.ib-ea-root,.ib-shell{font-family:Arial,Helvetica,sans-serif;color:#111}.ib-toolbar{position:sticky;top:0;z-index:100;background:#fff;border:1px solid #d6dbe1;padding:12px 16px;display:grid;grid-template-columns:1fr auto auto;gap:14px;align-items:center;box-shadow:0 3px 10px rgba(0,0,0,.08)}.ib-toolbar strong{font-size:18px}.ib-toolbar small{display:block;color:#666;margin-top:3px}.ib-time,.ib-score{font-size:22px;font-weight:700}.ib-actions{display:flex;align-items:center;gap:9px;flex-wrap:wrap;justify-content:flex-end}.ib-actions span{font-size:13px;padding:7px 10px;border:1px solid #d8dde3;border-radius:16px;background:#f6f7f8}.ib-actions button,.ib-draw-tools button{border:1px solid #6d7783;background:#fff;border-radius:7px;padding:8px 12px;font-weight:700;cursor:pointer}.ib-actions .submit{background:#a6282e;color:#fff;border-color:#a6282e}.ib-save-error{grid-column:1/-1;background:#fff1f1;color:#9b1c1c;border:1px solid #e8a5a5;padding:8px 10px;border-radius:6px}.ib-scroll{overflow:auto;background:#edf0f2;padding:18px}.ib-book,.ib-results-book{display:flex;flex-direction:column;gap:22px;align-items:center}.ib-page{width:794px;min-height:1123px;box-sizing:border-box;background:#fff;position:relative;padding:82px 59px 72px;box-shadow:0 4px 18px rgba(0,0,0,.14);font-size:14px;line-height:1.45}.ib-pagehead{position:absolute;top:31px;left:59px;right:59px;display:grid;grid-template-columns:1fr auto 1fr;font-size:12px}.ib-pagehead span:last-child{text-align:right}.c{position:absolute;width:15px;height:15px}.c:before,.c:after{content:'';position:absolute;background:#333}.c:before{width:15px;height:1.5px}.c:after{height:15px;width:1.5px}.c.tl{left:34px;top:34px}.c.tr{right:34px;top:34px;transform:scaleX(-1)}.c.bl{left:34px;bottom:34px;transform:scaleY(-1)}.c.br{right:34px;bottom:34px;transform:scale(-1)}.ib-opening{font-size:14px;margin:0 0 22px}.ib-qlead{display:grid;grid-template-columns:28px 1fr;gap:10px;margin-bottom:16px}.ib-qlead>b{font-size:16px}.ib-qlead p{margin:0 0 10px}.ib-equation{text-align:center;font-family:'Times New Roman',serif;font-size:17px;margin:13px 0}.ib-source-image{display:block;max-width:92%;height:auto;margin:16px auto}.ib-source-image.q3-electroplating{max-width:78%}.ib-source-image.q5-camp-stove{max-width:77%}.ib-source-note{text-align:center;font-size:10px;color:#555;margin-top:-10px;margin-bottom:12px}.ib-data{border-collapse:collapse;margin:12px auto;min-width:430px}.ib-data td{border:1px solid #8f949a;padding:8px 12px}.ib-overlay-stage,.ib-inline-overlay{position:relative;margin:14px auto}.ib-overlay-stage img,.ib-inline-overlay img{display:block;width:100%;height:auto}.ib-overlay-stage.q1-pathway{width:96%}.ib-overlay-input,.ib-inline-overlay textarea,.ib-inline-overlay-input{position:absolute;box-sizing:border-box;border:none;background:rgba(255,255,255,.90);font:16px/1.3 Arial,sans-serif;padding:5px;resize:none;outline:1px dashed rgba(0,0,0,.12)}.ib-part{margin:18px 0 26px}.ib-part-row{display:grid;grid-template-columns:45px 1fr 36px;gap:8px;align-items:start}.ib-part-row>span{text-align:right}.ib-lead{margin:0 0 10px}.ib-response{position:relative;margin:10px 0 0;border:1px solid #9ca1a8;background:#fff;min-height:78px;overflow:hidden}.ib-response textarea{position:relative;z-index:2;width:100%;box-sizing:border-box;border:0;background:transparent;resize:none;padding:12px 40px;font:14px/27px Arial,Helvetica,sans-serif;min-height:78px;outline:none}.ib-guides{position:absolute;z-index:1;left:40px;right:40px;top:9px;pointer-events:none}.ib-guides i{display:block;height:27px;border-bottom:2px dotted #a8adb3}.ib-part-image{display:block;max-width:78%;margin:12px auto}.ib-inline-overlay{width:78%}.ib-inline-overlay