:root{--bg:#0a0a0f;--bg-card:rgba(18,18,30,0.85);--bg-surface:#12121e;--text:#e8e8f0;--text-muted:#888;--accent:#10b981;--accent2:#06d6a0;--accent-glow:rgba(16,185,129,0.3);--gradient:linear-gradient(135deg,#10b981,#06d6a0,#3b82f6);--border:rgba(255,255,255,0.08);--radius:12px;--font:'Inter',sans-serif;--mono:'JetBrains Mono',monospace}
[data-theme="light"]{--bg:#f5f5fa;--bg-card:rgba(255,255,255,0.9);--bg-surface:#fff;--text:#1a1a2e;--text-muted:#666;--border:rgba(0,0,0,0.08);--accent-glow:rgba(16,185,129,0.15)}
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:var(--font);background:var(--bg);color:var(--text);min-height:100vh}
.container{max-width:1100px;margin:0 auto;padding:0 1.5rem}
.navbar{position:sticky;top:0;z-index:100;background:rgba(10,10,15,0.8);backdrop-filter:blur(20px);border-bottom:1px solid var(--border);padding:0.75rem 0}
[data-theme="light"] .navbar{background:rgba(245,245,250,0.85)}
.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:1rem}
.brand{text-decoration:none;color:var(--text);font-weight:700;font-size:1.25rem;display:flex;align-items:center;gap:0.5rem}
.brand span{background:var(--gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.nav-links{display:flex;gap:0.5rem;align-items:center;flex-wrap:wrap}
.nav-links a{text-decoration:none;color:var(--text-muted);font-size:0.9rem;padding:0.4rem 0.75rem;border-radius:8px;transition:all 0.2s}
.nav-links a:hover,.nav-links a.active{color:var(--text);background:var(--accent-glow)}
.kofi-link{color:#ff5e5b !important;font-weight:600}
.theme-btn{background:none;border:1px solid var(--border);width:36px;height:36px;border-radius:50%;cursor:pointer;font-size:1.1rem;display:flex;align-items:center;justify-content:center;transition:all 0.2s}
.theme-btn:hover{border-color:var(--accent);transform:scale(1.1)}
.hero{text-align:center;padding:2rem 0 1.5rem}
.hero h1{font-size:clamp(2rem,5vw,3rem);font-weight:800;margin-bottom:0.5rem}
.gradient-text{background:var(--gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero-sub{color:var(--text-muted);font-size:1rem;max-width:500px;margin:0 auto}
.glass-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:1.5rem;margin-bottom:1.5rem;backdrop-filter:blur(10px)}
.mt-2{margin-top:0.5rem}.mt-3{margin-top:1rem}.mt-4{margin-top:1.5rem}
.text-muted{color:var(--text-muted)}

/* Lab Layout */
.lab-layout{display:grid;grid-template-columns:260px 1fr;gap:1.5rem;margin-top:1rem}
.element-shelf h3{font-size:0.95rem;margin-bottom:0.75rem}
.element-grid,.compound-grid{display:flex;flex-wrap:wrap;gap:6px}
.element-chip{padding:6px 12px;background:var(--bg-surface);border:1px solid var(--border);border-radius:8px;font-size:0.8rem;font-weight:600;cursor:grab;transition:all 0.2s;user-select:none}
.element-chip:hover{border-color:var(--accent);transform:scale(1.05);box-shadow:0 0 12px var(--accent-glow)}
.element-chip.dragging{opacity:0.5}
.element-chip[data-cat="metal"]{border-left:3px solid #3b82f6}
.element-chip[data-cat="nonmetal"]{border-left:3px solid #ef4444}
.element-chip[data-cat="gas"]{border-left:3px solid #f59e0b}
.element-chip[data-cat="acid"]{border-left:3px solid #ec4899}
.element-chip[data-cat="base"]{border-left:3px solid #8b5cf6}
.element-chip[data-cat="compound"]{border-left:3px solid #06d6a0}

