._lesson_d7mlb_1{max-width:1000px;color:var(--ink);margin:0 auto}._section_d7mlb_2{border-top:1px solid var(--border);padding:48px 0;scroll-margin-top:90px}._section_d7mlb_2:first-child{border-top:0;padding-top:12px}._section_d7mlb_2 h2{margin:0 0 25px;font-size:clamp(23px,3vw,34px);font-weight:600;line-height:1.4}._section_d7mlb_2 h3{margin:28px 0 15px;font-size:20px;font-weight:600}._prose_d7mlb_6{max-width:810px;margin:17px 0;font-size:17px;line-height:1.95}._intro_d7mlb_7{max-width:850px;margin:20px 0 30px;font-size:20px;line-height:1.85}._experiment_d7mlb_8{border:1px solid var(--border);background:var(--paper,var(--plot));border-radius:14px;margin:30px 0;overflow:hidden}._experiment_d7mlb_8 h3{margin:0;padding:22px 25px 0}._experiment_d7mlb_8>p{margin-left:25px;margin-right:25px}._canvas_d7mlb_11{background:var(--soft);padding:15px;position:relative}._canvas_d7mlb_11 svg{width:100%;height:auto;max-height:450px;display:block}._canvas_d7mlb_11 svg text{fill:var(--ink);font-family:inherit;font-size:17px}._controls_d7mlb_14{border-top:1px solid var(--border);flex-wrap:wrap;align-items:center;gap:12px;padding:18px 25px;display:flex}._controls_d7mlb_14 button,._choices_d7mlb_15 button{border:1px solid var(--border);color:var(--ink);background:var(--plot);min-height:44px;font:inherit;cursor:pointer;border-radius:7px;padding:10px 15px}._controls_d7mlb_14 button:disabled{opacity:.4;cursor:default}._controls_d7mlb_14 button[aria-pressed=true],._choices_d7mlb_15 button[aria-pressed=true]{background:color-mix(in srgb, #317aa6 13%, var(--plot));border-color:#317aa6}._slider_d7mlb_18{flex:235px;gap:9px;min-width:0;display:grid}._slider_d7mlb_18>span{justify-content:space-between;align-items:center;gap:10px;font-size:14px;display:flex}._slider_d7mlb_18 input{accent-color:#337ca6;width:100%;min-height:24px}._readout_d7mlb_21{background:var(--soft);padding:16px 25px;font-size:16px;line-height:1.8;overflow-x:auto}._formula_d7mlb_22{background:var(--soft);border-left:3px solid #337ca6;margin:20px 0;padding:15px 20px;overflow-x:auto}._note_d7mlb_23{border-left:3px solid #b78335;margin:24px 0;padding:16px 22px;line-height:1.85}._choices_d7mlb_15{flex-wrap:wrap;gap:10px;margin:18px 0;display:flex}._answer_d7mlb_25{border-bottom:1px solid var(--border);margin:15px 0 25px;padding-bottom:20px}._answer_d7mlb_25 summary{cursor:pointer;padding:10px 0;line-height:1.7}._sources_d7mlb_27{gap:10px;padding-left:20px;font-size:14px;line-height:1.8;display:grid}._sources_d7mlb_27 a{text-underline-offset:3px;text-decoration:underline}._steps_d7mlb_29{gap:12px;padding:0;list-style:none;display:grid}._steps_d7mlb_29 li{border-left:2px solid var(--border);padding:16px 20px;line-height:1.85}._steps_d7mlb_29 li[data-current=true]{background:var(--soft);border-color:#337ca6}._clockPair_d7mlb_32{grid-template-columns:repeat(2,minmax(0,1fr));gap:30px;padding:25px;display:grid}._clockFace_d7mlb_33{border:3px solid #337ca6;border-radius:50%;width:130px;height:130px;margin:15px