textarea{font-size:15px;text-align:center}.ib-draw-tools{display:flex;gap:6px;justify-content:center;flex-wrap:wrap;margin:9px 0}.ib-draw-tools button{padding:6px 9px;font-size:12px}.ib-draw-tools button.active{background:#205fa8;color:#fff}.ib-draw-stage{position:relative;width:82%;max-width:610px;margin:8px auto}.ib-draw-stage img{display:block;width:100%;height:auto}.ib-draw-stage canvas{position:absolute;inset:0;width:100%;height:100%;touch-action:none}.ib-continued{font-size:13px;margin-bottom:18px}.ib-end-rule{position:absolute;left:59px;right:59px;bottom:58px;border-top:1.5px solid #333}
.ib-cover{padding-top:56px}.cover-logo{position:absolute;right:55px;top:36px;width:66px}.cover-title{font-size:18px;line-height:1.15;margin-top:5px}.cover-title b{font-size:19px}.cover-meta{margin-top:48px;line-height:1.7}.cover-session{margin-top:22px;display:flex;justify-content:space-between;align-items:end}.cover-session>span{font-size:16px}.cover-session label{text-align:right}.cover-session em{display:flex;margin-top:5px}.cover-session em i{display:block;width:24px;height:27px;border:1px solid #777;border-left:0}.cover-session em i:first-child{border-left:1px solid #777}.ib-cover hr{margin:8px 0 10px;border:0;border-top:1.5px solid #333}.ib-cover h3{font-size:15px;margin:0 0 6px}.ib-cover ul{margin:0;padding-left:22px;line-height:1.35}
.ib-mark-page h2{margin-top:0}.ib-mark-part{margin:16px 0;padding:12px;border-left:4px solid #d24b58;background:#fff0f1}.ib-mark-part.good{border-color:#3e9b5e;background:#eff9f2}.ib-mark-box{margin-top:9px;border:1px solid #bbb;background:#fff;padding:9px 11px}.ib-mark-box>div{margin-top:6px;white-space:pre-wrap}.ib-mark-box.feedback{background:#fff9e8}.ib-mark-draw{position:relative;width:82%;max-width:610px;margin:10px auto}.ib-mark-draw img{display:block;width:100%}.ib-mark-draw svg{position:absolute;inset:0;width:100%;height:100%}.ib-summary{text-align:center;padding-top:330px}.ib-summary h1{font-size:28px}.ib-summary div{font-size:42px;font-weight:700}.ib-summary strong{display:block;font-size:32px;margin-top:12px}.ib-ea-login,.ib-ea-loading{padding:16px;background:#fff;border:1px solid #ddd}
@media(max-width:900px){.ib-toolbar{grid-template-columns:1fr}.ib-actions{justify-content:flex-start}.ib-page{width:100%;min-height:auto;padding:60px 30px 55px}.ib-pagehead{left:30px;right:30px}.c{display:none}.ib-scroll{padding:8px}.ib-part-row{grid-template-columns:36px 1fr 30px}.ib-response textarea{padding-left:25px;padding-right:25px}.ib-guides{left:25px;right:25px}.ib-data{min-width:0;width:100%}}
@media print{.ib-toolbar{display:none!important}.ib-scroll{padding:0;background:#fff;overflow:visible}.ib-book,.ib-results-book{gap:0}.ib-page{box-shadow:none;margin:0;width:210mm;min-height:297mm;page-break-after:always}.ib-draw-tools{display:none}.ib-response textarea{overflow:visible;height:auto!important}}
.ib-pause-card{max-width:640px;margin:40px auto;background:#fff;border:1px solid #d6dbe1;border-radius:12px;padding:28px;box-shadow:0 6px 20px rgba(0,0,0,.08)}.ib-pause-card button{border:0;background:#1f5f9f;color:#fff;padding:10px 16px;border-radius:8px;font-weight:700;cursor:pointer}
.ib-mark-overlay-text,.ib-mark-overlay span{position:absolute;box-sizing:border-box;background:#fff;border:1px solid #aeb5bb;padding:4px;font-size:13px;overflow:hidden}.ib-mark-overlay span{position:absolute}.ib-mark-overlay-text.mark-good,.ib-mark-overlay span.mark-good{background:rgba(240,255,244,.94);border-color:#3e9b5e}.ib-mark-overlay-text.mark-bad,.ib-mark-overlay span.mark-bad{background:rgba(255,240,241,.96);border-color:#d24b58}.ib-mark-overlay-text.mark-blank,.ib-mark-overlay span.mark-blank{background:#fff;border-color:#aeb5bb}
.ib-source-image.q5-sealed{max-width:72%}


