.pi-root{width:100%;min-height:100%;display:flex;justify-content:center;align-items:flex-start;padding:24px 16px;box-sizing:border-box;font-family:-apple-system,PingFang SC,Helvetica Neue,sans-serif;color:#2d3748}.pi-card{width:100%;max-width:720px;background:#fff;border-radius:20px;box-shadow:0 2px 12px #0000000f;padding:24px;box-sizing:border-box}.pi-btn{font-family:inherit;font-size:20px;min-height:56px;border-radius:14px;border:none;padding:0 24px;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:8px;width:100%;box-sizing:border-box;touch-action:manipulation;transition:opacity .15s ease,transform .1s ease}.pi-btn:active{transform:scale(.98)}.pi-btn:disabled{opacity:.6;cursor:default}.pi-btn-primary{background:#3182ce;color:#fff}.pi-btn-secondary{background:#f7fafc;color:#2d3748;border:1px solid #e2e8f0}.pi-btn-big{font-size:22px;min-height:72px}.pi-idle{display:flex;flex-direction:column;gap:16px;padding:32px 8px}.pi-camera{display:flex;flex-direction:column}.pi-viewfinder-wrap{position:relative;width:100%;border-radius:16px;overflow:hidden;background:#000}.pi-video{width:100%;height:auto;display:block;aspect-ratio:4 / 3;object-fit:cover;background:#000}.pi-viewfinder-frame{position:absolute;top:10%;right:8%;bottom:10%;left:8%;border:3px dashed rgba(255,255,255,.85);border-radius:12px;pointer-events:none;display:flex;align-items:flex-end;justify-content:center;padding-bottom:10px}.pi-viewfinder-hint{color:#fff;font-size:18px;background:#00000073;padding:6px 14px;border-radius:999px}.pi-camera-controls{display:flex;gap:12px;padding:16px;background:#000}.pi-camera-controls .pi-btn-secondary{flex:0 0 auto;width:auto;min-width:100px;background:#ffffff26;color:#fff;border-color:#ffffff4d}.pi-camera-controls .pi-btn-shutter{flex:1 1 auto}.pi-fallback{display:flex;flex-direction:column;gap:16px;padding:24px 8px}.pi-fallback-reason{font-size:18px;color:#718096;line-height:1.6;margin:0}.pi-hidden-input{position:absolute;width:1px;height:1px;overflow:hidden;opacity:0;pointer-events:none}.pi-crop{display:flex;flex-direction:column;gap:16px}.pi-crop-hint{margin:0;font-size:20px;text-align:center;color:#2d3748}.pi-crop-stage{position:relative;width:100%;border-radius:12px;overflow:hidden;background:#1a202c;touch-action:none;user-select:none;-webkit-user-select:none}.pi-crop-imghost{width:100%;line-height:0}.pi-crop-box{position:absolute;box-shadow:0 0 0 9999px #0000008c;border:2px solid #ffffff;border-radius:4px;pointer-events:none}.pi-crop-handle{position:absolute;width:28px;height:28px;background:#fff;border:2px solid #3182ce;border-radius:50%;pointer-events:none}.pi-crop-handle-tl{left:0;top:0;transform:translate(-50%,-50%)}.pi-crop-handle-tr{left:100%;top:0;transform:translate(-50%,-50%)}.pi-crop-handle-bl{left:0;top:100%;transform:translate(-50%,-50%)}.pi-crop-handle-br{left:100%;top:100%;transform:translate(-50%,-50%)}.pi-crop-actions{display:flex;gap:12px}.pi-crop-actions .pi-btn{flex:1 1 0}:root{--color-bg: #f7fafc;--color-card: #ffffff;--color-primary: #3182ce;--color-primary-dark: #2b6cb0;--color-accent: #e53e3e;--color-text: #2d3748;--color-text-secondary: #718096;--radius-card: 20px;--shadow-card: 0 2px 12px rgba(0, 0, 0, .06);--font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", sans-serif;--font-size-body: 20px;--font-size-title: 26px;--font-size-hint: 24px;--button-height-min: 56px;--content-max-width: 720px}*,*:before,*:after{box-sizing:border-box}html,body{margin:0;padding:0}body{background:var(--color-bg);color:var(--color-text);font-family:var(--font-family);font-size:var(--font-size-body);line-height:1.65;-webkit-tap-highlight-color:transparent;overscroll-behavior-y:contain;min-height:100vh}#root{max-width:var(--content-max-width);margin:0 auto;min-height:100vh;padding:max(16px,env(safe-area-inset-top)) max(16px,env(safe-area-inset-right)) max(16px,env(safe-area-inset-bottom)) max(16px,env(safe-area-inset-left))}button{font-family:inherit;color:inherit;border:none;background:none;cursor:pointer;-webkit-tap-highlight-color:transparent}button:disabled{cursor:not-allowed;opacity:.6}p{margin:0 0 .6em}p:last-child{margin-bottom:0}h1,h2,h3{margin:0}img,svg{max-width:100%;height:auto}.card{background:var(--color-card);border-radius:var(--radius-card);box-shadow:var(--shadow-card);padding:24px;margin-bottom:20px;position:relative}.btn-primary{display:inline-flex;align-items:center;justify-content:center;min-height:var(--button-height-min);padding:0 28px;background:var(--color-primary);color:#fff;font-size:20px;font-weight:600;border-radius:14px;transition:background .15s ease,transform .1s ease;width:100%}.btn-primary:active{background:var(--color-primary-dark);transform:scale(.98)}.app-shell{display:flex;flex-direction:column;min-height:100%}.app-header{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:4px 0 20px}.app-title{font-size:var(--font-size-title);font-weight:700;color:var(--color-text)}.reset-button{flex-shrink:0;min-height:44px;padding:0 16px;border-radius:12px;background:var(--color-card);box-shadow:var(--shadow-card);color:var(--color-text-secondary);font-size:17px;font-weight:600}.reset-button:active{transform:scale(.97)}.idle-panel{display:flex;flex-direction:column;align-items:center;gap:24px;padding-top:8px;text-align:center}.idle-tagline{font-size:var(--font-size-body);color:var(--color-text-secondary);max-width:560px}.step-flow{display:flex;flex-direction:column}.problem-card__category{display:inline-block;font-size:14px;font-weight:600;color:var(--color-primary);background:#ebf8ff;padding:4px 12px;border-radius:999px;margin-bottom:12px}.problem-card__text{font-size:var(--font-size-title);font-weight:700;color:var(--color-text);margin-bottom:16px}.problem-card__meta{display:flex;flex-direction:column;gap:12px}.problem-card__label{display:block;font-size:14px;font-weight:600;color:var(--color-text-secondary);margin-bottom:4px}.problem-card__known ul{margin:0;padding-left:1.2em}.problem-card__known li,.problem-card__goal p{font-size:18px;color:var(--color-text)}.step-card{padding-top:40px}.step-card__badge{position:absolute;top:-14px;left:20px;min-width:36px;height:36px;padding:0 8px;border-radius:50%;background:var(--color-primary);color:#fff;font-size:18px;font-weight:700;display:flex;align-items:center;justify-content:center;box-shadow:0 2px 8px #3182ce59}.step-card--locked .step-card__badge{background:var(--color-text-secondary);box-shadow:none}.step-card__hint-block{display:flex;flex-direction:column;gap:20px}.step-card__hint{font-size:var(--font-size-hint);font-weight:600;color:var(--color-text);line-height:1.5}.step-card__expand{animation:step-reveal .35s ease}@keyframes step-reveal{0%{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}.step-card__title{font-size:22px;font-weight:700;margin-bottom:14px;color:var(--color-text)}.step-card__svg{display:block;width:100%;margin-bottom:14px;border-radius:12px;background:#f7fafc}.step-card__explain{font-size:var(--font-size-body);color:var(--color-text)}.answer-reveal{text-align:center}.answer-reveal__encourage{font-size:18px;color:var(--color-text-secondary);margin-bottom:18px}.answer-reveal__value{font-size:34px;font-weight:800;color:var(--color-accent);margin-bottom:12px}.answer-reveal__check{font-size:18px;color:var(--color-text-secondary)}.error-card{text-align:center;border:1px solid #fed7d7}.error-card__message{font-size:var(--font-size-hint);color:var(--color-text);margin-bottom:20px}.loading{display:flex;flex-direction:column;align-items:center;gap:16px;padding:56px 16px}.loading__pen{width:160px;height:100px;overflow:visible}.loading__line{fill:none;stroke:var(--color-primary);stroke-width:4;stroke-linecap:round;stroke-dasharray:260;stroke-dashoffset:260;animation:loading-draw 1.8s ease-in-out infinite}.loading__tip{animation:loading-move 1.8s ease-in-out infinite}@keyframes loading-draw{0%{stroke-dashoffset:260}55%{stroke-dashoffset:0}to{stroke-dashoffset:0}}@keyframes loading-move{0%{transform:translate(6px,62px) rotate(25deg)}55%{transform:translate(108px,18px) rotate(25deg)}to{transform:translate(108px,18px) rotate(25deg)}}.loading__text{font-size:20px;color:var(--color-text-secondary);text-align:center;min-height:1.6em}