/* Beaker */
.beaker-container{display:flex;flex-direction:column;align-items:center;gap:1rem}
.beaker{width:200px;height:260px;border:3px solid var(--border);border-top:none;border-radius:0 0 30px 30px;position:relative;overflow:hidden;background:var(--bg-surface);transition:border-color 0.3s}
.beaker::before{content:'';position:absolute;top:-3px;left:-20px;right:-20px;height:3px;background:var(--border)}
.beaker.has-contents{border-color:var(--accent)}
.beaker-liquid{position:absolute;bottom:0;left:0;right:0;height:0;transition:height 0.5s ease,background 0.5s ease;border-radius:0 0 27px 27px}
.beaker-label{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;color:var(--text-muted);font-size:0.8rem;text-align:center;padding:1rem;pointer-events:none}
.bubbles{position:absolute;bottom:0;left:0;right:0;height:100%;pointer-events:none}
.bubble{position:absolute;width:8px;height:8px;border-radius:50%;background:rgba(255,255,255,0.3);animation:bubbleUp 2s ease-in infinite}
@keyframes bubbleUp{0%{bottom:0;opacity:0.8;transform:translateX(0)}50%{opacity:0.5}100%{bottom:100%;opacity:0;transform:translateX(20px)}}

.beaker-info{width:100%;font-size:0.85rem}
.info-row{display:flex;justify-content:space-between;padding:0.3rem 0;color:var(--text-muted)}
.info-row span:last-child{font-weight:600;color:var(--text);font-family:var(--mono)}
.temp-slider{width:100%;margin:0.3rem 0;-webkit-appearance:none;height:6px;border-radius:3px;background:linear-gradient(to right,#3b82f6,#f59e0b,#ef4444);outline:none;cursor:pointer}
.temp-slider::-webkit-slider-thumb{-webkit-appearance:none;width:16px;height:16px;border-radius:50%;background:#fff;box-shadow:0 2px 6px rgba(0,0,0,0.3);cursor:pointer}
.ph-bar{width:100%;height:12px;border-radius:6px;background:linear-gradient(to right,#ef4444,#f97316,#eab308,#22c55e,#3b82f6,#6366f1,#8b5cf6);position:relative;margin:0.3rem 0}
.ph-indicator{position:absolute;top:-3px;width:4px;height:18px;background:#fff;border-radius:2px;transform:translateX(-50%);box-shadow:0 0 8px rgba(255,255,255,0.5);transition:left 0.3s}
.beaker-contents-list{display:flex;flex-wrap:wrap;gap:4px;margin-top:0.3rem}
.beaker-contents-list .chip{padding:2px 8px;background:var(--accent-glow);border-radius:4px;font-size:0.7rem;font-weight:600;color:var(--accent)}
.beaker-actions{display:flex;gap:0.5rem;width:100%}
.beaker-actions .btn{flex:1;font-size:0.85rem;padding:0.6rem}

/* Reaction Result */
.reaction-result{margin-top:1rem}
.reaction-equation{font-family:var(--mono);font-size:1.1rem;font-weight:700;padding:1rem;background:var(--bg-surface);border-radius:8px;text-align:center;margin:0.75rem 0;letter-spacing:1px}
.reaction-desc{color:var(--text-muted);font-size:0.9rem;line-height:1.7}
.reaction-type-badge{display:inline-block;padding:4px 12px;border-radius:20px;font-size:0.75rem;font-weight:600;margin-top:0.75rem;background:var(--accent-glow);color:var(--accent)}
.reaction-anim{height:60px;display:flex;align-items:center;justify-content:center;gap:8px;margin-top:0.5rem}
.reaction-anim .spark{width:6px;height:6px;border-radius:50%;animation:spark 0.8s ease infinite}
@keyframes spark{0%,100%{transform:scale(1);opacity:0.8}50%{transform:scale(2);opacity:0.3}}

/* Equation Balancer */
.eq-input-row{display:flex;gap:0.5rem}
.eq-input-row input{flex:1;padding:0.7rem 1rem;background:var(--bg-surface);border:1px solid var(--border);border-radius:8px;color:var(--text);font-family:var(--mono);font-size:0.95rem;outline:none}
.eq-input-row input:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-glow)}
.balanced-result{font-family:var(--mono);font-size:1.1rem;padding:1rem;background:var(--bg-surface);border-radius:8px;text-align:center;min-height:50px;display:flex;align-items:center;justify-content:center}
.balanced-result .coeff{color:var(--accent);font-weight:800;font-size:1.3rem;margin-right:2px}

/* pH Scale */
.ph-explorer{max-width:600px;margin:0 auto}
.ph-scale{display:flex;border-radius:8px;overflow:hidden;height:40px}
.ph-block{flex:1;display:flex;align-items:center;justify-content:center;font-size:0.65rem;font-weight:700;color:#fff;cursor:pointer;transition:transform 0.2s;text-shadow:0 1px 2px rgba(0,0,0,0.3)}
.ph-block:hover{transform:scaleY(1.3);z-index:2}
.ph-info{text-align:center;font-size:0.85rem;color:var(--text-muted);min-height:40px}

