:root{--math-blue:#117fea;--math-deep:#082f79;--math-sky:#dff6ff;--math-orange:#ff741b;--math-green:#22bd62}

/* V6.62: current artwork paths used on every viewport. */
.math-page{position:relative;min-height:var(--app-h);max-width:853px;margin:0 auto;overflow-x:hidden;color:var(--math-deep);background:#dff6ff url('assets/reader-backgrounds/bg-math-study-v3.png') center top/100% auto repeat-y;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}
.math-page button{font-family:inherit}.math-nav{position:absolute;z-index:20;left:0;right:0;top:0;height:116px;pointer-events:none}.math-nav-btn{position:absolute;top:max(22px,calc(var(--sat) + 10px));width:68px;height:68px;border:0;border-radius:50%;background:rgba(255,255,255,.96);box-shadow:0 7px 15px rgba(24,82,151,.24);display:grid;place-items:center;pointer-events:auto}.math-nav-btn:first-child{left:max(24px,var(--sal))}.math-nav-btn:last-child{right:max(24px,var(--sar))}.math-nav-btn img{width:39px;height:39px;object-fit:contain}
.math-preview-page{position:relative;min-height:0;background:#dff6ff}.math-preview-image{display:block;width:100%;height:auto}.math-preview-hit{position:absolute;z-index:5;border:0;background:transparent;cursor:pointer}.math-preview-back{left:1%;top:.8%;width:15%;height:7%}.math-preview-home{right:1%;top:.8%;width:15%;height:7%}.math-preview-book{left:7%;right:7%;top:46%;height:40%}.math-preview-unit{width:47%;height:15%}.math-preview-unit.u1{left:2%;top:23%}.math-preview-unit.u2{right:2%;top:23%}.math-preview-unit.u3{left:2%;top:39%}.math-preview-unit.u4{right:2%;top:39%}.math-preview-unit.u5{left:2%;top:55%}.math-preview-unit.u6{right:2%;top:55%}.math-preview-unit.u7{left:2%;top:71%}.math-preview-unit.u8{right:2%;top:71%}.math-preview-fun{left:2%;right:2%;top:86%;height:11%}
@media(orientation:portrait){.math-preview-page{background:#a9c4a4}.math-preview-page::after{content:'';position:absolute;left:0;right:0;bottom:0;height:5%;background:linear-gradient(to bottom,rgba(169,196,164,0),#a9c4a4);pointer-events:none;z-index:4}}
#app:has(.math-preview-page){background:#a9c4a4}body:has(.math-preview-page){background:#a9c4a4}
.math-practice-entry{position:absolute;z-index:8;left:6%;right:6%;bottom:2.4%;min-height:92px;border:2px solid rgba(255,255,255,.95);border-radius:25px;padding:12px 18px;display:grid;grid-template-columns:62px 1fr 38px;gap:14px;align-items:center;background:linear-gradient(145deg,rgba(255,255,255,.98),rgba(255,243,216,.98));box-shadow:0 13px 30px rgba(43,99,139,.22);text-align:left;color:#0c417b}.math-practice-entry-icon{width:60px;height:60px;border-radius:18px;background:linear-gradient(145deg,#fff1d5,#ffd897);display:grid;place-items:center}.math-practice-entry-icon img{width:47px;height:47px;object-fit:contain}.math-practice-entry-copy{min-width:0;display:grid;grid-template-columns:auto 1fr;align-items:baseline;column-gap:10px}.math-practice-entry-copy small{grid-column:1/-1;color:#d67a23;font-size:13px;font-style:normal;font-weight:900}.math-practice-entry-copy strong{font-size:25px;line-height:1.25}.math-practice-entry-copy em{color:#66819b;font-size:14px;font-style:normal;font-weight:800}.math-practice-entry-arrow{width:36px;height:36px;object-fit:contain}.math-practice-entry:active{transform:scale(.985)}
@media(max-width:430px){.math-practice-entry{left:4%;right:4%;bottom:2%;min-height:82px;padding:9px 13px;grid-template-columns:54px 1fr 32px;gap:10px;border-radius:22px}.math-practice-entry-icon{width:52px;height:52px;border-radius:16px}.math-practice-entry-icon img{width:41px;height:41px}.math-practice-entry-copy strong{font-size:22px}.math-practice-entry-arrow{width:31px;height:31px}}
.math-book-page{background-image:url('assets/math/07_previews/preview_01_book_select_v547.png')}.math-book-hero{position:relative;height:685px;padding-top:90px}.math-world-logo{display:block;width:70%;max-height:230px;object-fit:contain;margin:0 auto;filter:drop-shadow(0 9px 4px rgba(0,72,172,.13))}.math-book-jimmy{position:absolute;width:44%;height:390px;object-fit:contain;left:8%;bottom:10px}.math-book-slogan{position:absolute;right:6%;bottom:225px;width:43%;padding:13px 18px;border-radius:999px;background:rgba(255,255,255,.92);color:#0b4390;text-align:center;font-size:20px;line-height:1.35;font-weight:900;box-shadow:0 8px 18px rgba(42,108,174,.14)}