auto;position:relative}._hand_d7mlb_34{transform-origin:50% 100%;background:#337ca6;width:3px;height:49px;position:absolute;top:15px;left:62px}._clockLabel_d7mlb_35{text-align:center;line-height:1.8}@media (max-width:600px){._canvas_d7mlb_11 svg text{font-size:26px}._section_d7mlb_2{padding:32px 0}._prose_d7mlb_6{font-size:16px}._intro_d7mlb_7{font-size:18px}._experiment_d7mlb_8 h3{padding:18px 16px 0}._controls_d7mlb_14,._readout_d7mlb_21{padding:16px}._canvas_d7mlb_11{padding:5px}._experiment_d7mlb_8>p{margin-left:16px;margin-right:16px}._clockPair_d7mlb_32{gap:12px;padding:15px}._formula_d7mlb_22{padding:10px}}._playback_d7mlb_37{min-width:0;color:var(--muted);flex:100%;align-items:center;gap:10px;font-size:13px;display:flex}._playback_d7mlb_37 input{min-width:60px;accent-color:var(--primary);flex:1}._playback_d7mlb_37 output{text-align:right;font-variant-numeric:tabular-nums;min-width:3.5em}._lesson_16aa3_1{color:var(--ink,#25352e);font-size:1.04rem;line-height:1.85}._lesson_16aa3_1 p{margin:1rem 0}._lesson_16aa3_1 h2{letter-spacing:-.025em;margin:0 0 1.4rem;font-size:clamp(1.45rem,3vw,2rem);line-height:1.35}._lesson_16aa3_1 h3{margin:1.8rem 0 .65rem;font-size:1.15rem}._intro_16aa3_5{max-width:76ch;font-size:1.15rem}._nav_16aa3_6{flex-wrap:wrap;gap:.45rem .9rem;margin:2rem 0 3.5rem;display:flex}._nav_16aa3_6 a{color:var(--accent,#397c69);text-underline-offset:4px;font-size:.9rem;text-decoration:underline}._chapter_16aa3_8{border-top:1px solid color-mix(in srgb, var(--ink,#25352e) 18%, transparent);padding:2.7rem 0;scroll-margin-top:90px}._lead_16aa3_9{color:var(--muted,#59675f)}._lab_16aa3_10{background:var(--plot,#f4f5ef);border:1px solid color-mix(in srgb, var(--ink,#25352e) 15%, transparent);border-radius:14px;margin:1.7rem 0;padding:clamp(.85rem,3vw,1.6rem)}._lab_16aa3_10 h3{margin:0 0 .7rem}._lab_16aa3_10 p{margin:.65rem 0 1rem}._plot_16aa3_13{background:var(--soft,#fffdf6);border-radius:8px;overflow:hidden}._svg_16aa3_14{width:100%;min-width:0;height:auto;color:var(--ink,#25352e);display:block}._svg_16aa3_14 text{fill:currentColor;font-family:inherit;font-size:15px}._controls_16aa3_16{flex-wrap:wrap;align-items:center;gap:.65rem;margin:1.1rem 0;display:flex}._controls_16aa3_16 button,._stepper_16aa3_17 button{border:1px solid color-mix(in srgb, var(--ink,#25352e) 30%, transparent);background:var(--soft,#fffdf6);color:var(--ink,#25352e);font:inherit;cursor:pointer;border-radius:7px;padding:.6rem .9rem;font-size:.88rem}._controls_16aa3_16 button[aria-pressed=true]{background:var(--accent,#397c69);color:#fff}:is(._controls_16aa3_16 button:focus-visible,._stepper_16aa3_17 button:focus-visible,._range_16aa3_19 input:focus-visible,._lesson_16aa3_1 summary:focus-visible){outline-offset:3px;outline:3px solid #cc8849}._controls_16aa3_16 button:disabled,._stepper_16aa3_17 button:disabled{opacity:.4;cursor:default}._ranges_16aa3_21{grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:1rem 1.7rem;display:grid}._range_16aa3_19{gap:.4rem;font-size:.9rem;display:grid}._range_16aa3_19>span{justify-content:space-between;align-items:baseline;gap:1rem;display:flex}._range_16aa3_19 