/* v1.1.1 — match the approved Paper 1 start/resume card */
.ib-start-shell{background:#fff;border:0;box-shadow:none}
.ib-start-card{max-width:940px;margin:10px auto;background:#fff;padding:18px 24px 16px;border:1px solid #d6dade;border-radius:9px;box-shadow:0 2px 9px rgba(0,0,0,.08)}
.ib-start-title-row{display:flex;align-items:flex-start;justify-content:space-between;gap:22px}
.ib-start-title-row h2{font-size:24px;line-height:1.2;margin:0;flex:1;min-width:0;color:#233240}
.ib-start-top-btn{appearance:none;border:0;border-radius:5px;background:#203248;color:#fff;font-weight:700;padding:10px 18px;cursor:pointer;white-space:nowrap;font-size:14px}
.ib-start-top-btn:disabled{opacity:.65;cursor:default}
.ib-start-meta-row{display:flex;align-items:center;gap:10px;margin-top:13px;font-size:17px;line-height:1.3;font-weight:600;color:#2f3942}
.ib-meta-dot{font-weight:700;color:#59636c}
.ib-banner{padding:11px 13px;border-radius:7px;background:#fff4d8;color:#6e4a00;margin:12px 0 0;border:1px solid #ead39b}
.ib-start-card .ib-save-error{margin-top:12px}
.ib-actions .save-exit{background:#e7ebee;color:#1d2b38;border-color:#d3d9de}
@media(max-width:720px){.ib-start-card{margin:8px auto;padding:14px}.ib-start-title-row{align-items:center;gap:12px}.ib-start-title-row h2{font-size:18px}.ib-start-top-btn{font-size:13px;padding:9px 12px}.ib-start-meta-row{font-size:15px;margin-top:10px;flex-wrap:wrap}}