.math-sheet{position:relative;margin-top:-36px;padding:34px 25px 155px;border-radius:50px 50px 0 0;background:rgba(255,253,248,.98);box-shadow:0 -10px 28px rgba(71,113,148,.16)}.math-sheet-title{margin:0 0 26px;text-align:center;font-size:30px;line-height:1.25;color:#0b3575}.math-book-card{position:relative;width:100%;min-height:650px;border:0;border-radius:42px;background:rgba(255,255,255,.96);box-shadow:inset 0 0 0 1px #edf1f4,0 14px 30px rgba(39,82,118,.14);display:grid;place-items:center;padding:40px 88px 40px 38px}.math-book-cover{width:92%;max-height:570px;object-fit:contain;filter:drop-shadow(0 14px 12px rgba(25,72,108,.20))}.math-round-go{position:absolute;right:28px;top:50%;transform:translateY(-50%);width:74px;height:74px;border-radius:50%;background:linear-gradient(145deg,#42b8ff,#0878ed);box-shadow:0 7px 12px rgba(5,110,219,.27);display:grid;place-items:center}.math-round-go img{width:35px;height:35px}
.math-units-page{background-image:url('assets/math/07_previews/preview_02_unit_directory.png')}.math-units-head{position:relative;height:390px;padding-top:110px;text-align:center}.math-units-jimmy{position:absolute;left:2%;bottom:-12px;width:34%;height:300px;object-fit:contain}.math-units-logo{position:relative;width:54%;margin:0 auto;background:rgba(255,255,255,.92);border-radius:46% 54% 45% 55%;padding:22px 28px;box-shadow:0 8px 18px rgba(53,103,158,.18)}.math-units-logo b{display:block;font-size:37px;color:#0d3a82}.math-units-logo span{display:inline-block;margin-top:8px;padding:6px 21px;border-radius:999px;background:#cbecff;color:#1768bd;font-size:20px;font-weight:900}
.math-unit-grid{position:relative;margin-top:-8px;padding:26px 22px 160px;display:grid;grid-template-columns:1fr 1fr;gap:18px;background:rgba(250,253,255,.94);border-radius:48px 48px 0 0}.math-unit-card{position:relative;min-height:258px;border:1px solid rgba(255,255,255,.88);border-radius:28px;overflow:hidden;padding:21px 18px;text-align:left;box-shadow:0 9px 18px rgba(40,85,132,.15)}.math-unit-card:nth-child(4n+1),.math-unit-card:nth-child(4n){background:linear-gradient(145deg,#dcfff5,#ebfffc)}.math-unit-card:nth-child(4n+2){background:linear-gradient(145deg,#e3f6ff,#eef9ff)}.math-unit-card:nth-child(4n+3){background:linear-gradient(145deg,#fff0e7,#fff8f2)}.math-unit-num{position:absolute;z-index:2;left:16px;top:16px;width:60px;height:60px;border-radius:50%;display:grid;place-items:center;background:linear-gradient(145deg,#37cfa8,#079d7c);color:white;font-size:31px;font-weight:950;box-shadow:0 5px 10px rgba(0,137,112,.23)}.math-unit-card:nth-child(4n+2) .math-unit-num{background:linear-gradient(145deg,#4eb7ff,#0677e7)}.math-unit-card:nth-child(4n+3) .math-unit-num{background:linear-gradient(145deg,#ff9a47,#ff5119)}.math-unit-card h3{position:relative;z-index:2;margin:4px 0 0 74px;min-height:64px;font-size:22px;line-height:1.25;color:#0a367a}.math-unit-art{position:absolute;left:6px;right:6px;bottom:0;width:calc(100% - 12px);height:165px;object-fit:cover;object-position:center;border-radius:22px;opacity:.98}.math-unit-go{position:absolute;z-index:3;right:15px;bottom:15px;width:48px;height:48px;border-radius:50%;background:#16a66f;display:grid;place-items:center;box-shadow:0 4px 9px rgba(12,111,80,.22)}.math-unit-go img{width:24px;height:24px}
.math-lesson-page{background-image:url('assets/reader-backgrounds/bg-math-study-v3.png')}.math-lesson-hero{position:relative;height:590px;overflow:hidden;background:#68c9ff}.math-lesson-hero>img{width:100%;height:100%;object-fit:cover}.math-lesson-shade{position:absolute;inset:0;background:linear-gradient(180deg,rgba(20,125,219,.05),rgba(255,255,255,0) 60%,rgba(234,249,255,.75))}.math-unit-pill{position:absolute;top:105px;left:50%;transform:translateX(-50%);padding:10px 30px;border-radius:18px;background:linear-gradient(#ff9d38,#ff6718);color:#fff;font-size:25px;font-weight:950;box-shadow:0 8px 15px rgba(181,75,10,.23)}.math-lesson-title{position:absolute;top:160px;left:10%;right:10%;margin:0;text-align:center;color:white;font-size:42px;line-height:1.15;font-weight:950;text-shadow:0 4px 0 #064cbd,0 6px 12px rgba(0,41,117,.4)}