input{width:100%;accent-color:var(--accent,#397c69)}._readouts_16aa3_25{grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:.6rem 1rem;margin:1rem 0;display:grid}._readouts_16aa3_25 div{border-top:2px solid color-mix(in srgb, var(--accent,#397c69) 45%, transparent);padding-top:.55rem}._readouts_16aa3_25 dt{color:var(--muted,#59675f);font-size:.8rem}._readouts_16aa3_25 dd{margin:.15rem 0 0;font-size:1.05rem;overflow-x:auto}._formula_16aa3_29{margin:.8rem 0;padding:.4rem .2rem;overflow-x:auto}._note_16aa3_30{border-left:3px solid var(--warm,#be7748);background:color-mix(in srgb, var(--warm,#be7748) 7%, transparent);padding:.7rem 1rem}._stepper_16aa3_17{flex-wrap:wrap;align-items:center;gap:.65rem;margin:1rem 0;display:flex}._stepper_16aa3_17 output{text-align:center;min-width:8rem;font-size:.9rem}._check_16aa3_33{border-bottom:1px solid color-mix(in srgb, var(--ink,#25352e) 15%, transparent);margin:1.4rem 0;padding-bottom:1.2rem}._check_16aa3_33 summary{cursor:pointer;color:var(--accent,#397c69);font-weight:600}._sources_16aa3_35{font-size:.9rem}._sources_16aa3_35 a{color:var(--accent,#397c69)}._legend_16aa3_37{flex-wrap:wrap;gap:1rem;font-size:.86rem;display:flex}._legend_16aa3_37 span{align-items:center;gap:.4rem;display:inline-flex}._legend_16aa3_37 i{border-radius:50%;width:.8rem;height:.8rem;display:inline-block}@media (max-width:600px){._lesson_16aa3_1{font-size:1rem}._chapter_16aa3_8{padding:2rem 0}._ranges_16aa3_21{grid-template-columns:1fr}._svg_16aa3_14 text{font-size:24px}}._transport_16aa3_41{border-block:1px solid var(--border);grid-template-columns:auto minmax(210px,1fr);align-items:center;gap:1.25rem;margin:1.1rem 0;padding:.5rem 0 1rem;display:grid}._transport_16aa3_41 ._controls_16aa3_16{margin:.5rem 0}._transport_16aa3_41 output{color:var(--muted);font-size:.85rem}._action_16aa3_44{border:1px solid var(--border);background:var(--soft);color:var(--ink);font:inherit;cursor:pointer;border-radius:6px;padding:.65rem .9rem}._graph_16aa3_45{border-block:1px solid var(--border);background:var(--soft);min-width:0;margin:1.4rem 0;padding:1rem}._graph_16aa3_45 figcaption{margin-bottom:.65rem;font-size:1rem;font-weight:600}._graph_16aa3_45 svg{width:100%;height:auto;color:var(--ink);display:block}._graphScale_16aa3_48{font:500 .8rem/1.5 var(--font-sans);color:var(--muted);justify-content:space-between;gap:.5rem;display:flex}._graphPair_16aa3_49{grid-template-columns:repeat(2,minmax(0,1fr));gap:1.25rem;display:grid}._decisions_16aa3_50{grid-template-columns:repeat(3,minmax(0,1fr));gap:1rem;padding:0;list-style:none;display:grid}._decisions_16aa3_50 li{border-top:2px solid var(--border);padding-top:.75rem}._decisions_16aa3_50 button{text-align:left;font:600 .95rem/1.5 var(--font-sans);color:var(--ink);background:0 0;border:0;border-bottom:2px solid #0000;padding:.35rem 0}._decisions_16aa3_50 button[aria-pressed=true]{color:var(--accent);border-bottom-color:var(--accent)}._decisions_16aa3_50 