/* v1.1.2 — Paper 2 visual alignment with approved Paper 1 family */
.ib-start-shell{background:#fff!important;padding:12px 0 20px!important;min-height:150px!important;border-radius:10px!important;box-sizing:border-box!important}
.ib-start-card{max-width:860px!important;margin:0 auto!important;padding:26px 28px!important}
.ib-start-title-row h2{font-size:24px!important;color:#233240!important}

/* A4 book scroll: same visible-page behaviour as the approved Paper 1 plugins. */
.ib-scroll{height:min(78vh,920px)!important;max-height:min(78vh,920px)!important;overflow-y:auto!important;overflow-x:hidden!important;scrollbar-gutter:stable;background:#eef1f3!important;padding:18px!important}
.ib-book,.ib-results-book{width:min(100%,794px)!important;margin:0 auto!important;gap:20px!important}
.ib-page{width:100%!important;height:auto!important;min-height:0!important;aspect-ratio:210/297!important;margin:0 auto 20px!important;padding:8.2% 7.4% 7.2%!important;overflow:hidden!important;box-sizing:border-box!important}

/* P2 cover now uses the same family as P1 while keeping P2-specific instructions. */
.ib-cover{padding-top:8.2%!important}
.cover-logo{position:absolute!important;right:calc(9.5% + 10mm)!important;top:3.7%!important;width:10.4%!important;max-width:78px!important;height:auto!important}
.cover-title{font-size:22px!important;font-weight:800!important;line-height:1.12!important;margin-top:3%!important}
.cover-title b{font-size:22px!important}
.cover-sub{margin-top:28px!important;font-size:15px!important}
.cover-time{margin-top:34px!important;font-size:16px!important;border-bottom:1px solid #666!important;padding-bottom:7px!important}
.ib-cover h3{font-size:16px!important;margin:12px 0 7px!important}
.ib-cover ul{margin:0!important;padding-left:20px!important;font-size:14px!important;line-height:1.45!important}
.ib-disclaimer{font-size:12px!important;font-style:italic!important;margin-top:18px!important}
.ib-cover-footer{position:absolute!important;bottom:4%!important;left:7.2%!important;right:7.2%!important;display:flex!important;justify-content:space-between!important;font-size:11px!important}

/* Centre written working boxes cleanly beneath each subpart. */
.ib-response{width:90%!important;margin:10px auto 0!important;box-sizing:border-box!important}
.ib-response textarea{display:block!important;text-align:left!important}

/* Diagram entry fields sit inside the source boxes rather than floating over labels. */
.ib-overlay-stage,.ib-inline-overlay{margin-left:auto!important;margin-right:auto!important}
.ib-overlay-input,.ib-inline-overlay textarea,.ib-inline-overlay-input{display:block!important;text-align:center!important;line-height:1.25!important;padding:5px 7px!important;border:1px solid #aeb5bb!important;outline:none!important;background:rgba(255,255,255,.96)!important;border-radius:2px!important;box-shadow:none!important}

/* The electroplating diagram was too small. */
.ib-source-image.q3-electroplating{width:94%!important;max-width:94%!important;max-height:none!important;margin:12px auto 14px!important}
.ib-source-note{display:none!important}

/* Make every plugin button readable even when theme button styles leak in. */
.ib-actions button,.ib-draw-tools button,.ib-start-top-btn{appearance:none!important;-webkit-appearance:none!important;opacity:1!important;text-shadow:none!important;box-shadow:none!important;font-family:Arial,Helvetica,sans-serif!important;font-weight:700!important;line-height:1.15!important}
.ib-actions button{background:#203248!important;border:1px solid #203248!important;color:#fff!important;-webkit-text-fill-color:#fff!important;padding:8px 12px!important;border-radius:5px!important}
.ib-actions .save-exit{background:#e7ebee!important;border-color:#d3d9de!important;color:#1d2b38!important;-webkit-text-fill-color:#1d2b38!important}
.ib-actions .submit{background:#a12e36!important;border-color:#a12e36!important;color:#fff!important;-webkit-text-fill-color:#fff!important}
.ib-draw-tools button{background:#f4f6f7!important;border:1px solid #8d969e!important;color:#1e2c36!important;-webkit-text-fill-color:#1e2c36!important;padding:6px 9px!important;border-radius:3px!important;font-size:12px!important}
.ib-draw-tools button.active{background:#245f8e!important;border-color:#245f8e!important;color:#fff!important;-webkit-text-fill-color:#fff!important}
.ib-actions button:disabled,.ib-draw-tools button:disabled,.ib-start-top-btn:disabled{opacity:.65!important}