.math-lesson-list{position:relative;margin-top:-38px;padding:32px 21px 130px;border-radius:46px 46px 0 0;background:#e2f7ff}.math-lesson-card{position:relative;width:100%;min-height:156px;margin-bottom:16px;border:0;border-radius:35px;background:rgba(255,255,255,.97);box-shadow:0 9px 18px rgba(37,100,148,.14);padding:26px 205px 23px 118px;text-align:left;overflow:hidden}.math-lesson-index{position:absolute;left:24px;top:50%;transform:translateY(-50%);width:72px;height:72px;border-radius:24px;background:linear-gradient(145deg,#54bfff,#087af0);color:#fff;display:grid;place-items:center;font-size:33px;font-weight:950}.math-lesson-card:nth-child(even) .math-lesson-index{background:linear-gradient(145deg,#ff9d45,#ff5c20)}.math-lesson-card h3{margin:0;font-size:27px;line-height:1.3;color:#07367d}.math-lesson-card p{margin:8px 0 0;font-size:17px;color:#647795}.math-lesson-card .math-card-art{position:absolute;right:0;top:0;width:190px;height:100%;object-fit:cover;opacity:.88}.math-lesson-card .math-card-go{position:absolute;right:22px;top:50%;transform:translateY(-50%);width:54px;height:54px;border-radius:50%;background:rgba(255,255,255,.94);display:grid;place-items:center;box-shadow:0 5px 12px rgba(39,87,130,.16)}.math-card-go img{width:27px;height:27px}
.math-study-page{background-image:url('assets/reader-backgrounds/bg-math-study-v3.png')}.math-study-hero{position:relative;height:430px;padding-top:78px;overflow:hidden}.math-study-logo{display:block;width:58%;height:175px;object-fit:contain;margin:0 auto}.math-study-jimmy{position:absolute;right:3%;bottom:0;width:34%;height:255px;object-fit:contain}.math-study-hero p{position:absolute;left:24%;bottom:43px;margin:0;padding:8px 20px;border-radius:999px;background:rgba(255,248,229,.94);color:#8d4516;font-size:18px;font-weight:900}.math-mode-shell{position:relative;margin-top:-8px;padding-bottom:120px;background:rgba(251,254,255,.97);border-radius:42px 42px 0 0;box-shadow:0 -8px 20px rgba(47,107,152,.14)}.math-tabs{display:grid;grid-template-columns:repeat(3,1fr);padding:0 18px;transform:translateY(-3px)}.math-tab{height:88px;border:1px solid #cfe2ef;background:#f8fcff;color:#174888;display:flex;align-items:center;justify-content:center;gap:9px;font-size:22px;font-weight:950}.math-tab:first-child{border-radius:30px 0 0 30px}.math-tab:last-child{border-radius:0 30px 30px 0}.math-tab img{width:39px;height:39px;object-fit:contain}.math-tab.active{color:#fff;background:linear-gradient(145deg,#ff962f,#ff651a);border-color:#ff7a20;box-shadow:0 7px 14px rgba(255,98,20,.25)}.math-tab[data-mode="video"].active{background:linear-gradient(145deg,#39b8ff,#0783ed);border-color:#1596ed}.math-tab[data-mode="practice"].active{background:linear-gradient(145deg,#6ddd8e,#25bf63);border-color:#32c96a}.math-mode-content{padding:24px 30px 0}
.math-source-chip{display:inline-flex;align-items:center;padding:7px 13px;border-radius:999px;background:#eaf7ff;color:#1672c9;font-size:14px;font-weight:900}.math-activity-title{margin:14px 0 20px;padding:18px 20px;border-radius:25px;background:linear-gradient(135deg,#e8f8ff,#d9f2ff);font-size:30px;line-height:1.3;text-align:center;color:#07367d}.math-concept-image{display:block;width:min(74%,520px);max-height:360px;object-fit:contain;margin:8px auto 20px;filter:drop-shadow(0 9px 12px rgba(34,102,149,.15))}.math-notes{display:grid;gap:14px}.math-note-block{padding:17px 18px;border:1px solid #cde9f7;border-radius:23px;background:rgba(245,252,255,.92);font-size:18px;line-height:1.75;color:#173f75}.math-note-block h3{margin:0 0 8px;color:#077bc5;font-size:21px}.math-note-block p{margin:6px 0}.math-note-block strong{color:#ff631d}.math-empty{min-height:420px;border:2px dashed #b9dff2;border-radius:30px;background:rgba(246,252,255,.8);display:grid;place-items:center;text-align:center;padding:40px 28px}.math-empty img{width:90px;height:90px;object-fit:contain;opacity:.82}.math-empty h3{margin:15px 0 7px;font-size:25px}.math-empty p{margin:0;color:#7087a5;line-height:1.7}
.math-table-wrap{max-width:100%;overflow-x:auto;margin:12px 0;border-radius:16px}.math-source-table{border-collapse:collapse;min-width:560px;width:100%;background:transparent}.math-source-table th,.math-source-table td{border:1px solid #acd5e8;padding:10px 12px;text-align:left;vertical-align:top;white-space:nowrap;background:transparent}.math-source-table th{color:#0874bd;font-weight:950}
.math-video-box{min-height:420px;border:10px solid white;border-radius:34px;background:linear-gradient(160deg,#204d70,#0d2e49);box-shadow:0 10px 22px rgba(21,67,101,.24);display:grid;place-items:center;text-align:center;color:white}.math-video-box img{width:92px;height:92px;opacity:.84}.math-video-box h3{font-size:26px;margin:12px 0 6px}.math-video-box p{margin:0;color:#c8e7f7}.math-video-list{margin-top:22px;display:grid;gap:12px}.math-video-row{width:100%;min-height:100px;border:1px solid #dcebf5;border-radius:22px;background:white;padding:14px 18px;text-align:left;display:grid;grid-template-columns:56px 1fr 36px;gap:13px;align-items:center}.math-video-row b{width:52px;height:52px;border-radius:16px;background:#e7f5ff;display:grid;place-items:center;color:#087be8;font-size:20px}.math-video-row span{font-size:19px;font-weight:900;color:#0a397c}.math-video-row small{font-size:14px;color:#8091a7}.math-video-row img{width:30px;height:30px;opacity:.55}