/* Buttons */
.btn{padding:0.6rem 1.2rem;border:none;border-radius:8px;cursor:pointer;font-family:var(--font);font-weight:600;font-size:0.9rem;transition:all 0.2s}
.btn-primary{background:var(--gradient);color:#fff}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 4px 20px var(--accent-glow)}
.btn-secondary{background:transparent;color:var(--text);border:1px solid var(--border)}
.btn-secondary:hover{border-color:var(--accent);color:var(--accent)}

/* Info */
.info-section{margin:2rem 0}
.info-section h2{text-align:center;margin-bottom:1.5rem}
.info-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1rem}
.info-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem;transition:all 0.3s}
.info-card:hover{border-color:var(--accent);transform:translateY(-3px)}
.info-card h3{font-size:1rem;margin-bottom:0.5rem}
.info-card p{font-size:0.85rem;color:var(--text-muted);line-height:1.6}

/* Footer */
.footer{margin-top:3rem;border-top:1px solid var(--border);padding:2rem 0}
.footer-inner{display:flex;flex-wrap:wrap;gap:2rem;justify-content:space-between}
.footer-brand span{font-weight:700;font-size:1.1rem}
.footer-brand p{color:var(--text-muted);font-size:0.85rem;margin-top:0.3rem}
.footer-brand a{color:var(--accent);text-decoration:none}
.footer-links-grid{display:flex;gap:3rem}
.footer-links-grid h4{font-size:0.85rem;margin-bottom:0.75rem}
.footer-links-grid a{display:block;color:var(--text-muted);text-decoration:none;font-size:0.85rem;margin-bottom:0.4rem;transition:color 0.2s}
.footer-links-grid a:hover{color:var(--accent)}
.copyright{width:100%;text-align:center;color:var(--text-muted);font-size:0.8rem;margin-top:1rem;padding-top:1rem;border-top:1px solid var(--border)}

@media(max-width:768px){.nav-links{display:none}.lab-layout{grid-template-columns:1fr}.beaker{width:160px;height:200px}.eq-input-row{flex-direction:column}.builder-layout{grid-template-columns:1fr !important}.molecule-controls{flex-direction:column}}

/* 3D Molecule Viewer */
.molecule-controls{display:flex;gap:0.75rem;align-items:center;flex-wrap:wrap}
.molecule-controls select{padding:0.5rem 1rem;background:var(--bg-surface);border:1px solid var(--border);border-radius:8px;color:var(--text);font-family:var(--font);font-size:0.9rem;outline:none;cursor:pointer}
.molecule-controls select:focus{border-color:var(--accent)}
.toggle-label{display:flex;align-items:center;gap:0.4rem;font-size:0.85rem;color:var(--text-muted);cursor:pointer;user-select:none}
.toggle-label input[type="checkbox"]{accent-color:var(--accent);width:16px;height:16px;cursor:pointer}
.molecule-info{font-size:0.85rem;color:var(--text-muted);padding:0.75rem;background:var(--bg-surface);border-radius:8px;text-align:center}
.molecule-info strong{color:var(--accent)}

/* Compound Builder */
.builder-layout{display:grid;grid-template-columns:180px 1fr;gap:1rem}
.atom-palette{background:var(--bg-surface);border-radius:var(--radius);padding:1rem;border:1px solid var(--border)}
.atom-palette h4{font-size:0.85rem;color:var(--text-muted);margin-bottom:0.5rem}
.atom-chips{display:flex;flex-wrap:wrap;gap:4px}
.atom-chips .element-chip{padding:4px 10px;font-size:0.75rem;cursor:pointer !important}
.atom-chips .element-chip.selected{border-color:var(--accent);background:var(--accent-glow);color:var(--accent)}
.bond-selector{display:flex;flex-direction:column;gap:4px}
.bond-selector button{font-size:0.75rem;padding:0.4rem 0.6rem;text-align:left}
.bond-selector button.active{border-color:var(--accent);color:var(--accent);background:var(--accent-glow)}
.builder-actions{display:flex;flex-direction:column;gap:4px}
.builder-actions .btn{font-size:0.75rem;padding:0.4rem}
.builder-workspace{min-height:300px}
.builder-status{font-size:0.85rem;padding:0.5rem;text-align:center}
.form-select{padding:0.5rem;background:var(--bg-surface);border:1px solid var(--border);border-radius:8px;color:var(--text);outline:none;font-family:var(--font)}
.form-select:focus{border-color:var(--accent)}