/* Grammarly and similar injected UI must not disturb exam answer boxes. */
.ib-ea-root grammarly-extension,.ib-ea-root grammarly-popups,.ib-ea-root [data-grammarly-part]{display:none!important}
.ib-ea-root textarea{background-clip:padding-box!important}

@media(max-width:900px){
  .ib-scroll{height:min(78vh,920px)!important;max-height:min(78vh,920px)!important;padding:8px!important}
  .ib-page{aspect-ratio:auto!important;min-height:1123px!important;padding:60px 30px 55px!important}
  .ib-response{width:94%!important}
  .ib-source-image.q3-electroplating{width:100%!important;max-width:100%!important}
}

/* Diagram answer fields are true single-line inputs: no textarea scrollbars or spinner/scroll UI. */
.ib-overlay-input,.ib-inline-overlay-input{overflow:hidden!important;resize:none!important;appearance:none!important;-webkit-appearance:none!important;-moz-appearance:textfield!important;scrollbar-width:none!important;-ms-overflow-style:none!important}
.ib-overlay-input::-webkit-scrollbar,.ib-inline-overlay-input::-webkit-scrollbar{display:none!important;width:0!important;height:0!important}

/* Written answer boxes are fixed-size like IB papers. */
.ib-response textarea{overflow:hidden!important;resize:none!important;max-width:100%!important}

/* Marked review pages must never clip feedback/markscheme. Live exam pages stay fixed A4; marked pages may extend vertically when a full marked question needs more room. */
.ib-results-book .ib-page{aspect-ratio:auto!important;min-height:1123px!important;height:auto!important;overflow:visible!important}
.ib-results-book .ib-mark-page{padding-bottom:72px!important}

/* v1.1.8 hard replacement: compact Q3 image, deliberately new filename to defeat browser/CDN cache. */
.ib-source-image.q3-electroplating{width:92%!important;max-width:92%!important;height:auto!important;margin:4px auto 6px!important;display:block!important}

/* v1.1.9: response boxes use only the height required by their allotted writing lines. */
.ib-response{min-height:0!important}
.ib-response textarea{min-height:0!important;overflow:hidden!important;resize:none!important}

/* v1.1.10: diagram-entry marking is binary visually: blank/incorrect red, fully correct green. */
.ib-mark-overlay-text.mark-blank,.ib-mark-overlay span.mark-blank{background:rgba(255,240,241,.96)!important;border-color:#d24b58!important}

/* Preserve marked red/green feedback shading when printing/saving to PDF. */
@media print{
  .ib-results-book .ib-mark-page,.ib-results-book .ib-mark-page *{
    -webkit-print-color-adjust:exact!important;
    print-color-adjust:exact!important;
  }
  .ib-mark-overlay-text.mark-good,.ib-mark-overlay span.mark-good{background:rgb(240,255,244)!important;border-color:#3e9b5e!important}
  .ib-mark-overlay-text.mark-bad,.ib-mark-overlay span.mark-bad,
  .ib-mark-overlay-text.mark-blank,.ib-mark-overlay span.mark-blank{background:rgb(255,240,241)!important;border-color:#d24b58!important}
}

/* Authentic IB continuation labels are bold. */
.ib-continued{font-weight:700!important;}

/* v1.0.0: authentic diagram overlays. The printed diagram supplies the box; live inputs must not draw a second box. */
.ib-overlay-input,.ib-inline-overlay-input{
  border:0!important;
  outline:0!important;
  background:transparent!important;
  border-radius:0!important;
  box-shadow:none!important;
  padding:4px 8px!important;
}
.ib-overlay-input:focus,.ib-inline-overlay-input:focus{
  border:0!important;
  outline:0!important;
  background:rgba(255,255,255,.28)!important;
  box-shadow:none!important;
}

