.tb64-section{margin-bottom:2rem;}
.tb64-card{background:var(--surface,#fff);border:1px solid var(--border,#e2e8f0);border-radius:16px;box-shadow:0 2px 12px rgba(0,0,0,0.06);overflow:hidden;}
.tb64-input-block{padding:1.25rem 1rem;border-bottom:1px solid var(--border,#e2e8f0);}
.tb64-output-block{padding:1.25rem 1rem;background:var(--surface-muted,#f8fafc);}
.tb64-label{display:block;font-size:0.8125rem;font-weight:600;letter-spacing:0.04em;color:var(--text-muted,#64748b);margin-bottom:0.5rem;}
.tb64-textarea{width:100%;min-height:160px;padding:0.875rem 1rem;font-size:0.9375rem;line-height:1.5;font-family:ui-monospace,monospace;color:var(--text-main,#0f172a);background:var(--surface,#fff);border:1px solid var(--border,#e2e8f0);border-radius:10px;resize:vertical;transition:border-color 0.2s,box-shadow 0.2s;-webkit-appearance:none;appearance:none;}
.tb64-textarea::placeholder{color:var(--text-muted,#94a3b8);}
.tb64-textarea:focus{outline:0;border-color:var(--primary,#2563eb);box-shadow:0 0 0 3px rgba(37,99,235,0.12);}
.tb64-output{min-height:100px;background:var(--surface,#fff);cursor:default;}
.tb64-link{display:inline-block;margin-top:0.5rem;font-size:0.875rem;color:var(--primary,#2563eb);background:none;border:none;cursor:pointer;padding:0;text-decoration:underline;text-underline-offset:2px;}
.tb64-link:hover{color:var(--primary-dark,#1d4ed8);}
.tb64-actions{display:flex;flex-wrap:wrap;gap:0.75rem;padding:1rem 1rem;background:var(--surface,#fff);border-bottom:1px solid var(--border,#e2e8f0);}
.tb64-btn{min-height:44px;padding:0.625rem 1.25rem;font-size:0.9375rem;font-weight:600;border-radius:10px;cursor:pointer;transition:background 0.2s,color 0.2s,border-color 0.2s,transform 0.1s;border:1px solid transparent;}
.tb64-btn:active{transform:scale(0.98);}
.tb64-btn-primary{color:#fff;background:var(--primary,#2563eb);border-color:var(--primary,#2563eb);}
.tb64-btn-primary:hover{background:var(--primary-dark,#1d4ed8);border-color:var(--primary-dark,#1d4ed8);}
.tb64-btn-secondary{color:var(--text-main,#0f172a);background:var(--surface-muted,#f1f5f9);border-color:var(--border,#e2e8f0);}
.tb64-btn-secondary:hover{background:var(--border,#e2e8f0);}
.tb64-btn-ghost{color:var(--primary,#2563eb);background:transparent;border-color:var(--border,#e2e8f0);}
.tb64-btn-ghost:hover{background:rgba(37,99,235,0.06);border-color:var(--primary,#2563eb);}
.tb64-feedback{display:block;min-height:1.25rem;margin-top:0.5rem;font-size:0.875rem;color:var(--text-muted,#64748b);}
.tb64-feedback.is-success{color:var(--success,#16a34a);}
.tb64-feedback.is-error{color:var(--danger,#dc2626);}
@media (min-width:768px){.tb64-input-block,.tb64-output-block{padding:1.5rem 1.5rem;}.tb64-textarea{min-height:200px;}.tb64-output{min-height:140px;}.tb64-actions{padding:1.25rem 1.5rem;gap:1rem;}}