:root{--teal:#167778;--ink:#20333e;--muted:#5f6d77;--line:#e2e7ea;--dark:#122430;--mint:#68d7c6}*{box-sizing:border-box}body{margin:0;font:13px Arial,sans-serif;color:var(--ink);background:#f2f6f8}button,select,input{font:inherit}button,a,select,input{touch-action:manipulation}button{cursor:pointer}a{color:inherit;text-decoration:none}button{background:white;border:1px solid var(--line);border-radius:5px;color:var(--ink);padding:9px 12px}button:hover{background:#eff6f5}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #69bdbb;outline-offset:2px}.platform-bar{height:35px;padding:0 18px;background:#f8f9fc;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;font-size:12px}.platform-bar strong{font-size:16px;letter-spacing:-.7px}.platform-bar a span{border-left:1px solid #cfd5dd;margin-left:10px;padding-left:10px;color:#5f6c76}.platform-bar button{padding:0;border:0;background:transparent;font-size:12px}header{height:78px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;padding:0 24px;gap:26px}.app-title{display:flex;align-items:center;gap:12px}.app-icon{width:36px;height:40px;border-radius:9px;background:var(--dark);color:var(--mint);font-size:40px;text-align:center;line-height:32px}h1{font-size:23px;letter-spacing:-.7px;margin:0 0 4px}header small{font-size:11px;color:var(--muted);letter-spacing:1.2px}.header-description{border-left:1px solid var(--line);padding-left:24px;color:var(--muted);font-size:12px}.header-actions{margin-left:auto;display:flex;gap:18px;align-items:center}.primary{background:var(--teal);border-color:var(--teal);color:white;padding:11px 18px}.primary:hover{background:#126465}#help-icon{border-radius:50%;padding:0;width:23px;height:23px;color:var(--muted)}.workspace{height:calc(100dvh - 113px);display:grid;grid-template-columns:218px minmax(0,1fr) 280px}.library,aside{background:#fff;padding:24px 18px;overflow:auto}.library{border-right:1px solid var(--line);display:flex;flex-direction:column}h2{font-size:14px;margin:0;font-weight:600}h2 small{float:right;font-size:11px;font-weight:400;color:var(--muted);border:1px solid var(--line);padding:1px 4px}.muted{font-size:11px;color:var(--muted);line-height:1.6;margin:9px 0 20px}nav{display:flex;flex-direction:column;gap:6px}nav button,.challenge{display:flex;gap:12px;align-items:center;text-align:left;padding:13px 10px;width:100%}nav button{border-color:transparent;background:#f8fafb}nav button>span{font-size:30px;color:var(--teal);width:25px}nav button.active{background:#eaf5f2;border-color:#c0dfd8;color:#126664}nav small,.challenge small{display:block;font-size:11px;color:var(--muted);margin-top:5px}h3{font-size:11px;color:var(--muted);font-weight:400;margin:30px 0 10px}.challenge{border:0;border-bottom:1px solid #edf0f2;border-radius:0;background:transparent;font-size:12px}.challenge>span{color:#587579;font-size:11px}.formula{margin-top:32px;padding:18px 12px;background:#f6f9fa;border-radius:6px}.formula>span{font-size:11px;letter-spacing:1px;color:var(--muted)}.formula strong{display:block;font-family:Georgia,serif;font-style:italic;font-weight:400;font-size:26px;margin:12px 0;color:var(--teal)}.formula p{font-size:11px;line-height:1.7;color:var(--muted);margin:0}.local-note{font-size:11px;color:var(--muted);margin-top:auto;padding-top:30px}.stage{min-width:0;min-height:0;background:var(--dark);display:flex;flex-direction:column;color:#bdcbd3}.stage-top{height:54px;flex-shrink:0;display:flex;justify-content:space-between;align-items:center;padding:0 15px;background:#192f3c;border-bottom:1px solid #2b404c;gap:8px}.tools{display:flex;gap:5px}.small{font-size:11px;padding:7px 