:root{--bg: #f5f6fa;--card: #ffffff;--text: #0f172a;--muted: #64748b;--subtle: #94a3b8;--primary: #4f46e5;--primary-dark: #3730a3;--primary-text: #ffffff;--danger: #ef4444;--success: #10b981;--warning: #f59e0b;--border: #e2e8f0;--shadow: 0 1px 2px rgba(15, 23, 42, .04), 0 8px 24px rgba(15, 23, 42, .06);--radius: 12px;--radius-lg: 16px;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;color-scheme:light}*{box-sizing:border-box}html,body,#root{margin:0;padding:0;background:var(--bg);color:var(--text);min-height:100vh}body{font-size:16px;line-height:1.5;-webkit-font-smoothing:antialiased}button{font-family:inherit;cursor:pointer}a{color:var(--primary)}.app{max-width:720px;margin:0 auto;padding:24px 16px 64px}.topbar{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px;gap:12px}.brand{font-size:22px;font-weight:800;color:var(--text);text-decoration:none;letter-spacing:-.5px}.brand span{color:var(--primary)}.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:10px 18px;border-radius:var(--radius);font-size:15px;font-weight:600;border:1px solid transparent;background:var(--primary);color:var(--primary-text);transition:opacity .12s ease,transform 80ms ease}.btn:hover{opacity:.92}.btn:active{transform:translateY(1px)}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-secondary{background:var(--card);color:var(--text);border-color:var(--border)}.btn-danger{background:var(--danger)}.btn-ghost{background:transparent;color:var(--primary)}.btn-row{display:flex;gap:10px;flex-wrap:wrap}.input,.textarea{width:100%;padding:12px 14px;border-radius:var(--radius);border:1px solid var(--border);background:var(--card);font-size:15px;color:var(--text);font-family:inherit}.textarea{min-height:120px;resize:vertical}.input:focus,.textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px #4f46e526}.label{display:block;font-size:13px;font-weight:600;color:var(--muted);margin-bottom:6px}.field{margin-bottom:14px}.card{background:var(--card);border-radius:var(--radius-lg);padding:18px;box-shadow:var(--shadow)}.card+.card{margin-top:12px}.muted{color:var(--muted);font-size:14px}.empty{text-align:center;padding:56px 16px}.empty h2{margin:0 0 8px;font-size:22px}.empty p{color:var(--muted);margin:0 0 16px}.error{background:#fef2f2;color:var(--danger);border:1px solid #fecaca;border-radius:var(--radius);padding:10px 14px;font-size:14px;margin-bottom:14px}.deck-row{display:flex;align-items:center;justify-content:space-between;text-decoration:none;color:inherit}.deck-row .chev{color:var(--subtle);font-size:28px;line-height:1}.deck-row strong{font-size:17px}.card-front{font-weight:600}.card-divider{height:1px;background:var(--border);margin:10px 0}.card-back{color:var(--muted);font-size:14px}.progress{display:flex;gap:12px;align-items:center;margin-bottom:20px}.progress-track{flex:1;height:6px;background:var(--border);border-radius:3px;overflow:hidden}.progress-fill{height:100%;background:var(--primary);transition:width .2s ease}.progress-text{font-size:13px;color:var(--muted);font-weight:600;min-width:56px;text-align:right}.flip-wrap{perspective:1200px;height:320px;margin-bottom:18px;cursor:pointer;-webkit-user-select:none;user-select:none}.flip{position:relative;width:100%;height:100%;transition:transform .38s cubic-bezier(.2,.8,.2,1);transform-style:preserve-3d}.flip.flipped{transform:rotateY(180deg)}.flip-face{position:absolute;top:0;right:0;bottom:0;left:0;border-radius:var(--radius-lg);background:var(--card);box-shadow:var(--shadow);padding:32px;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;-webkit-backface-visibility:hidden;backface-visibility:hidden;gap:12px}.flip-face.back{transform:rotateY(180deg)}.flip-label{font-size:11px;letter-spacing:1.5px;color:var(--subtle);font-weight:700}.flip-text{font-size:26px;font-weight:600}.flip-hint{font-size:13px;color:var(--subtle);margin-top:8px}.modal-backdrop{position:fixed;top:0;right:0;bottom:0;left:0;background:#0f172a73;display:flex;align-items:center;justify-content:center;padding:16px;z-index:50}.modal{width:100%;max-width:460px;background:var(--card);border-radius:var(--radius-lg);padding:22px;box-shadow:var(--shadow)}.modal h3{margin:0 0 14px;font-size:18px}.auth-wrap{max-width:380px;margin:64px auto 0}.auth-wrap h1{text-align:center;font-size:28px;margin-bottom:24px;letter-spacing:-.5px}.auth-wrap .card{padding:24px}.auth-wrap .switch{text-align:center;margin-top:16px;font-size:14px;color:var(--muted)}.landing{max-width:460px;margin:32px auto 0;display:flex;flex-direction:column;gap:36px}.landing .auth-wrap{max-width:460px;margin:0 auto}.landing .auth-wrap .card{padding:32px 28px}.landing .auth-wrap .input{padding:14px 16px;font-size:16px;min-height:48px}.landing .auth-wrap .btn{min-height:52px;font-size:16px}.landing .auth-wrap .label{font-size:14px}.landing .auth-wrap .switch{font-size:15px;margin-top:18px}.hero{text-align:center}.hero-title{font-size:44px;font-weight:800;letter-spacing:-1.5px;margin:8px 0 12px;color:var(--text)}.hero-title span{color:var(--primary)}.hero-tagline{font-size:17px;color:var(--muted);margin:0 0 20px;line-height:1.45}.hero-bullets{list-style:none;padding:0;margin:0;text-align:left;display:inline-block}.hero-bullets li{font-size:14.5px;color:var(--muted);margin-bottom:8px;padding-left:22px;position:relative}.hero-bullets li:before{content:"✓";color:var(--primary);font-weight:700;position:absolute;left:0;top:0}.hero-bullets li strong{color:var(--text);font-weight:600}.spinner{display:inline-block;width:20px;height:20px;border:2.5px solid var(--border);border-top-color:var(--primary);border-radius:50%;animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.center-screen{min-height:60vh;display:flex;align-items:center;justify-content:center}