.stc-tool{background:var(--surface,#fff);border:1px solid var(--border,#e5e7eb);border-radius:16px;box-shadow:0 2px 12px rgba(0,0,0,.06);overflow:hidden;margin-bottom:2rem;}
.stc-bar{display:flex;flex-wrap:wrap;align-items:center;gap:1rem;padding:1rem 1.25rem;background:var(--surface-muted,#f9fafb);border-bottom:1px solid var(--border,#e5e7eb);}
.stc-bar-group{display:flex;flex-direction:column;gap:0.25rem;}
.stc-bar-label{font-size:0.8125rem;font-weight:600;color:var(--text-muted,#6b7280);}
.stc-select{padding:0.5rem 2rem 0.5rem 0.75rem;font-size:0.9375rem;color:var(--text-main,#111);background:var(--surface,#fff);border:1px solid var(--border,#e5e7eb);border-radius:10px;cursor:pointer;appearance:auto;}
.stc-actions{display:flex;flex-wrap:wrap;gap:0.5rem;margin-left:auto;}
.stc-btn{padding:0.5rem 1rem;font-size:0.875rem;font-weight:600;border-radius:10px;cursor:pointer;transition:background .15s,color .15s,transform .08s;border:none;}
.stc-btn-ghost{color:var(--text-muted,#6b7280);background:transparent;}
.stc-btn-ghost:hover{color:var(--text-main,#111);background:var(--border,#e5e7eb);}
.stc-btn-primary{color:#fff;background:var(--primary,#5e35b1);}
.stc-btn-primary:hover{background:var(--primary-dark,#4527a0);}
.stc-btn:active{transform:scale(0.98);}
.stc-sets{display:grid;grid-template-columns:1fr;gap:1rem;padding:1.25rem 1.25rem 0;}
.stc-field{display:flex;flex-direction:column;gap:0.375rem;}
.stc-label{font-size:0.875rem;font-weight:600;color:var(--text-main,#111);}
.stc-input{width:100%;padding:0.75rem 1rem;font-size:1rem;line-height:1.5;color:var(--text-main,#111);background:var(--surface,#fff);border:1px solid var(--border,#e5e7eb);border-radius:10px;box-sizing:border-box;transition:border-color .15s,box-shadow .15s;}
.stc-input:focus{outline:none;border-color:var(--primary,#5e35b1);box-shadow:0 0 0 3px rgba(94,53,177,0.12);}
.stc-input::placeholder{color:var(--text-muted,#9ca3af);}
.stc-hint{font-size:0.8125rem;color:var(--text-muted,#6b7280);margin:0.5rem 1.25rem 0;padding-bottom:1rem;}
.stc-venn{padding:1.25rem;border-top:1px solid var(--border,#e5e7eb);}
.stc-venn-wrap{overflow-x:auto;margin-bottom:1rem;border-radius:10px;background:var(--surface-muted,#f9fafb);}
#stc-canvas{display:block;max-width:100%;height:auto;}
.stc-legend{display:flex;flex-wrap:wrap;justify-content:center;gap:1.25rem;}
.stc-legend-item{display:inline-flex;align-items:center;gap:0.5rem;font-size:0.9375rem;color:var(--text-main,#111);}
.stc-legend-dot{width:14px;height:14px;border-radius:50%;border:2px solid currentColor;}
.stc-dot-a{background:rgba(255,99,132,0.5);color:rgba(255,99,132,1);}
.stc-dot-b{background:rgba(54,162,235,0.5);color:rgba(54,162,235,1);}
.stc-dot-c{background:rgba(255,206,86,0.5);color:rgba(255,206,86,1);}
.stc-ops{padding:1.25rem;border-top:1px solid var(--border,#e5e7eb);}
.stc-ops-head{font-size:1.125rem;font-weight:700;margin:0 0 1rem;color:var(--text-main,#111);}
.stc-op-list{list-style:none;margin:0;padding:0;}
.stc-op{display:flex;flex-wrap:wrap;align-items:baseline;gap:0.5rem 1rem;padding:0.75rem 0;border-bottom:1px solid var(--border,#e5e7eb);}
.stc-op:last-child{border-bottom:none;}
.stc-op-name{font-size:0.9375rem;font-weight:600;color:var(--text-main,#111);min-width:10rem;}
.stc-op-result{font-size:0.9375rem;color:var(--text-muted,#6b7280);word-break:break-word;flex:1;min-width:0;}
.stc-ops-three{padding:1.25rem;border-top:1px solid var(--border,#e5e7eb);}
.stc-ops-three[hidden]{display:none;}
.stc-props{padding:1.25rem;border-top:1px solid var(--border,#e5e7eb);background:var(--surface-muted,#f9fafb);}
.stc-props-head{font-size:1.125rem;font-weight:700;margin:0 0 1rem;color:var(--text-main,#111);}
.stc-dl{margin:0;display:grid;grid-template-columns:auto 1fr;gap:0.5rem 1.5rem;align-items:center;}
.stc-dl-row{display:contents;}
.stc-dl-row dt{font-size:0.9375rem;font-weight:600;color:var(--text-main,#111);}
.stc-dl-row dd{font-size:0.9375rem;color:var(--text-muted,#6b7280);margin:0;}
.stc-edu{padding:1.5rem 1.25rem;border-top:1px solid var(--border,#e5e7eb);}
.stc-edu-head{font-size:1.0625rem;font-weight:600;margin:1rem 0 0.5rem;color:var(--text-main,#111);}
.stc-edu-head:first-child{margin-top:0;}
.stc-edu-p{font-size:0.9375rem;color:var(--text-muted,#6b7280);line-height:1.6;margin:0 0 0.75rem;}
.stc-edu-list{font-size:0.9375rem;color:var(--text-muted,#6b7280);line-height:1.6;margin:0 0 1rem;padding-left:1.25rem;}
.stc-edu-list li{margin-bottom:0.25rem;}
@media (min-width:480px){.stc-sets{grid-template-columns:1fr 1fr;}.stc-actions{margin-left:0;}}
@media (min-width:768px){.stc-sets{grid-template-columns:repeat(4,1fr);padding:1.5rem 1.5rem 0;}.stc-hint{margin-left:1.5rem;padding-bottom:1.5rem;}.stc-bar{padding:1rem 1.5rem;}.stc-venn,.stc-ops,.stc-ops-three,.stc-props,.stc-edu{padding:1.5rem;}.stc-venn-wrap{max-width:600px;margin-left:auto;margin-right:auto;}}
@media (max-width:767px){#stc-canvas{max-height:280px;}}