.ib-final-rule{width:75%;border-top:1.5px solid #333;margin:18px auto 0}
/* v1.0.9 standard chemical structure editor, ported from U2 T1 Lewis/VSEPR/IMF Homework */
.ib-chem-editor{margin:10px 0 14px;border:1px solid #bfd0df;border-radius:8px;overflow:hidden;background:#fff}.ib-chem-tools{display:flex;align-items:center;flex-wrap:wrap;gap:5px;padding:7px;background:#edf3f8;border-bottom:1px solid #c3d1de}.ib-chem-tools button{height:32px;border:1px solid #aebfce;background:#fff;color:#29455f;border-radius:5px;font-size:9px;font-weight:800;padding:0 9px;cursor:pointer}.ib-chem-tools button[data-atom]{min-width:34px;font-size:12px;color:#123e69}.ib-chem-tools button.active{background:#142b44;color:#fff;border-color:#142b44}.ib-chem-tools span{width:1px;height:24px;background:#bdcbd7;margin:0 2px}.ib-chem-stage{position:relative;height:360px;background-color:#fff;background-image:radial-gradient(#d8e1e9 1px,transparent 1.2px);background-size:34px 34px;overflow:hidden;touch-action:none}.ib-chem-stage canvas{position:absolute;inset:0;width:100%;height:100%;z-index:1}.ib-chem-objects{position:absolute;inset:0;z-index:2}.ib-chem-object{position:absolute;transform:translate(-50%,-50%);user-select:none;cursor:move;color:#111827}.ib-chem-object.atom{font-size:24px;font-weight:700;background:rgba(255,255,255,.94);padding:1px 3px;border-radius:3px}.ib-chem-object.lone{font-size:21px;font-weight:900;letter-spacing:2px}.ib-chem-object.charge{font-size:19px;font-weight:800}.ib-chem-object.bracket{font-size:64px;font-family:Georgia,serif}.ib-mark-draw.chem{background:#fff;border:1px solid #b8c4ce;min-height:220px}.ib-chem-review{display:block;width:100%;height:250px;background:#fff}.ib-chem-review line{stroke:#111827;stroke-width:2.5}.ib-chem-review text{font:700 26px Arial,sans-serif;fill:#111827;text-anchor:middle;dominant-baseline:middle}.ib-chem-review text.lone{font-size:22px}.ib-chem-review text.bracket{font:58px Georgia,serif}.ib-chem-model{padding-top:8px}.ib-chem-model .formula{font:700 18px Arial,sans-serif;letter-spacing:.3px;margin:8px 0 12px;padding:8px 10px;border:1px solid #cbd5df;background:#fff}

/* v1.0.11: graphical markscheme structures. */
.ib-model-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin-top:8px}.ib-chem-model-figure{margin:8px 0 12px;padding:8px;border:1px solid #cbd5df;background:#fff}.ib-model-structure{display:block;width:100%;height:auto;max-height:265px;object-fit:contain}.ib-chem-model-figure figcaption{text-align:center;font-weight:700;margin-top:6px}.ib-chem-model small{display:block;line-height:1.35}@media(max-width:700px){.ib-model-grid{grid-template-columns:1fr}}

/* v1.0.12: q7(b)(iii) full displayed structures are embedded inline to avoid cached/blocked SVG image fallbacks. */
.ib-full-structure-stack{display:grid;grid-template-columns:1fr;gap:12px;margin-top:8px}.ib-chem-model-figure.inline{max-width:760px;margin:8px auto 12px;width:100%}.ib-inline-struct-svg{display:block;width:100%;height:auto;max-height:285px;background:#fff}