.math-practice-meta{display:flex;justify-content:space-between;gap:12px;align-items:center}.math-qcount,.math-qname{padding:10px 17px;border-radius:999px;background:#fff3df;font-size:17px;font-weight:900}.math-qname{background:#e5f5ff}.math-question{margin:20px 0;padding:25px 24px;border-radius:28px;background:white;box-shadow:0 8px 20px rgba(39,87,130,.12);font-size:27px;line-height:1.5;font-weight:900;color:#092f70}.math-options{display:grid;gap:14px}.math-option{position:relative;width:100%;min-height:84px;border:2px solid #d7e5ef;border-radius:25px;background:#f8fbff;text-align:left;padding:16px 18px 16px 84px;color:#0b3476;font-size:23px;font-weight:900}.math-option b{position:absolute;left:19px;top:50%;transform:translateY(-50%);width:50px;height:50px;border-radius:50%;background:#dfedf9;display:grid;place-items:center}.math-option.correct{border-color:#23c65d;background:#eafff0}.math-option.correct b{background:#27c95e;color:white}.math-option.wrong{border-color:#ff505b;background:#fff0f1}.math-option.wrong b{background:#ff505b;color:white}.math-answer-icon{position:absolute;right:17px;top:50%;transform:translateY(-50%);width:42px;height:42px;object-fit:contain}.math-thinking{display:none;margin-top:18px;padding:18px 20px;border:2px solid #b9e5f8;border-radius:25px;background:#eaf8ff;font-size:17px;line-height:1.7}.math-thinking.show{display:block}.math-thinking h3{margin:0 0 5px;font-size:21px}.math-thinking img{float:left;width:48px;height:48px;margin:2px 12px 8px 0}.math-practice-nav{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:24px}.math-practice-nav button{height:64px;border:1px solid #b8d7ef;border-radius:24px;background:white;color:#10509b;font-size:20px;font-weight:900}.math-practice-nav button:last-child{background:linear-gradient(145deg,#39b8ff,#087ded);color:white;border-color:#0782ed}
@media(max-width:560px){.math-nav{height:90px}.math-nav-btn{width:52px;height:52px;top:max(12px,calc(var(--sat) + 6px))}.math-nav-btn:first-child{left:16px}.math-nav-btn:last-child{right:16px}.math-nav-btn img{width:29px;height:29px}.math-book-hero{height:500px;padding-top:70px}.math-world-logo{width:74%;height:165px}.math-book-jimmy{height:300px;width:46%}.math-book-slogan{right:4%;bottom:170px;font-size:15px;padding:10px 11px}.math-sheet{margin-top:-24px;padding:27px 14px 100px;border-radius:34px 34px 0 0}.math-sheet-title{font-size:23px;margin-bottom:20px}.math-book-card{min-height:500px;border-radius:30px;padding:25px 65px 25px 20px}.math-round-go{width:57px;height:57px;right:13px}.math-round-go img{width:28px;height:28px}.math-units-head{height:285px;padding-top:82px}.math-units-jimmy{height:220px}.math-units-logo{width:62%;padding:17px}.math-units-logo b{font-size:25px}.math-units-logo span{font-size:15px}.math-unit-grid{gap:11px;padding:18px 11px 90px;border-radius:32px 32px 0 0}.math-unit-card{min-height:202px;border-radius:22px;padding:13px 11px}.math-unit-num{width:45px;height:45px;font-size:24px;left:10px;top:10px}.math-unit-card h3{margin-left:53px;font-size:16px;min-height:56px}.math-unit-art{height:132px}.math-unit-go{width:39px;height:39px;right:10px;bottom:10px}.math-unit-go img{width:20px;height:20px}.math-lesson-hero{height:405px}.math-unit-pill{top:78px;font-size:18px;padding:8px 21px}.math-lesson-title{top:127px;font-size:29px}.math-lesson-list{padding:24px 11px 90px;border-radius:32px 32px 0 0}.math-lesson-card{min-height:120px;margin-bottom:12px;border-radius:26px;padding:20px 130px 18px 82px}.math-lesson-index{left:16px;width:52px;height:52px;border-radius:17px;font-size:24px}.math-lesson-card h3{font-size:19px}.math-lesson-card p{font-size:13px}.math-lesson-card .math-card-art{width:125px}.math-lesson-card .math-card-go{right:13px;width:42px;height:42px}.math-study-hero{height:290px;padding-top:56px}.math-study-logo{width:60%;height:120px}.math-study-jimmy{height:190px}.math-study-hero p{left:20%;bottom:28px;font-size:13px}.math-mode-shell{border-radius:30px 30px 0 0}.math-tabs{padding:0 8px}.math-tab{height:66px;font-size:16px;gap:5px}.math-tab:first-child{border-radius:22px 0 0 22px}.math-tab:last-child{border-radius:0 22px 22px 0}.math-tab img{width:28px;height:28px}.math-mode-content{padding:18px 13px 0}.math-activity-title{font-size:23px}.math-concept-image{width:88%;max-height:270px}.math-note-block{font-size:16px;line-height:1.7}.math-note-block h3{font-size:18px}.math-video-box{min-height:290px}.math-video-row{grid-template-columns:46px 1fr 28px}.math-video-row b{width:44px;height:44px}.math-video-row span{font-size:16px}.math-question{font-size:21px}.math-option{font-size:18px;min-height:72px;padding-left:71px}.math-option b{width:43px;height:43px}.math-answer-icon{width:35px;height:35px}.math-practice-meta{font-size:14px}.math-qcount,.math-qname{font-size:14px;padding:8px 11px}}