9px;border-color:#38505c;background:transparent;color:#c3d1d9}.small:hover,.small.active{background:#2b535a;color:#91ded1;border-color:#2b535a}.animation-speed{font-size:11px;color:#9fadb6;display:flex;align-items:center;gap:6px}.animation-speed select{background:#223d4a;color:#d3e2e7;border:1px solid #3b535f;border-radius:4px;padding:5px}.canvas-wrap{position:relative;flex:1;min-height:200px;background-image:radial-gradient(#34505e77 1px,transparent 1px);background-size:24px 24px}.scene-heading{position:absolute;top:22px;left:24px;right:24px;display:flex;gap:16px;font-size:11px}.scene-heading i,.status-bar i{width:5px;height:5px;display:inline-block;border-radius:50%;background:#6dd6bd;margin-right:8px}.scene-model{border-left:1px solid #42525d;padding-left:16px;color:#79929f}#scene{display:block;width:100%;height:100%;position:absolute;inset:0}.scene-caption{position:absolute;bottom:15px;left:24px;right:24px;display:flex;justify-content:space-between;pointer-events:none;font-size:11px;letter-spacing:.6px;color:#7893a2}.legend{display:flex;padding:10px 24px;gap:20px;font-size:11px;color:#94a9b4;border-bottom:1px solid #2b404c}.legend > span:last-child{margin-left:auto}.blue-dot,.orange-dot{width:5px;height:5px;display:inline-block;border-radius:50%;background:var(--mint);margin-right:6px}.orange-dot{background:#efb76f}.graph-section{height:154px;flex-shrink:0;background:#10212c}.graph-head{display:flex;justify-content:space-between;padding:15px 24px 0;font-size:11px;color:#8fa6b3;gap:10px}#graph{height:120px;width:100%;display:block}.metrics{display:grid;grid-template-columns:repeat(3,1fr);border-top:1px solid #2b404c;padding:18px 24px;gap:15px}.metrics div+div{border-left:1px solid #2b404c;padding-left:20px}.metrics small{display:block;font-size:11px;letter-spacing:.9px;color:#7e99a8;margin-bottom:9px}.metrics em{color:#68d7c6;margin-left:5px}.metrics strong{font-size:23px;font-weight:400;color:#edf5f5}.status-bar{display:flex;justify-content:space-between;background:#192f3c;padding:9px 20px;font-size:11px;color:#92a6b1;border-top:1px solid #2b404c}aside{border-left:1px solid var(--line);padding:24px 20px}.control-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:28px}.control-heading button{border:0;font-size:20px;background:#f4f7f8;padding:3px 7px;color:var(--muted)}aside label{display:flex;justify-content:space-between;font-size:12px;font-weight:600;margin-top:25px}output{color:var(--teal);font-size:12px}input[type=range]{width:100%;accent-color:var(--teal);margin:15px 0 8px;cursor:pointer;height:5px}.range-label{display:flex;justify-content:space-between;font-size:11px;color:var(--muted)}aside select{width:100%;background:#f7f9fa;border:1px solid var(--line);padding:10px 8px;border-radius:5px;font-size:11px;color:var(--ink);margin-top:10px}.preset-label{margin:26px 0 12px;font-size:11px;color:var(--muted);letter-spacing:.6px}.presets{display:flex;gap:6px}.presets button{flex:1;padding:8px 3px;font-size:11px}.presets small{display:block;font-size:11px;color:var(--muted);margin-top:5px}.presets .active{color:var(--teal);border-color:#a5ccc5;background:#edf7f3}.note{display:flex;gap:10px;border-top:1px solid var(--line);padding-top:20px;margin-top:27px}.note>span{color:var(--teal)}.note strong{font-size:12px}.note p{font-size:11px;line-height:1.7;color:var(--muted);margin:8px 0 0}dialog{border:1px solid var(--line);border-radius:12px;max-width:600px;width:calc(100% - 32px);padding:26px;color:var(--ink);box-shadow:0 20px 90px #071d3550}dialog::backdrop{background:#0a202a80;backdrop-filter:blur(3px)}.dialog-top{display:flex;justify-content:space-between;align-items:center;gap:10px}.dialog-top