width: 860px; padding: 0 32px 56px; }
  body { font-size: 16px; }
  .app-header { padding-top: 32px; margin-bottom: 32px; }
  .brand-name { font-size: 15px; letter-spacing: 0.18em; }
  .brand-sub  { font-size: 12px; }
  .panel { padding: 36px 40px; border-radius: var(--r-2xl); }
  .section-eyebrow { font-size: 11px; margin-bottom: 8px; }
  .section-title   { font-size: 34px; letter-spacing: -1px; }
  .section-desc    { font-size: 15px; }
  .seg-btn         { font-size: 14px; padding: 11px 16px; }
  .input-field     { height: 54px; font-size: 15px; }
  .btn             { height: 54px; font-size: 16px; }
  .chem-key        { padding: 8px 16px; font-size: 14px; }
  .app-icon        { width: 80px; height: 80px; border-radius: 22px; margin-bottom: 20px; }
  .species-name    { font-size: 16px; }
  .result-chip-val { font-size: 20px; }
}

@media (min-width: 1200px) {
  .app-container { max-width: 960px; }
  .section-title { font-size: 38px; }
}