@media(min-width:700px) and (orientation:landscape){.math-page{max-width:1180px}.math-unit-grid{grid-template-columns:repeat(4,1fr)}.math-unit-card{min-height:240px}.math-lesson-list{display:grid;grid-template-columns:1fr 1fr;gap:16px}.math-lesson-card{margin:0}.math-mode-content{max-width:980px;margin:0 auto}.math-study-hero{height:360px}.math-book-card{min-height:540px}.math-book-cover{max-height:480px}}

/* V5.30：小单元卡片与学习页移除重复插图，探索区暂时完全留白。 */
.math-lesson-card{padding-right:92px}
.math-study-heading{min-height:230px;padding:108px 90px 40px;text-align:center}
.math-study-heading span{display:inline-block;padding:7px 19px;border-radius:999px;background:#fff1d8;color:#e86116;font-weight:900}
.math-study-heading h1{margin:15px auto 0;max-width:620px;font-size:34px;line-height:1.35;color:#07367d}
.math-study-heading+.math-mode-shell{margin-top:0}
.math-explore-blank{min-height:430px}
.math-option{padding-right:66px}
.math-option-badge{position:absolute;left:16px;top:50%;transform:translateY(-50%);width:54px;height:54px;object-fit:contain}
@media(max-width:560px){.math-lesson-card{padding-right:66px}.math-study-heading{min-height:180px;padding:82px 58px 28px}.math-study-heading h1{font-size:24px}.math-option-badge{left:13px;width:46px;height:46px}}

/* V5.32：探索学习采用原生文字卡片，不再裁剪知识清单截图。 */
.math-knowledge-card{padding:25px;border:2px solid #cde8f6;border-radius:28px;background:linear-gradient(150deg,#f8fdff,#edf9ff);box-shadow:0 10px 24px rgba(35,91,132,.12)}
.math-knowledge-head{display:flex;align-items:flex-start;justify-content:space-between;gap:16px;margin-bottom:16px}
.math-knowledge-head h2{margin:9px 0 0;font-size:27px;line-height:1.35;color:#07367d}
.math-knowledge-head>b{flex:none;padding:9px 14px;border-radius:999px;background:#edf7ff;color:#1978c9;font-size:16px}
.math-knowledge-lead{margin:0 0 18px;padding:14px 17px;border-left:5px solid #2b93ef;border-radius:0 14px 14px 0;background:#e5f4ff;color:#234d78;font-size:18px;line-height:1.75}
.math-knowledge-points{list-style:none;margin:0 0 18px;padding:0;display:grid;gap:11px}.math-knowledge-points li{display:flex;align-items:flex-start;gap:11px;color:#244c72;font-size:18px;line-height:1.7}.math-knowledge-points li>b{flex:none;width:27px;height:27px;margin-top:2px;border-radius:9px;background:#1188ed;color:#fff;display:grid;place-items:center;font-size:14px}.math-knowledge-points li span{min-width:0;overflow-wrap:anywhere}
.math-knowledge-block{margin-top:15px;padding:17px 18px;border-radius:18px;border:1px solid transparent}.math-knowledge-block h3{display:inline-block;margin:0 0 9px;padding:4px 12px;border-radius:999px;font-size:16px}.math-knowledge-block p,.math-knowledge-block div,.math-knowledge-block ol{margin:0;color:#304d70;font-size:18px;line-height:1.75;overflow-wrap:anywhere}.math-knowledge-block ol{padding-left:24px}.math-knowledge-block.formula{background:#fff5e5;border-color:#ffddab}.math-knowledge-block.formula h3{background:#ff9c39;color:#fff}.math-knowledge-block.formula div{color:#a54d0b;font-weight:900;white-space:pre-wrap}.math-knowledge-block.method{background:#eafaf1;border-color:#bae9ce}.math-knowledge-block.method h3{background:#28af69;color:#fff}.math-knowledge-block.example{background:#f4efff;border-color:#d8c8fa}.math-knowledge-block.example h3{background:#8464d8;color:#fff}.math-knowledge-tip{margin-top:15px;padding:15px 17px;border-radius:18px;background:#fff0ef;border:1px solid #ffc9c3;color:#8f3d37}.math-knowledge-tip strong{color:#ed644f}.math-knowledge-tip p{margin:6px 0 0;font-size:17px;line-height:1.7}
.math-source-card{background:linear-gradient(150deg,#fbfeff,#f1faff)}
.math-source-rich{color:#244c72;font-size:18px;line-height:1.75;overflow-wrap:anywhere}
.math-source-rich p{margin:0 0 14px}
.math-source-rich strong{color:#07367d;font-weight:900}
.math-source-rich u{color:#ec6f3f;text-decoration-color:#ffc45c;text-decoration-thickness:3px;text-underline-offset:4px}
.math-source-rich sup,.math-source-rich sub{font-size:.76em}