button{font-size:20px;border:0}dialog p{font-size:13px;line-height:1.8;color:#657984}details{border-top:1px solid var(--line);padding-top:16px;font-size:12px}summary{cursor:pointer;color:var(--teal)}[hidden]{display:none!important}@media(min-width:1500px){.workspace{grid-template-columns:240px minmax(0,1fr) 310px}}@media(max-width:1050px){.workspace{grid-template-columns:170px minmax(0,1fr) 245px}.library,aside{padding:18px 12px}.legend{gap:10px;padding:10px 15px}.legend > span:last-child{display:none}.animation-speed{font-size:0}.metrics{padding:16px}.metrics div+div{padding-left:12px}.metrics strong{font-size:20px}.small{font-size:11px;padding:7px}.header-description{display:none}.scene-model{display:none}}@media(max-width:760px){.workspace{height:auto;grid-template-columns:minmax(0,1fr)}header{height:70px;padding:0 14px;gap:10px}h1{font-size:19px}.header-actions{gap:8px}.primary{padding:9px 11px;font-size:11px}.platform-bar{font-size:11px;padding:0 12px}.platform-bar button{font-size:11px}.library{border:0;padding:10px 12px;display:block}.library h2,.library>.muted,.library h3,.formula,.local-note,.challenge{display:none}nav{flex-direction:row}nav button{flex:1;padding:7px 12px}nav button>span{font-size:23px}nav small{display:none}.stage{height:calc(100dvh - 162px);min-height:530px}.graph-section{height:132px}#graph{height:100px}.metrics{padding:14px}.metrics small{font-size:7px;letter-spacing:.3px}.metrics strong{font-size:19px}.status-bar{padding:9px 12px;font-size:11px}.scene-heading{top:15px;left:18px}aside{border:0;padding:22px}.control-heading{margin-bottom:15px}.note{margin-bottom:10px}.stage-top{padding:0 10px}.graph-head{padding-left:15px;padding-right:15px}}
.animation-speed select{font-size:11px}
@media(min-width:761px) and (max-width:900px){.workspace{grid-template-columns:155px minmax(0,1fr) 230px}.library{padding-left:10px;padding-right:10px}.scene-heading{left:16px}.legend{font-size:11px;gap:9px;padding:10px}.graph-head{font-size:11px;padding-left:14px;padding-right:14px}.metrics{gap:8px;padding:15px 12px}.metrics div+div{padding-left:8px}.metrics small{font-size:7px;letter-spacing:.3px}}
.languages{display:flex;background:#f1f5f6;padding:3px;border-radius:6px;gap:2px}.languages button{border:0;background:transparent;font-size:11px;color:#5f6d77;padding:7px 8px}.languages button[aria-pressed=true]{background:#fff;color:#166c6c;box-shadow:0 1px 4px #20333e15;font-weight:600}dialog a{color:var(--teal);text-decoration:underline}.scene-model{max-width:55%}.graph-head{flex-wrap:wrap;row-gap:4px}.scene-caption{gap:15px}.header-actions{gap:12px}@media(max-width:600px){header{flex-wrap:wrap;height:auto;min-height:108px;padding-top:10px;padding-bottom:10px}.header-actions{margin-left:0;width:100%;justify-content:flex-end}.app-title{position:absolute;top:46px}.header-actions .languages{margin-right:auto;margin-top:44px}.header-actions .primary{margin-top:44px}#help-icon{margin-top:44px}.stage{height:calc(100dvh - 214px)}.graph-head{font-size:11px}.scene-caption{font-size:11px}.scene-model{display:none}}
/* Doppler workspace: every canvas has an explicitly bounded region. */