/* v1.0.13 structured mechanism drawing */
.ib-mech-editor{margin:10px 0 14px;border:1px solid #bfd0df;border-radius:8px;overflow:hidden;background:#fff}
.ib-mech-tools{display:flex;align-items:center;flex-wrap:wrap;gap:5px;padding:7px;background:#edf3f8;border-bottom:1px solid #c3d1de}
.ib-mech-tools button{height:32px;border:1px solid #aebfce;background:#fff;color:#29455f;border-radius:5px;font-size:9px;font-weight:800;padding:0 8px;cursor:pointer}
.ib-mech-tools button[data-matom]{min-width:34px;font-size:12px;color:#123e69}.ib-mech-tools button.active{background:#142b44;color:#fff;border-color:#142b44}
.ib-mech-tools span{width:1px;height:24px;background:#bdcbd7;margin:0 2px}.ib-mech-help{padding:5px 10px;background:#f8fbfd;color:#52687c;font-size:11px;border-bottom:1px solid #d8e2ea}
.ib-mech-stage{position:relative;height:360px;background-color:#fff;background-image:radial-gradient(#d8e1e9 1px,transparent 1.2px);background-size:34px 34px;overflow:hidden;touch-action:none}
.ib-mech-stage canvas{position:absolute;inset:0;width:100%;height:100%;z-index:1}.ib-mech-objects{position:absolute;inset:0;z-index:2}
.ib-mech-object{position:absolute;transform:translate(-50%,-50%);user-select:none;cursor:move;color:#111827}.ib-mech-object.atom{font-size:24px;font-weight:700;background:rgba(255,255,255,.94);padding:1px 3px;border-radius:3px}
.ib-mech-object.lone{font-size:20px;font-weight:900;letter-spacing:2px}.ib-mech-object.radical{font-size:24px;font-weight:900}.ib-mech-object.charge{font-size:20px;font-weight:800}
.ib-mech-object.condition{font-size:16px;font-weight:700;background:rgba(255,255,255,.94);padding:2px 4px;border-radius:3px}
.ib-mark-draw.mechanism{background:#fff;border:1px solid #b8c4ce;min-height:240px}.ib-mech-review{display:block;width:100%;height:260px;background:#fff}
.ib-mech-review line,.ib-mech-review path{stroke:#111827;stroke-width:2.5;fill:none}.ib-mech-review text{font:700 27px Arial,sans-serif;fill:#111827;text-anchor:middle;dominant-baseline:middle}
.ib-mech-review text.radical,.ib-mech-review text.charge{font-size:22px}.ib-mech-review text.condition{font-size:17px}
.ib-mech-model{margin-top:8px}.ib-mech-model-svg{display:block;width:100%;max-width:780px;height:auto;margin:8px auto;background:#fff;border:1px solid #cbd5df}
.ib-mech-model-svg line,.ib-mech-model-svg path{stroke:#111827;stroke-width:3;fill:none;stroke-linecap:round}.ib-mech-model-svg text{font:700 30px Arial,sans-serif;fill:#111827;text-anchor:middle;dominant-baseline:middle}
.ib-mech-model-svg text.cond{font-size:18px}.ib-mech-model-svg text.rad,.ib-mech-model-svg text.charge{font-size:24px}
.ib-mark-box.drawing-response{padding-bottom:10px}.ib-mark-box.drawing-response>.ib-mark-draw{margin-top:8px}.ib-empty-drawing{padding:24px;color:#666;text-align:center}
.ib-part-row sub{font-size:.75em;vertical-align:sub;line-height:0}

/* v1.0.14 mechanism editor controls: moveable arrows/symbols and compact chemical-arrow icons */
.ib-mech-tools button{min-width:32px}.ib-mech-tools button[data-mtool="move"]{min-width:54px}.ib-mech-tools button[data-mtool="reaction"],.ib-mech-tools button[data-mtool="reversible"],.ib-mech-tools button[data-mtool="plus"],.ib-mech-tools button[data-mtool="chargePlus"],.ib-mech-tools button[data-mtool="chargeMinus"],.ib-mech-tools button[data-mtool="radical"],.ib-mech-tools button[data-mtool="lone"]{font-size:18px;line-height:1}.ib-mech-tools .ib-arrow-icon{width:42px;padding:2px 5px}.ib-mech-tools .ib-arrow-icon svg{width:30px;height:22px;display:block}.ib-mech-tools .ib-arrow-icon svg path{stroke:currentColor;stroke-width:2;fill:none;stroke-linecap:round;stroke-linejoin:round}.ib-mech-tools .ib-arrow-icon svg path.fill{fill:currentColor;stroke:none}.ib-mech-object.symbol{font-size:28px;font-weight:700;background:rgba(255,255,255,.96);padding:0 4px;border-radius:3px}.ib-mech-review text.symbol{font-size:30px}.ib-mech-stage{cursor:crosshair}.ib-mech-editor:has([data-mtool="move"].active) .ib-mech-stage{cursor:move}