p{font-size:.92rem;line-height:1.8}._readouts_16aa3_25 div:nth-child(2) dd{color:#b26430}@media (max-width:760px){._transport_16aa3_41,._graphPair_16aa3_49,._decisions_16aa3_50{grid-template-columns:1fr}._transport_16aa3_41{gap:.5rem}._lab_16aa3_10{padding:.9rem}._graph_16aa3_45{padding:.6rem 0}._readouts_16aa3_25{grid-template-columns:repeat(2,minmax(0,1fr))}._readouts_16aa3_25 dd{font-size:.98rem}._decisions_16aa3_50{gap:.6rem}}._lesson_bkibo_1{color:var(--ink,#edf1f7);font-size:1.03rem;line-height:1.9}._lesson_bkibo_1 p{max-width:78ch;margin:1.1rem 0}._lesson_bkibo_1 h2{letter-spacing:-.025em;margin:0 0 1.4rem;font-size:clamp(1.45rem,3vw,2rem);font-weight:650;line-height:1.4}._lesson_bkibo_1 h3{margin:0 0 1rem;font-size:1.15rem;line-height:1.5}._section_bkibo_5{margin:4.6rem 0;scroll-margin-top:6rem}._intro_bkibo_6{max-width:78ch;font-size:1.12rem}._lab_bkibo_7{background:var(--soft,#15202b);border:1px solid var(--border,#394652);border-radius:18px;margin:2rem 0;padding:clamp(16px,3.5vw,30px)}._lab_bkibo_7 p{font-size:.97rem}._choices_bkibo_9,._controls_bkibo_9,._legend_bkibo_9,._breadcrumb_bkibo_9{flex-wrap:wrap;align-items:center;gap:.65rem;display:flex}._controls_bkibo_9{margin-top:.9rem}._steps_bkibo_11{margin:1.25rem 0}._lesson_bkibo_1 button{border:1px solid var(--border,#52616c);color:inherit;background:var(--plot,#0b1520);cursor:pointer;font:inherit;border-radius:8px;min-height:42px;padding:.55rem .85rem;font-size:.9rem;line-height:1.5}._lesson_bkibo_1 button[aria-pressed=true]{border-color:var(--accent,#65bfc4);box-shadow:inset 0 0 0 1px var(--accent,#65bfc4);background:color-mix(in srgb, var(--accent,#65bfc4) 15%, var(--plot,#0b1520))}:is(._lesson_bkibo_1 button:focus-visible,._lesson_bkibo_1 input:focus-visible){outline:3px solid var(--accent,#65bfc4);outline-offset:3px}._lesson_bkibo_1 button:disabled{opacity:.42;cursor:default}._formula_bkibo_16{padding:.7rem 0;font-size:1.03rem;overflow:auto hidden}._diagram_bkibo_17{width:100%;min-width:0;height:auto;color:var(--ink,#edf1f7);background:var(--plot,#0b1520);border-radius:12px;margin:1rem 0;display:block}._diagram_bkibo_17 text{fill:currentColor;font-family:inherit;font-size:17px}._caption_bkibo_19{min-height:4rem;padding:.7rem 0}._legend_bkibo_9{margin:.8rem 0;font-size:.9rem}._legend_bkibo_9 span{align-items:center;gap:.4rem;display:inline-flex}._dot_bkibo_22{background:var(--particle-colour);border-radius:50%;width:.8rem;height:.8rem;display:inline-block}._breadcrumb_bkibo_9{color:var(--muted,#a8b2c0);font-size:.86rem}._breadcrumb_bkibo_9 strong{color:var(--ink,#edf1f7)}._compare_bkibo_25{grid-template-columns:1fr 1fr;gap:1rem;margin:1rem 0;display:grid}._board_bkibo_26{border:1px solid var(--border,#435261);background:var(--plot,#0b1520);border-radius:12px;min-width:0;padding:1.2rem}._board_bkibo_26 h4{margin:0 0 .8rem;font-weight:550}._quarks_bkibo_28{justify-content:center;gap:.7rem;padding:1.2rem .2rem;display:flex}._particle_bkibo_29{color:#0d1820;background:var(--particle-colour);border:2px