.math-source-rich img{display:inline-block;max-width:100%;height:auto;max-height:360px;margin:5px 7px;vertical-align:middle;object-fit:contain}
.math-source-rich p:has(>img:only-child){text-align:center}
.math-source-table-wrap{width:100%;margin:18px 0;overflow-x:auto;border:1px solid #c8deec;border-radius:16px;background:rgba(255,255,255,.72);-webkit-overflow-scrolling:touch}
.math-source-rich table{width:max-content;min-width:100%;border-collapse:collapse;color:#244c72;font-size:16px;line-height:1.55}
.math-source-rich th,.math-source-rich td{min-width:92px;padding:11px 13px;border:1px solid #c8deec;vertical-align:middle;background:transparent}
.math-source-rich tr:first-child td,.math-source-rich th{color:#0d65a8;font-weight:900}
.math-source-rich .math-source-table-wrap p{margin:0}
.math-knowledge-nav{display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:12px;margin-top:20px}
.math-knowledge-nav button{min-height:58px;border:1px solid #c9dfef;border-radius:21px;background:#fff;color:#13589b;font-size:18px;font-weight:900;display:flex;align-items:center;justify-content:center;gap:7px}
.math-knowledge-nav button:last-child{background:linear-gradient(145deg,#39b8ff,#087ded);border-color:#0782ed;color:#fff}
.math-knowledge-nav button:disabled{opacity:.32}
.math-knowledge-nav img{width:27px;height:27px;object-fit:contain}
.math-knowledge-nav span{text-align:center;color:#7187a3;font-weight:800;white-space:nowrap}
@media(max-width:560px){.math-knowledge-card{padding:19px 16px;border-radius:22px}.math-knowledge-head h2{font-size:22px}.math-knowledge-head>b{font-size:14px;padding:7px 10px}.math-knowledge-lead,.math-knowledge-points li,.math-knowledge-block p,.math-knowledge-block div,.math-knowledge-block ol,.math-source-rich{font-size:16px}.math-source-rich img{max-height:280px;margin:4px}.math-source-rich table{font-size:15px}.math-source-rich th,.math-source-rich td{padding:9px 11px}.math-knowledge-nav{grid-template-columns:1fr 1fr}.math-knowledge-nav span{grid-column:1/-1;grid-row:1}.math-knowledge-nav button{font-size:16px;min-height:52px}}

/* V5.35：数学世界改为知识汇总与八单元练习。 */
.math-hub-page,.math-practice-units,.math-test-page{background:linear-gradient(180deg,#73c9ff,#e8f8ff 360px,#f7fbff)}
.math-hub-hero{min-height:320px;padding:86px 20px 44px;text-align:center;background:url('assets/math/07_previews/preview_01_book_select_v547.png') center/cover no-repeat}.math-hub-hero img{width:min(72%,430px);height:auto}.math-hub-hero p{margin:8px 0 0;color:#fff;font-size:21px;font-weight:950;text-shadow:0 2px 5px rgba(23,89,143,.25)}
.math-hub-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;width:min(calc(100% - 30px),940px);margin:-24px auto 0;padding-bottom:50px}.math-hub-card{position:relative;min-height:210px;border:2px solid rgba(255,255,255,.9);border-radius:30px;padding:26px 68px 26px 28px;background:#fff;text-align:left;box-shadow:0 15px 36px rgba(31,92,139,.16);overflow:hidden}.math-hub-card.knowledge{background:linear-gradient(145deg,#fff,#e9f6ff)}.math-hub-card.practice{background:linear-gradient(145deg,#fff,#fff2dc)}.math-hub-icon{display:grid;place-items:center;width:62px;height:62px;margin-bottom:15px;border-radius:20px;background:#e3f3ff;font-size:34px}.math-hub-card.practice .math-hub-icon{background:#ffedcd}.math-hub-card small{color:#3287bd;font-size:14px;font-weight:950}.math-hub-card h2{margin:5px 0 8px;color:#0e3f78;font-size:28px}.math-hub-card p{margin:0;color:#69819b;font-size:15px;line-height:1.55}.math-hub-card>img{position:absolute;right:22px;top:50%;width:38px;height:38px;transform:translateY(-50%);object-fit:contain}
.math-practice-hero{padding:96px 20px 45px;text-align:center;color:#0a407c}.math-practice-hero>span{display:inline-block;padding:7px 18px;border-radius:999px;background:#fff0cf;color:#e07424;font-weight:950}.math-practice-hero h1{margin:13px 0 5px;font-size:36px}.math-practice-hero p{margin:0;color:#547391;font-weight:800}.math-practice-unit-grid{display:grid;grid-template-columns:1fr 1fr;gap:15px;width:min(calc(100% - 28px),900px);margin:0 auto;padding-bottom:50px}.math-practice-unit-card{position:relative;display:grid;grid-template-columns:58px 1fr 34px;align-items:center;gap:14px;min-height:125px;border:1px solid #d9eaf5;border-radius:25px;padding:17px;background:#fff;text-align:left;box-shadow:0 8px 22px rgba(30,91,140,.1)}.math-practice-unit-card>b{display:grid;place-items:center;width:55px;height:55px;border-radius:18px;background:linear-gradient(145deg,#33adfb,#117de7);color:#fff;font-size:25px}.math-practice-unit-card small{color:#5f8caf;font-weight:900}.math-practice-unit-card h2{margin:4px 0 5px;color:#143e74;font-size:18px;line-height:1.35}.math-practice-unit-card p{margin:0;color:#7d91a7;font-size:13px}.math-practice-unit-card>img{width:32px;height:32px;object-fit:contain}
