:root{--navy:#071c35;--blue:#377ee8;--teal:#149b8a;--orange:#e8882c;--ink:#16324b;--muted:#64798e}*{box-sizing:border-box}body{margin:0;font-family:"Microsoft YaHei",Arial,sans-serif;background:#edf3fa;color:var(--ink)}button{font:inherit;cursor:pointer;border:0;border-radius:10px;padding:10px 15px;background:var(--blue);color:#fff;font-weight:700}button.alt{background:#eaf1f8;color:var(--ink)}.app{min-height:100vh}.hero,.top{background:var(--navy);color:#fff}.hero{min-height:100vh;padding:7vh max(6vw,28px);display:grid;place-items:center}.hero-in{max-width:1020px}.eyebrow{color:#87baff;letter-spacing:2px}.hero h1{font-size:clamp(30px,4.3vw,52px);line-height:1.18;margin:18px 0 10px}.hero p{font-size:19px;line-height:1.8;max-width:760px;color:#d4e6f8}.facts{display:flex;gap:14px;flex-wrap:wrap;margin:30px 0}.fact{background:#173959;border:1px solid #31587d;border-radius:14px;padding:16px;min-width:145px}.fact b{display:block;font-size:24px;color:#a9d8ff}.shell{max-width:1380px;margin:auto;padding:22px}.top{padding:16px 0}.top .shell,.learn-head{display:flex;justify-content:space-between;gap:15px;align-items:center;flex-wrap:wrap}.tabs,.learn-tabs{display:flex;gap:10px;flex-wrap:wrap}.cat{flex:1;text-align:left;background:#fff;color:var(--ink);border:2px solid transparent;padding:17px;transition:border-color .2s,box-shadow .2s,transform .2s}.cat.active{border-color:var(--blue);box-shadow:0 6px 20px #377ee833}.cat:hover{border-color:#a9c9f5;box-shadow:0 6px 16px #377ee822;transform:translateY(-2px)}.cat small{display:block;color:var(--muted);margin-top:7px}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:16px;margin-top:20px}.card{background:#fff;border-radius:15px;padding:15px;box-shadow:0 6px 22px #17324b12}.device-art{height:130px;border-radius:12px;background:linear-gradient(135deg,#eff6ff,#dbeafd);display:grid;place-items:center;font-size:54px}.card h3{margin:12px 0 8px}.tag,.status{font-size:12px;background:#eaf2fa;padding:5px 8px;border-radius:20px;display:inline-block}.status.done{background:#d8f4e9;color:#087b5c}.card button{margin-top:12px;width:100%}.learn-tabs button.active{background:var(--teal)}.main-panel{background:#fff;border-radius:18px;padding:22px;margin-top:18px;min-height:560px}.intro{display:grid;grid-template-columns:minmax(280px,.9fr) 1.1fr;gap:28px;align-items:center}.big-art{height:380px;border-radius:20px;background:radial-gradient(circle at 50% 25%,#fff,#d7e9fa);display:grid;place-items:center;font-size:150px;position:relative}.hot{position:absolute;width:30px;height:30px;border-radius:50%;background:var(--orange);color:#fff;padding:0;border:3px solid #fff}.info-line{padding:13px;border-left:4px solid var(--blue);background:#f4f8fc;margin:10px 0}.sort-list{display:grid;gap:10px;max-width:780px}.sort-item{background:#f4f8fc;border:1px solid #dbe6f0;padding:14px;border-radius:10px;cursor:grab;display:flex;gap:10px;align-items:center}.sort-item:before{content:"↕";font-size:20px;color:var(--blue)}.choices{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:18px;margin:18px 0;max-width:820px;margin-left:auto;margin-right:auto}.choice{background:#f4f8fc;color:var(--ink);border:2px solid transparent;min-height:105px;text-align:left}.choice.selected{border-color:var(--blue);background:#e5f0ff}.feedback{margin-top:16px;padding:14px;border-radius:10px;background:#e9f8f0;color:#087b5c}.feedback.bad{background:#fff0f0;color:#a52f2f}.zone{border:2px dashed #a9bdd0;border-radius:12px;padding:17px;min-height:100px}.report{line-height:1.8}.score{font-size:30px;color:var(--blue);font-weight:bold}@media(max-width:700px){.intro{grid-template-columns:1fr}.big-art{height:260px}.main-panel{padding:15px}}
.hero-start-btn{margin-top:20px;min-width:146px;padding:10px 18px;border-radius:10px;font-weight:800;box-shadow:0 8px 24px rgba(3,20,42,.3);background:linear-gradient(135deg,var(--blue),#2a63c2);transition:.2s}.hero-start-btn:hover{transform:translateY(-1px)}
.hero{position:relative}