nav b,.challenge b{font-weight:400}.app-icon{font-size:31px;line-height:40px;color:#bfb1ed}.workspace{grid-template-columns:205px minmax(0,1fr) 270px;grid-template-rows:minmax(0,1fr);height:calc(100dvh - 113px);min-height:0}.library,aside{min-width:0;min-height:0;overscroll-behavior:contain}.library nav button{padding:11px 8px}.formula strong{font-size:17px;line-height:1.7}.stage{display:grid;grid-template-rows:44px minmax(0,1fr) 30px 150px 52px 72px 28px;min-height:0;height:100%;overflow:hidden}.stage-top{height:auto}.badge{font-size:11px;color:#8da7b2;white-space:nowrap}.field{min-width:0;min-height:0;position:relative;background-image:radial-gradient(#35536266 1px,transparent 1px);background-size:24px 24px;overflow:hidden}#field{position:absolute;inset:0;width:100%;height:100%;touch-action:none;cursor:crosshair}.scene-heading,.scene-caption{z-index:1;pointer-events:none;left:18px;right:18px}.scene-heading{top:16px;justify-content:space-between}.scene-heading>span:last-child{color:#9cddd0}.scene-caption{bottom:12px;letter-spacing:0;font-size:11px}.legend{align-items:center;padding:7px 18px;gap:18px}.legend>span{display:flex;align-items:center;gap:3px}.legend > span:last-child{margin-left:0}.legend>span:last-child{margin-left:auto}.frequency-plot{display:flex;flex-direction:column;min-height:0;background:#10212c;border-bottom:1px solid #2c414e}.graph-head{padding:12px 18px 0;flex:0 0 30px;font-size:11px}.key{display:inline-block;width:14px;height:2px;vertical-align:middle;margin:0 5px 0 12px}.mint{background:#68d7c6}.peach{background:#eeb77c}#chart{display:block;flex:1 1 0;min-height:0;height:0;width:100%}.timeline{display:flex;align-items:center;gap:12px;padding:8px 18px;background:#19313e}.timeline button{background:#244653;color:#b4d7dc;border-color:#365565;white-space:nowrap;font-size:11px;padding:7px}.timeline label{font-size:11px}.timeline input{margin:0;accent-color:#6fd4c0;flex:1;min-width:20px}.timeline output{color:#c6dce2;min-width:48px;font-size:11px}.metrics{padding:12px 18px;align-items:center}.metrics small{margin-bottom:6px}.metrics strong{font-size:22px}.status-bar{padding:7px 18px;font-size:11px;align-items:center;overflow:hidden;gap:10px}.status-bar>span:last-child{white-space:nowrap}.divider{border-top:1px solid var(--line);margin:20px 0 0}.model-button{border:0;color:var(--teal);font-size:11px;padding:16px 0}.header-actions{gap:10px}.note{margin-top:20px}dialog{max-height:85dvh;overflow:auto}dialog h3{font-weight:600;color:var(--teal);font-size:13px}.small[aria-pressed=true]{background:#2b535a;color:#91ded1}.library nav button[aria-pressed=true]{background:#eaf5f2;border-color:#c0dfd8}.legend span{display:flex}.header-actions #reset{font-size:11px}.languages{flex-shrink:0}
@media(min-width:761px) and (max-width:1100px){.workspace{grid-template-columns:150px minmax(0,1fr) 220px}.header-description{display:none}.scene-caption>span:last-child,.status-bar>span:last-child{display:none}.badge{display:none}.metrics{padding:10px;gap:8px}.metrics div+div{padding-left:8px}.metrics strong{font-size:18px}.metrics small{letter-spacing:0;font-size:7px}.small{font-size:11px;padding:7px}.stage-top{padding:0 8px}.scene-heading{font-size:11px;gap:5px}}
@media(min-width:761px) and (max-height:700px){.platform-bar{height:30px}header{height:64px}.workspace{height:calc(100dvh - 94px)}.stage{grid-template-rows:40px minmax(0,1fr) 28px 108px 44px 58px 24px}.metrics{padding:8px 14px}.metrics strong{font-size:19px}.scene-heading{top:10px}.scene-caption{bottom:8px}.graph-head{padding-top:7px;flex-basis:23px}}
