body{color:#214b72;font-family:'Trebuchet MS',Arial,sans-serif;background:radial-gradient(ellipse at 12% 15%,#fff9 0,transparent 35%),linear-gradient(145deg,#b8e9fc,#e4f5ed 65%,#fff1d6)}
.arithmetic-app{width:100%;max-width:1250px;padding:24px;margin:0 auto}
.arithmetic-app header{margin:28px 0 20px;text-align:center}
.arithmetic-app h1{font-family:inherit;color:#214b72;font-size:clamp(30px,4vw,48px);letter-spacing:-1px}
.arithmetic-app .tab-shell{background:transparent;border:0;box-shadow:none;overflow:visible}
.arithmetic-app .practice-tabs{display:flex;justify-content:center;flex-wrap:wrap;gap:10px;background:transparent;border:0;padding:0;margin:22px 0}
.arithmetic-app .tab-button{bottom:0;min-height:46px;border:2px solid white;border-radius:17px;background:#ffffffa8;color:#214b72;box-shadow:0 6px 14px #24567e10;padding:12px 20px;font:bold 16px 'Trebuchet MS',sans-serif}
.arithmetic-app .tab-button.is-active{background:#5369d7;color:white}
.arithmetic-app .tab-button .tab-number{display:inline;white-space:nowrap;width:auto;height:auto;min-width:0;background:transparent;color:inherit;font:inherit;border:0}
.arithmetic-app .tab-number:after{content:' ·'}
.arithmetic-app .tab-panel{padding:0;background:transparent}
.arithmetic-app .method-panel,.arithmetic-app .solution-panel,.arithmetic-app .test-card,.arithmetic-app #panelVideo{border:3px solid white;border-radius:26px;padding:24px;background:#ffffffdc;box-shadow:0 18px 38px #24567e18;margin:0 0 20px}
.arithmetic-app .method-panel{background:linear-gradient(180deg,#fafdff,#eefaff)}
.arithmetic-app .method-header{margin-bottom:12px;gap:15px;flex-wrap:wrap}
.arithmetic-app .method-header h2,.arithmetic-app .solution-panel h2{color:#214b72;font-size:25px}
.arithmetic-app .new-button{margin-top:12px;background:#c5e3c2;border:2px solid #39834b;color:#215b32;box-shadow:0 4px 10px #24567e14;border-radius:14px;padding:12px 20px}
.arithmetic-app .check-button{background:#5369d7;border:2px solid white;border-radius:16px;padding:12px 20px;color:white;font: bold 16px 'Trebuchet MS',sans-serif}
.arithmetic-app .ghost-button{background:#e9edff;border:2px solid white;border-radius:16px;color:#214b72;padding:12px 20px}
.arithmetic-app .method-actions{margin-top:18px;gap:10px;flex-wrap:wrap}
.arithmetic-app .tip{margin:0 0 20px}
.arithmetic-app .method-grid-wrap{margin:12px auto;overflow-x:auto}
.arithmetic-app .video-placeholder{min-height:320px;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center}
.arithmetic-app .video-placeholder>span{font-size:56px;color:#5369d7}
.arithmetic-app .test-card{text-align:center;margin:0 auto 20px}
.arithmetic-app .answer-form-inline{justify-content:center;flex-wrap:wrap;gap:16px}
body[data-operation="division"] .arithmetic-app .answer-form-inline input{font-size:22px;height:48px;line-height:1.3;width:170px;max-width:100%}
.arithmetic-app .inline-question{font-size:clamp(24px,4vw,34px);color:#214b72}
.arithmetic-app .message:empty{display:none}
.arithmetic-app .message{border-radius:16px;padding:16px;margin:16px 0;font-size:17px}
.arithmetic-app .message.good{background:#e1f5e8;color:#187858}
.arithmetic-app .message.bad{background:#ffe4e7;color:#aa3045}
.arithmetic-options{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin:0 0 20px}
.arithmetic-options label{display:flex;align-items:center;gap:9px;padding:12px 16px;border:2px solid white;border-radius:14px;background:#ffffffb8;margin:0;color:#214b72}
.arithmetic-options input{width:19px;height:19px;accent-color:#5369d7;padding:0}
.arithmetic-options label:has(input:checked){background:#e9edff;border-color:#a1aee6}
.arithmetic-options label:has(input:disabled){opacity:.8}
.arithmetic-app .method-header .arithmetic-options{margin:0;gap:8px}
.arithmetic-app .method-header .arithmetic-options label{padding:9px 12px;font-size:14px}
.arithmetic-app .method-header .new-button{margin-top:0}
.arithmetic-app .test-header{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap}
.arithmetic-app .test-header h2{margin:0}
.arithmetic-toolbar{display:flex;justify-content:center;align-items:center;gap:14px;flex-wrap:wrap;margin:22px 0}
.arithmetic-app .arithmetic-toolbar .practice-tabs,.arithmetic-toolbar .arithmetic-options{margin:0}
.arithmetic-app .method-grid{--method-label-width:68px;--method-digit-width:54px}
.arithmetic-app .method-grid.is-compact{--method-label-width:52px;--method-digit-width:44px}
.arithmetic-app .method-grid .method-cell.is-comma{width:100%;min-width:0;padding:0;justify-items:end;text-align:right}
@media(max-width:600px){.arithmetic-app .method-grid{--method-label-width:56px;--method-digit-width:44px}.arithmetic-app .method-grid.is-compact{--method-label-width:42px;--method-digit-width:36px}}
@media(max-width:600px){.arithmetic-app{padding:16px}.arithmetic-app .tab-button{font-size:14px;padding:10px 12px}.arithmetic-app .method-panel,.arithmetic-app .test-card{padding:16px}.arithmetic-app .method-header h2{font-size:23px}}