*{box-sizing:border-box}body{margin:0;background:#f5f8fd;color:#18243a;font-family:Inter,Segoe UI,Arial,sans-serif;line-height:1.55}.topbar{position:sticky;top:0;z-index:50;background:#fff;border-bottom:1px solid #dfe7f2;box-shadow:0 3px 14px #18243a12}.nav{max-width:1180px;margin:auto;padding:9px 16px;display:flex;justify-content:space-between;align-items:center}.logo{display:flex;align-items:center;gap:9px;text-decoration:none;color:#15234a;font-weight:900}.logo-icon{display:grid;place-items:center;width:40px;height:40px;border-radius:12px;background:#15234a;color:#fff}.menu{display:flex;gap:18px}.menu a{color:#33425e;text-decoration:none;font-size:.9rem;font-weight:850}.hero{max-width:1180px;margin:22px auto 14px;padding:18px 16px;display:grid;grid-template-columns:205px 1fr;gap:25px;align-items:center}.hero-graphic{height:175px;border-radius:30px;background:linear-gradient(135deg,#e5efff,#fff4d8);border:1px solid #d8e3f2;position:relative;overflow:hidden}.student{position:absolute;font-size:76px;left:58px;bottom:5px;animation:bob 2.5s infinite}.book{position:absolute;font-size:35px;left:22px;bottom:22px;animation:float 3s infinite}.bubble{position:absolute;background:#fff;padding:6px 10px;border-radius:14px;font-weight:950;box-shadow:0 5px 15px #18243a20;animation:float 3s infinite}.one{top:15px;left:13px}.two{top:27px;right:14px;animation-delay:.4s}.three{bottom:17px;right:16px;animation-delay:.8s}.star{position:absolute;left:15px;top:80px;font-size:25px;animation:spin 3s linear infinite}@keyframes bob{50%{transform:translateY(-7px)}}@keyframes float{50%{transform:translateY(-7px)}}@keyframes spin{to{transform:rotate(360deg)}}.eyebrow{font-size:.76rem;font-weight:950;color:#31509b}.hero h1{font-size:clamp(1.8rem,5vw,3.2rem);line-height:1.03;color:#15234a;margin:8px 0}.subtitle{color:#5c6a81;font-size:1.05rem;margin:0 0 10px}.chips{display:flex;flex-wrap:wrap;gap:7px}.chips span{background:#fff;border:1px solid #dce5f1;border-radius:99px;padding:5px 9px;font-size:.8rem}.source-note{font-size:.76rem;color:#7a8799;margin:10px 0 0}.panel{max-width:1180px;margin:14px auto;padding:18px;background:#fff;border:1px solid #dfe7f2;border-radius:18px;box-shadow:0 5px 22px #18243a0b}.controls h2{margin:0 0 12px;color:#15234a}.control-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.control-grid label{font-size:.86rem;font-weight:850;color:#3d4c66}.control-grid select{display:block;width:100%;margin-top:5px;border:1px solid #cad6e6;border-radius:10px;background:#fff;padding:11px;font:inherit;color:#18243a}.actions{display:flex;flex-wrap:wrap;gap:9px;margin-top:15px}.actions button{border:0;border-radius:10px;padding:11px 14px;background:#edf2f9;color:#253654;font-weight:900;cursor:pointer}.actions button:hover{transform:translateY(-1px)}.actions .primary{background:#15234a;color:#fff}.start-note{margin-top:12px;background:#fff7da;border:1px solid #efd991;border-radius:10px;padding:10px}.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;text-align:center}.stats div{background:#f7f9fd;border-radius:12px;padding:9px}.stats b{display:block;font-size:1.28rem;color:#15234a}.stats small{color:#69768a}.progress{max-width:1180px;height:10px;margin:8px auto;background:#dce5f2;border-radius:99px;overflow:hidden}.progress div{height:100%;width:0;background:#15234a;transition:width .3s}.questions{max-width:1180px;margin:auto}.qcard{background:#fff;border:1px solid #dfe7f2;border-radius:17px;padding:16px;margin:14px 0;box-shadow:0 4px 18px #18243a09;transition:.2s}.qcard.correct{border-color:#299b56;animation:correct .45s}.qcard.wrong{border-color:#d9534f;animation:wrong .4s}@keyframes correct{45%{transform:scale(1.01)}}@keyframes wrong{25%,75%{transform:translateX(-5px)}50%{transform:translateX(5px)}}.qhead{display:flex;justify-content:space-between;align-items:center;gap:10px}.qnum{font-weight:950;color:#15234a}.tag{font-size:.7rem;background:#edf2f9;padding:4px 8px;border-radius:99px}.subtopic{font-size:.75rem;color:#68768a;margin-top:5px}.qtext{font-size:1.02rem;font-weight:750;margin:9px 0}.subparts{margin:8px 0;padding:9px 11px;background:#fafcff;border-left:4px solid #d5e0ef}.choices{display:grid;grid-template-columns:1fr 1fr;gap:8px}.choice{padding:11px;text-align:left;border:1px solid #ccd7e7;border-radius:10px;background:#fff;font-weight:750;cursor:pointer}.choice.selected{outline:3px solid #dbe5ff;background:#f1f5ff}.answer{width:100%;padding:11px;border:2px solid #ccd7e7;border-radius:10px;font:inherit}.answer.correct-input{border-color:#299b56;background:#eaf8ef;color:#145b2d}.answer.wrong-input{border-color:#d9534f;background:#fff0ef;color:#8b211e}.check-btn,.show-btn{margin-top:9px;border:0;border-radius:10px;padding:10px 13px;font-weight:900;cursor:pointer;background:#edf2f9;color:#253654}.feedback{min-height:24px;font-weight:900;margin-top:8px}.good{color:#19743b}.bad{color:#a52824}.show-answer{display:none;background:#f4f7fb;border-radius:10px;padding:9px;margin-top:8px}.result{text-align:center;background:#edf8f0;border-color:#b8dfc3}.hidden{display:none}.guide h2{color:#15234a}.guide h3{color:#304c79;margin-bottom:4px}.guide p,.guide li{font-size:.96rem}.formula{display:inline-block;background:#fff0a8;border:1px solid #e8cf63;border-radius:7px;padding:1px 7px;font-weight:900;color:#4c3a00}footer{text-align:center;padding:24px;color:#6b778b;font-size:.84rem}@media(max-width:720px){.hero{grid-template-columns:1fr;padding:15px}.hero-graphic{height:135px}.student{font-size:60px;left:42%}.control-grid{grid-template-columns:1fr 1fr}.stats{grid-template-columns:1fr 1fr}.choices{grid-template-columns:1fr}.actions button{flex:1 1 45%}.panel{margin:10px 9px;padding:14px}.progress{margin:8px 9px}.qcard{padding:13px}.menu{gap:9px}.menu a{font-size:.76rem}.logo-icon{width:34px;height:34px}}@media(max-width:420px){.control-grid{grid-template-columns:1fr}.actions button{flex-basis:100%}}@media print{.topbar,.hero-graphic,.controls,.stats,.progress,.guide,footer,.check-btn,.show-btn,.feedback{display:none!important}.panel,.qcard{box-shadow:none}.qcard{break-inside:avoid}.questions{max-width:none}}