.cover-back-btn{position:fixed;top:20px;left:20px;padding:8px 4px;border:none;background:transparent;color:rgba(255,255,255,.9);font-size:13px;font-weight:700;border-radius:0;cursor:pointer;font-family:inherit;display:inline-flex;align-items:center;gap:6px;transition:opacity .22s;z-index:10000;-webkit-appearance:none;appearance:none;outline:none;box-shadow:none}
.cover-back-btn:hover{opacity:.7}
#bgmFloatBtn{position:fixed;top:64px;right:20px;z-index:10000;display:flex;align-items:flex-end;gap:3px;background:transparent;border:none;padding:4px 2px 2px;cursor:pointer;transition:opacity .2s}
#bgmFloatBtn:hover{opacity:.75}#bgmFloatBtn.muted{opacity:.4}
.bgm-bar{width:4px;border-radius:3px;background:var(--blue);transform-origin:bottom;animation:bgm-pulse var(--dur,.8s) ease-in-out infinite alternate;filter:drop-shadow(0 0 3px rgba(55,126,232,.6))}
#bgmFloatBtn.muted .bgm-bar{background:#b7c4d4;animation:none;height:3px!important;filter:none}
.bgm-bar:nth-child(1){--dur:.7s;--h:12px}.bgm-bar:nth-child(2){--dur:.5s;--h:20px}.bgm-bar:nth-child(3){--dur:.9s;--h:8px}.bgm-bar:nth-child(4){--dur:.6s;--h:16px}
@keyframes bgm-pulse{from{height:3px}to{height:var(--h,16px)}}
#b1Lightbox{position:fixed;inset:0;z-index:20000;background:rgba(3,12,26,.82);display:none;align-items:center;justify-content:center;cursor:zoom-out}
#b1Lightbox.open{display:flex}
#b1LightboxImg{width:min(80vw,80vh);aspect-ratio:1/1;border-radius:14px;box-shadow:0 20px 60px rgba(0,0,0,.5);background-color:#0f2438;background-repeat:no-repeat;cursor:default}
#b1LightboxClose{position:absolute;top:20px;right:24px;width:40px;height:40px;border-radius:50%;background:rgba(255,255,255,.14);color:#fff;font-size:18px;border:0;padding:0;cursor:pointer;display:grid;place-items:center}
#b1LightboxClose:hover{background:rgba(255,255,255,.26)}
/* 安安老师AI导师：结构/交互完全参照C4的c4Tutor系列，颜色改成B1自己的蓝色主题 */
#b1TutorFab{position:fixed;left:8px;top:64vh;z-index:14500;width:68px;height:68px;border:0;border-radius:50%;background:#fff;box-shadow:0 6px 18px rgba(10,52,96,.28);cursor:grab;touch-action:none;user-select:none;padding:0;display:none;align-items:center;justify-content:center;font-family:inherit;overflow:hidden}
#b1TutorFab:active{cursor:grabbing}
.b1-tutor-fab-avatar{width:100%;height:100%;border-radius:50%;object-fit:cover;object-position:center top;background:transparent;border:0;display:block}
#b1TutorMask{position:fixed;inset:0;z-index:16000;background:transparent;display:none;align-items:flex-end;justify-content:flex-start;padding:70px 24px 18px 150px;pointer-events:none}
#b1TutorMask.open{display:flex}
.b1-tutor-window{--b1tf:13px;width:min(760px,82vw);height:min(520px,78vh);background:transparent;border-radius:18px;box-shadow:0 28px 75px rgba(8,34,62,.48),0 8px 22px rgba(8,34,62,.26);display:flex;overflow:visible;position:relative;left:0;top:0;border:0;pointer-events:auto}
.b1-tutor-close{position:absolute;right:14px;top:12px;z-index:3;width:34px;height:34px;border-radius:50%;border:1px solid #d5e1ee;background:#fff;color:#48627d;font-size:22px;cursor:pointer;display:grid;place-items:center}
.b1-tutor-close:hover{color:#b43d35;border-color:#e7b5b0}
.b1-tutor-clr{position:absolute;right:58px;top:13px;z-index:3;width:32px;height:32px;display:grid;place-items:center;border:1px solid #d5e1ee;border-radius:50%;background:rgba(255,255,255,.9);color:#687f96;padding:0;font:17px/1 inherit;cursor:pointer}
.b1-tutor-clr:hover{color:#b43d35;border-color:#e7b5b0;background:#fff8f7}
.b1-tutor-char{position:absolute;z-index:4;left:-138px;top:-92px;width:286px;height:calc(100% + 92px);background:none;display:block;overflow:visible;pointer-events:none}
.b1-tutor-char img{width:100%;height:100%;object-fit:contain;object-position:center bottom;filter:drop-shadow(0 12px 13px rgba(22,53,82,.28))}
.b1-tutor-chat{width:100%;min-width:0;display:flex;flex-direction:column;background:#fff;border-radius:18px;overflow:hidden}
.b1-tutor-head{height:62px;flex-shrink:0;padding:13px 142px 9px 165px;border-bottom:1px solid #dce6f0;cursor:move;user-select:none;touch-action:none;background:linear-gradient(90deg,#eaf2fc,#fff 45%)}
.b1-tutor-head b{display:block;color:#173f70;font-size:16px}