.math-test-head{display:flex;align-items:center;justify-content:space-between;gap:20px;min-height:220px;padding:90px max(22px,calc((100% - 900px)/2)) 36px;background:linear-gradient(150deg,#dff5ff,#fff5df)}.math-test-head small{color:#e47728;font-size:15px;font-weight:950}.math-test-head h1{margin:7px 0 0;color:#0c4079;font-size:29px;line-height:1.35}.math-test-head>strong{flex:none;padding:9px 15px;border-radius:999px;background:#fff;color:#217bb8;font-size:16px;box-shadow:0 4px 12px rgba(24,97,150,.1)}
.math-test-shell{width:min(calc(100% - 24px),900px);margin:-18px auto 0;padding:20px 20px 45px;border-radius:30px 30px 0 0;background:#fff;box-shadow:0 -5px 25px rgba(32,94,142,.08)}.math-test-meta{display:flex;align-items:center;gap:11px;margin-bottom:16px}.math-test-meta span{flex:none;padding:6px 13px;border-radius:999px;background:#1688f8;color:#fff;font-weight:950}.math-test-meta b{color:#174774;font-size:18px;line-height:1.45}
.math-source-question{padding:20px;border:1px solid #dceaf3;border-radius:22px;background:#fbfdff;color:#263f5b;font-size:17px;line-height:1.75;overflow-wrap:anywhere}.math-source-question p{margin:0 0 12px;white-space:pre-wrap}.math-source-question .practice-source-heading{display:none}.math-source-question img{display:block;max-width:100%;max-height:520px;margin:12px auto;object-fit:contain}.practice-table-wrap{max-width:100%;margin:14px 0;overflow-x:auto;border-radius:14px;-webkit-overflow-scrolling:touch}.practice-table-wrap table{width:max-content;min-width:100%;border-collapse:collapse;background:#fff}.practice-table-wrap td{min-width:100px;padding:9px 11px;border:1px solid #cadde9;vertical-align:middle}
.math-work-area{display:grid;grid-template-columns:1fr auto;gap:10px;margin-top:16px;padding:17px;border-radius:21px;background:#fff7e7;border:1px solid #ffe0a4}.math-work-area label{grid-column:1/-1;color:#9d5d18;font-weight:950}.math-work-area textarea{min-height:80px;resize:vertical;border:1px solid #e8c78f;border-radius:15px;padding:12px;background:#fff;font:inherit;color:#31475d}.math-work-area button{align-self:end;min-height:48px;border:0;border-radius:15px;padding:0 16px;background:#ee8a28;color:#fff;font-weight:950}.math-work-area button.done{background:#2fae65}.math-test-shell .math-practice-nav button:disabled{opacity:.32}
@media(max-width:700px){.math-hub-grid,.math-practice-unit-grid{grid-template-columns:1fr}.math-hub-hero{min-height:270px;padding-top:82px}.math-hub-card{min-height:180px}.math-practice-hero{padding-top:86px}.math-practice-hero h1{font-size:29px}.math-test-head{min-height:190px;padding:80px 65px 32px 20px}.math-test-head h1{font-size:22px}.math-test-head>strong{font-size:14px}.math-test-shell{padding:17px 13px 35px}.math-source-question{padding:16px 13px;font-size:16px}.math-work-area{grid-template-columns:1fr}.math-work-area button{min-height:48px}}

/* V5.38：一页一题，完成后翻面显示教师版答案。 */
.practice-flip-shell{perspective:1500px}.practice-flip-card{position:relative;width:100%;min-height:360px;transform-style:preserve-3d;transition:transform .58s cubic-bezier(.2,.72,.23,1),height .28s ease}.practice-flip-card.is-flipped{transform:rotateY(180deg)}
.practice-face{position:absolute;inset:0;overflow:auto;padding:20px;border:1px solid #d9e8f2;border-radius:27px;background:linear-gradient(155deg,#fff,#f7fbff);box-shadow:0 12px 30px rgba(26,77,119,.12);backface-visibility:hidden;-webkit-backface-visibility:hidden}.practice-back{transform:rotateY(180deg);background:linear-gradient(155deg,#fffdf8,#fff6e7);border-color:#f2d8aa}.practice-face-label{display:inline-flex;margin-bottom:15px;padding:7px 15px;border-radius:999px;background:#e6f4ff;color:#1476cc;font-size:15px;font-weight:950}.practice-face-label.answer{background:#ffebc8;color:#c56b1f}
.practice-complete-btn{display:block;width:min(100%,360px);height:62px;margin:22px auto 0;border:0;border-radius:21px;background:linear-gradient(145deg,#33c977,#16a85b);box-shadow:0 8px 18px rgba(17,151,79,.24);color:#fff;font-size:21px;font-weight:950}.practice-complete-btn:active{transform:scale(.985)}