@media(max-width:760px){header{height:auto;min-height:105px;flex-wrap:wrap;padding:12px 16px;gap:12px}.app-title{position:static;width:100%}h1{font-size:20px}.header-description{display:none}.header-actions{width:100%;margin:0;justify-content:flex-end}.header-actions .languages{margin:0 auto 0 0}.header-actions .primary{margin:0}.workspace{height:auto;grid-template-columns:minmax(0,1fr);grid-template-rows:auto auto auto}.library nav{overflow-x:auto}.library nav button{min-width:125px}.stage{height:730px;min-height:0;grid-template-rows:44px minmax(0,1fr) 30px 145px 48px 66px 28px}.scene-caption>span:last-child,.status-bar>span:last-child,.badge{display:none}.scene-heading{font-size:11px;gap:8px}.legend>span:last-child{display:none}.metrics{padding:12px;gap:8px}.metrics div+div{padding-left:8px}.metrics strong{font-size:18px}.timeline{gap:8px;padding:8px 12px}.timeline label{display:none}.platform-bar button{font-size:11px}.stage-top{padding:0 10px}.small{font-size:11px;padding:7px}.legend{font-size:11px}}
.stage{grid-template-rows:44px minmax(0,1fr) 30px 132px 72px 28px}.field{background:#080e1d}.app-icon{color:#d5b5f3}.geometry{display:flex;flex-direction:column;min-height:0;background:#10212c;border-bottom:1px solid #29404d}#diagram{flex:1 1 0;min-height:0;height:0;width:100%;display:block}#field{cursor:grab;touch-action:none}#field:active{cursor:grabbing}.source-preview{display:flex;align-items:center;gap:12px;margin-top:18px;background:#101b2c;border-radius:6px;padding:6px 12px;color:#93a8bb;font-size:11px;line-height:1.5}#source-preview{width:75px;height:75px;flex-shrink:0}.formula strong{font-size:17px}.scene-heading{color:#bbc3d7}.scene-heading>span:last-child{color:#cbb1ea}.scene-caption{color:#8590ac}.legend .blue-dot{background:#83b8f4}.legend .orange-dot{background:#edbd93}.metrics strong{font-size:20px}.metrics small{letter-spacing:.5px}.small[aria-pressed=false]{opacity:.65}
@media(min-width:761px) and (max-height:700px){.stage{grid-template-rows:40px minmax(0,1fr) 28px 100px 58px 24px}}
@media(max-width:1100px){.metrics{padding:10px}.metrics strong{font-size:17px}.scene-heading>span:last-child{display:none}}
@media(max-width:760px){.stage{height:730px;grid-template-rows:44px minmax(0,1fr) 30px 130px 66px 28px}.scene-caption>span:last-child{display:none}.metrics strong{font-size:17px}.header-actions .languages{margin:0 auto 0 0}.legend{font-size:11px;gap:10px}}
.stage{grid-template-rows:44px minmax(0,1fr) 30px 60px 74px 28px}.field{background:#080d19}#field{cursor:crosshair}.app-icon{color:#d6b6f1;text-shadow:0 0 7px #9274bd}.launch-row{display:flex;align-items:center;gap:12px;padding:10px 18px;background:#172c3a;border-bottom:1px solid #304453}.launch-row .primary{font-size:12px;padding:9px 16px}.launch-row>span{margin-left:auto;color:#849bad;font-size:11px}.threshold{background:#f3f6fa;border:1px solid #e4e8ee;border-radius:6px;padding:14px;margin-top:18px}.threshold>span{font-size:11px;color:#5f6d77}.threshold strong{display:block;color:#806699;font-size:17px;margin-top:8px;font-weight:400}.threshold p{font-size:11px;line-height:1.6;color:#5f6d77;margin:8px 0 0}.metrics strong{font-size:19px}.metrics small{font-size:11px}.legend .blue-dot{background:#74ddce}.legend .orange-dot{background:#d4b6ed}.library nav button{padding:9px 8px}.scene-heading{z-index:1}.scene-heading>span:last-child{color:#d7b5eb}
@media(min-width:761px) and (max-height:700px){.stage{grid-template-rows:40px minmax(0,1fr) 28px 50px 58px 24px}.launch-row{padding:6px 12px}.metrics strong{font-size:17px}}
@media(max-width:1100px){.launch-row>span{display:none}.launch-row{gap:8px}.metrics strong{font-size:15px}}
@media(max-width:760px){.stage{height:730px;grid-template-rows:44px minmax(0,1fr) 30px 56px 70px 28px}.launch-row{padding:8px 12px}.metrics strong{font-size:15px}.metrics{gap:6px}.metrics small{font-size:7px}.header-actions .languages{margin:0 auto 0 0}.legend{gap:10px;font-size:11px}}
/* Four complementary views, each with an explicit physical interpretation. */