.b1-tutor-head span{font-size:11px;color:#7890a8;display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
#b1TutorMsgs{flex:1;overflow-y:auto;padding:14px 16px 14px 165px;display:flex;flex-direction:column;gap:9px;background:#f7fafd}
.b1tm{max-width:92%;padding:9px 12px;border-radius:12px;font-family:inherit;font-size:var(--b1tf);line-height:1.7;white-space:pre-wrap}
.b1tm.teacher{align-self:flex-start;background:#fff;border:1px solid #dce6f0;color:#35516d;border-radius:4px 12px 12px 12px}
.b1tm.student{align-self:flex-end;background:#e8f2ff;border:1px solid #c7daf2;color:#173f70;border-radius:12px 4px 12px 12px}
.b1tm.loading{color:#7890a8}
.b1-tutor-inp{flex-shrink:0;margin-left:150px;padding:10px 12px 12px;border-top:1px solid #dce6f0;display:flex;gap:8px;background:#fff}
.b1-tutor-inp textarea{flex:1;resize:none;border:1px solid #c7d6e5;border-radius:10px;padding:9px 11px;font-family:inherit;font-size:var(--b1tf);line-height:1.7;outline:none;max-height:90px}
.b1-tutor-inp textarea:focus{border-color:#377ee8;box-shadow:0 0 0 2px rgba(55,126,232,.1)}
.b1-tutor-send{border:0;border-radius:10px;background:#377ee8;color:#fff;font-weight:700;padding:0 18px;cursor:pointer;font-family:inherit}
.b1-tutor-send:disabled{opacity:.45;cursor:not-allowed}
@media(max-width:700px){#b1TutorMask{padding:60px 8px 10px 76px}.b1-tutor-window{width:calc(100vw - 84px);height:72vh}.b1-tutor-char{left:-70px;top:-62px;width:170px;height:calc(100% + 62px)}.b1-tutor-head{padding-left:105px;padding-right:132px}#b1TutorMsgs{padding-left:105px}.b1-tutor-inp{margin-left:92px}#b1TutorFab{width:60px;height:60px}}
.b1-confirm-mask{position:fixed;inset:0;z-index:22000;display:none;align-items:center;justify-content:center;padding:20px;background:rgba(9,30,52,.4);backdrop-filter:blur(10px)}
.b1-confirm-mask.open{display:flex}
.b1-confirm-card{width:min(460px,92vw);padding:24px 26px 22px;border:1px solid rgba(255,255,255,.82);border-radius:18px;background:linear-gradient(135deg,rgba(250,253,255,.95),rgba(227,242,252,.9));box-shadow:0 22px 65px rgba(8,37,67,.28);backdrop-filter:blur(24px);color:var(--ink);text-align:center}
.b1-confirm-icon{width:42px;height:42px;display:grid;place-items:center;margin:0 auto 9px;border-radius:50%;background:rgba(55,126,232,.13);color:var(--blue);font-size:22px;font-weight:900}
.b1-confirm-card h3{margin:0 0 7px;color:#173f70;font-size:19px}
.b1-confirm-card p{margin:0;color:var(--muted);font-size:12.5px;line-height:1.7}
.b1-confirm-actions{display:grid;gap:8px;margin-top:18px}
.b1-confirm-btn{min-height:42px;padding:9px 14px;border:1px solid rgba(55,126,232,.22);border-radius:10px;background:rgba(255,255,255,.7);color:var(--ink);font-weight:800;cursor:pointer}
.b1-confirm-btn:hover{border-color:var(--blue);background:rgba(235,247,255,.94)}
.b1-confirm-btn.primary{border:0;background:linear-gradient(135deg,var(--blue),#2a63c2);color:#fff}
.b1-confirm-btn.platform{border-color:rgba(20,155,138,.35);color:var(--teal)}
.b1-confirm-btn.danger{border-color:rgba(232,136,44,.35);color:#b5651d}
.b1-confirm-btn.cancel{background:rgba(255,255,255,.35);color:var(--muted)}
.hud{background:linear-gradient(100deg,#050f1f,#1e5aa8,#050f1f,#123a63,#050f1f);background-size:400% 100%;animation:hudGradient 16s ease-in-out infinite;color:#fff;height:52px;display:flex;align-items:center}
@keyframes hudGradient{0%{background-position:0% 50%}50%{background-position:100% 50%}100%{background-position:0% 50%}}
@media(prefers-reduced-motion:reduce){.hud{animation:none}}.hud-inner{width:100%;max-width:1380px;margin:0 auto;padding:0 22px;display:flex;align-items:center;gap:14px}.hud-back{color:rgba(255,255,255,.55);font-size:13px;font-weight:500;cursor:pointer;border:0;background:transparent;padding:0;transition:.2s}.hud-back:hover{color:rgba(255,255,255,.92)}.hud-spacer{flex:1}.hud-breadcrumb{display:flex;align-items:center;gap:7px;flex-shrink:0}.hud-step-label{font-size:13px;font-weight:600;color:#fff}.hud-bc-sep{font-size:13px;color:rgba(255,255,255,.28)}.hud-tag{font-size:13px;font-weight:500;color:rgba(255,255,255,.55)}.hud-report-btn{padding:8px 14px;font-size:12.5px;flex-shrink:0}