.practice-answer-content{padding:18px;border-radius:20px;background:rgba(255,255,255,.82);color:#3c4c5c;font-size:17px;line-height:1.78;white-space:normal;overflow-wrap:anywhere}.practice-answer-content .practice-label{display:inline-block;margin:8px 7px 4px 0;padding:3px 9px;border-radius:999px;background:#ffead0;color:#c56515}.practice-media{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(220px,100%),1fr));gap:12px;margin-top:16px}.practice-media img{display:block;width:100%;max-height:440px;margin:0 auto;border-radius:12px;object-fit:contain;background:#fff}.question-media img{border:1px solid #e2eaf0}.answer-media img{border:1px solid #f0d4a7}
@media(max-width:700px){.practice-face{padding:14px;border-radius:22px}.practice-answer-content{padding:14px;font-size:16px}.practice-complete-btn{height:56px;font-size:19px}.practice-media{grid-template-columns:1fr}}
@media(prefers-reduced-motion:reduce){.practice-flip-card{transition:none}}

/* V5.47：课本、口算、专项三入口；专项卡片内直接选择单元。 */
.math-preview-page .math-preview-book{left:7%;right:7%;top:48%;height:14.2%}
.math-preview-page .math-preview-oral{left:7%;right:7%;top:63.4%;height:13.4%}
.math-preview-page .math-preview-special{right:6%;top:77.6%;width:21%;height:13.8%}
.math-entry-unit-select{position:absolute;z-index:9;left:42.5%;top:84.7%;width:30%;height:3.7%;min-height:36px;padding:3px 28px 3px 10px;border:1.5px solid #8acdf5;border-radius:999px;background:rgba(246,252,255,.97);box-shadow:0 4px 10px rgba(31,104,160,.12);color:#1765a8;font-family:inherit;font-size:clamp(12px,2.2vw,18px);font-weight:900}
@media(min-width:700px) and (orientation:landscape){.math-preview-page{width:var(--app-w);height:var(--app-h);min-height:0;max-width:none;margin:0}.math-preview-page .math-preview-image{width:100%;height:100%;object-fit:cover}.math-preview-page .math-preview-back{left:1.5%;top:2%;width:9%;height:12%}.math-preview-page .math-preview-home{right:1.5%;top:2%;width:9%;height:12%}.math-preview-page .math-preview-book{left:52%;right:5%;top:24%;height:19%}.math-preview-page .math-preview-oral{left:52%;right:5%;top:46%;height:19%}.math-preview-page .math-preview-special{left:52%;right:5%;top:68%;width:auto;height:19%}.math-preview-units .math-preview-unit{width:21%;height:25%}.math-preview-units .math-preview-unit.u1{left:5%;top:27%}.math-preview-units .math-preview-unit.u2{left:28%;right:auto;top:27%}.math-preview-units .math-preview-unit.u3{left:51%;top:27%}.math-preview-units .math-preview-unit.u4{left:74%;right:auto;top:27%}.math-preview-units .math-preview-unit.u5{left:5%;top:56%}.math-preview-units .math-preview-unit.u6{left:28%;right:auto;top:56%}.math-preview-units .math-preview-unit.u7{left:51%;top:56%}.math-preview-units .math-preview-unit.u8{left:74%;right:auto;top:56%}}
html.device-landscape .math-preview-page{width:var(--app-w);height:var(--app-h);min-height:0;max-width:none;margin:0}html.device-landscape .math-preview-page .math-preview-image{width:100%;height:100%;object-fit:cover}html.device-landscape .math-preview-page .math-preview-back{left:1.5%;top:2%;width:9%;height:12%}html.device-landscape .math-preview-page .math-preview-home{right:1.5%;top:2%;width:9%;height:12%}html.device-landscape .math-preview-page .math-preview-book{left:52%;right:5%;top:24%;height:19%}html.device-landscape .math-preview-page .math-preview-oral{left:52%;right:5%;top:46%;height:19%}html.device-landscape .math-preview-page .math-preview-special{left:52%;right:5%;top:68%;width:auto;height:19%}html.device-landscape .math-preview-units .math-preview-unit{width:23.4%;height:25.5%}html.device-landscape .math-preview-units .math-preview-unit.u1{left:1.6%;top:39.2%}html.device-landscape .math-preview-units .math-preview-unit.u2{left:26.4%;right:auto;top:39.2%}html.device-landscape .math-preview-units .math-preview-unit.u3{left:50.5%;top:39.2%}html.device-landscape .math-preview-units .math-preview-unit.u4{left:75%;right:auto;top:39.2%}html.device-landscape .math-preview-units .math-preview-unit.u5{left:1.6%;top:66.3%}html.device-landscape .math-preview-units .math-preview-unit.u6{left:26.4%;right:auto;top:66.3%}html.device-landscape .math-preview-units .math-preview-unit.u7{left:50.5%;top:66.3%}html.device-landscape .math-preview-units .math-preview-unit.u8{left:75%;right:auto;top:66.3%}

/* V6.62: current artwork paths used on every viewport. */
.math-page,.math-lesson-page,.math-study-page{background-image:url('assets/reader-backgrounds/bg-math-study-v3.png')}
.math-book-page,.math-hub-hero{background-image:url('assets/math/07_previews/preview_01_book_select_v547.png')}
.math-units-page{background-image:url('assets/math/07_previews/preview_02_unit_directory.png')}