.stage{grid-template-rows:44px 42px minmax(0,1fr) 30px 60px 74px 28px}.view-tabs{display:flex;gap:0;background:#111f30;border-bottom:1px solid #304052;overflow-x:auto;min-width:0}.view-tabs button{white-space:nowrap;flex:1;border:0;border-bottom:2px solid transparent;border-radius:0;background:none;color:#899eae;font-size:11px;padding:10px}.view-tabs button[aria-pressed=true]{background:#213849;color:#b5f1e0;border-color:#79d7c1}.mode-info{padding:14px;background:#f0f6f6;border:1px solid #dbe8e6;border-radius:7px;margin-bottom:18px}.mode-info strong{font-size:12px;line-height:1.5;display:block;color:#25505b}.mode-info p{font-size:11px;line-height:1.65;color:#5f6d77;margin:8px 0 0}.camera-actions{display:flex;gap:6px}.camera-actions button{font-size:11px;flex:1;padding:8px 4px}.camera-actions button[aria-pressed=true]{background:#e1f2ed;color:#20745e;border-color:#b7d9cf}#camera-controls{padding-bottom:20px;border-bottom:1px solid var(--line);margin-bottom:12px}#photo-controls .primary{width:100%;font-size:12px}#nasa-view{position:absolute;inset:0;background:#030303;z-index:2;display:flex;align-items:center;justify-content:center}#nasa-video{height:100%;width:100%;object-fit:contain}.nasa-credit{position:absolute;bottom:10px;left:14px;right:14px;display:flex;justify-content:space-between;gap:12px;background:#0009;padding:8px 10px;color:#b3b3c2;font-size:11px;line-height:1.5}.nasa-credit a{color:#d8dcdf}.field.photo .scene-heading,.field.photo .scene-caption{display:none}.stage.photo{grid-template-rows:44px 42px minmax(0,1fr) 38px 0 74px 28px}.stage.photo .launch-row{display:none}.stage.photo .stage-top{visibility:hidden}.field.orbit #field{cursor:grab}.field.orbit #field:active{cursor:grabbing}.legend>span:last-child{max-width:60%;font-size:11px}.stage .metrics small{line-height:1.3}.stage .metrics strong{font-variant-numeric:tabular-nums}.scene-heading #state{font-size:11px}.scene-caption{font-size:11px}#physics-controls h3{line-height:1.5}
@media(min-width:761px) and (max-height:700px){.stage{grid-template-rows:40px 36px minmax(0,1fr) 28px 50px 58px 24px}.stage.photo{grid-template-rows:40px 36px minmax(0,1fr) 32px 0 58px 24px}.view-tabs button{font-size:11px;padding:8px}}
@media(max-width:1100px){.view-tabs button{font-size:11px;padding:8px}.view-tabs{gap:0}}
@media(max-width:760px){.stage{height:790px;grid-template-rows:44px 42px minmax(0,1fr) 30px 56px 70px 28px}.stage.photo{height:700px;grid-template-rows:0 42px minmax(0,1fr) 38px 0 70px 28px}.view-tabs button{flex:0 0 auto;font-size:11px;padding:10px}.nasa-credit{flex-direction:column;gap:2px;font-size:11px}.mode-info{margin-top:4px}.legend>span:last-child{display:none}}

.stage.photo{grid-template-rows:0 42px minmax(0,1fr) 38px 0 74px 28px}.stage.photo .stage-top{display:none}.stage.photo .view-tabs{grid-row:2}.stage.photo .field{grid-row:3}.stage.photo .legend{grid-row:4;justify-content:flex-start}.stage.photo .legend>span:last-child{margin-left:0;max-width:100%}.stage.photo .metrics{grid-row:6}.stage.photo .status-bar{grid-row:7}#nasa-view{overflow:hidden}
@media(min-width:761px) and (max-height:700px){.stage.photo{grid-template-rows:0 36px minmax(0,1fr) 32px 0 58px 24px}}
@media(max-width:760px){.stage.photo{grid-template-rows:0 42px minmax(0,1fr) 38px 0 70px 28px}.stage.photo .legend>span{display:flex!important}}

/* End values of a slider stay on one line; a hint between them wraps instead. */
.range-label{gap:8px}.range-label>span:first-child,.range-label>span:last-child{white-space:nowrap}.range-label>span:nth-child(2):not(:last-child){text-align:center}