/* v1.0.15 mechanism arrow placement preview + explicit bond labels */
.ib-mech-tools button[data-mtool="bond1"],
.ib-mech-tools button[data-mtool="bond2"],
.ib-mech-tools button[data-mtool="bond3"],
.ib-mech-tools button[data-mtool="bonddot"]{font-size:9px;line-height:1.05;min-width:auto;padding:0 8px;white-space:nowrap}
.ib-mech-tools .ib-arrow-symbol{font-size:25px!important;line-height:1;min-width:44px!important;font-family:"Segoe UI Symbol","Arial Unicode MS",sans-serif;font-weight:700}
.ib-mech-tools .ib-reversible-symbol{font-size:28px!important;letter-spacing:-2px}
.ib-mech-tools .ib-arrow-icon{width:54px!important;height:34px!important;padding:2px 4px!important}
.ib-mech-tools .ib-arrow-icon svg{width:44px!important;height:26px!important;display:block}
.ib-mech-tools .ib-arrow-icon svg path{stroke:currentColor;stroke-width:2.5;fill:none;stroke-linecap:round;stroke-linejoin:round}
.ib-mech-tools .ib-arrow-icon svg path.fill{fill:currentColor;stroke:none}
.ib-mech-tools .ib-arrow-icon svg path.barb{stroke-width:3.2}
.ib-mech-editor:has([data-mtool="reaction"].active) .ib-mech-stage,
.ib-mech-editor:has([data-mtool="reversible"].active) .ib-mech-stage,
.ib-mech-editor:has([data-mtool="curved"].active) .ib-mech-stage,
.ib-mech-editor:has([data-mtool="fish"].active) .ib-mech-stage{cursor:crosshair}

/* v1.0.16 mechanism-tool clarity and arrow selection */
.ib-mech-tools button[data-mtool="radical"]{font-size:9px!important;line-height:1.05!important;min-width:auto!important;padding:0 8px!important;white-space:nowrap}
.ib-mech-tools button[data-mtool="bracketL"],.ib-mech-tools button[data-mtool="bracketR"]{font-size:18px!important;min-width:34px!important}
.ib-mech-tools .ib-eq-arrow-icon{width:58px!important;height:34px!important;padding:2px 4px!important}
.ib-mech-tools .ib-eq-arrow-icon svg{width:48px!important;height:26px!important;display:block}
.ib-mech-tools .ib-eq-arrow-icon svg path{stroke:currentColor;stroke-width:2.4;fill:none;stroke-linecap:round;stroke-linejoin:round}
.ib-mech-tools button[data-maction="flip"]{min-width:76px;white-space:nowrap}
.ib-mech-tools button[data-maction="flip"]:disabled{opacity:.45;cursor:not-allowed;background:#f4f7f9;color:#6d7e8d}
.ib-mech-object.bracket{font-size:64px;font-family:Georgia,serif;line-height:1}
.ib-mech-review text.bracket{font:58px Georgia,serif}
/* v1.0.17 clearer mechanism review/model arrows */
.ib-mech-model-note{margin:6px 4px 2px;font-size:12px;line-height:1.4;color:#334155}
.ib-mech-model-svg text.plus{font-size:26px}
.ib-mech-review marker path,.ib-mech-model-svg marker path{fill:none!important;stroke-linecap:round;stroke-linejoin:round}