solid #0000;border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:54px;height:54px;font-size:1.2rem;display:inline-flex}._selected_bkibo_30{outline:3px solid var(--warm,#f1c486);outline-offset:5px}._outputs_bkibo_31{flex-wrap:wrap;align-items:center;gap:1rem;min-height:70px;display:flex}._output_bkibo_31{align-items:center;gap:.5rem;display:inline-flex}._note_bkibo_33{border-left:3px solid var(--accent,#65bfc4);color:var(--muted,#a8b2c0);padding-left:1rem}._readouts_bkibo_34{flex-wrap:wrap;gap:1rem 2rem;margin:1rem 0;display:flex}._readouts_bkibo_34 div{min-width:115px}._readouts_bkibo_34 dt{color:var(--muted,#a8b2c0);font-size:.85rem}._readouts_bkibo_34 dd{margin:.25rem 0 0;font-size:1.1rem}._range_bkibo_38{gap:.5rem;margin:1.4rem 0;display:grid}._range_bkibo_38 input{width:100%;max-width:520px;accent-color:var(--accent,#65bfc4)}._energy_bkibo_40{background:#273645;border-radius:7px;width:100%;height:46px;margin-top:1rem;display:flex;overflow:hidden}._energy_bkibo_40>span{height:100%;transition:width .18s}._rule_bkibo_42{border-left:3px solid var(--warm,#f1c486);background:var(--plot,#0b1520);margin:1rem 0;padding:1rem}._samples_bkibo_43{grid-template-columns:repeat(9,minmax(0,1fr));align-items:end;gap:4px;height:190px;padding:10px 0 0;display:grid}._samples_bkibo_43 button{background:0 0;border-radius:6px;flex-direction:column;justify-content:flex-end;align-items:stretch;min-width:0;height:100%;padding:5px 0;display:flex}._sampleColumn_bkibo_45{flex-direction:column;justify-content:flex-end;height:130px;margin:0 5px;display:flex}._sampleBase_bkibo_46{background:#5f9acb;height:60px;display:block}._sampleExtra_bkibo_47{background:#e8b568;display:block}._sampleLabel_bkibo_48{margin-top:.4rem;font-size:.72rem}._massbar_bkibo_49{background:#304151;border-radius:4px;height:24px;margin:1rem 0;overflow:hidden}._massbar_bkibo_49 span{background:#9fc8a7;height:100%;display:block}._exercise_bkibo_51{border-bottom:1px solid var(--border,#435261);padding:1.1rem 0}._sources_bkibo_52{margin:4rem 0 1rem;font-size:.9rem}._sources_bkibo_52 li{margin:.6rem 0}._sources_bkibo_52 a{color:var(--accent,#7dc5c9);text-underline-offset:3px;text-decoration:underline}._coefficients_bkibo_55{grid-template-columns:1fr 1fr;gap:1rem;display:grid}._coefficient_bkibo_55{background:var(--plot,#0b1520);border:1px solid var(--border,#435261);border-radius:8px;padding:1rem}@media (max-width:560px){._compare_bkibo_25,._coefficients_bkibo_55{grid-template-columns:1fr}._lesson_bkibo_1{font-size:1rem}._lab_bkibo_7{margin-left:-3px;margin-right:-3px}._section_bkibo_5{margin-top:3.5rem}._sampleColumn_bkibo_45{margin:0 2px}._choices_bkibo_9 button{padding:.4rem .55rem;font-size:.82rem}._diagram_bkibo_17 text{font-size:32px}}@media (prefers-reduced-motion:reduce){._energy_bkibo_40>span{transition:none}}._lesson_1iyto_1{--accent:#287a75;--warm:#af5b30;--plot:#fff;--soft:#f3f6f5;--ink:#26363b;--muted:#596b72;color:var(--ink);min-width:0;padding-top:36px;padding-bottom:64px}.dark ._lesson_1iyto_1{--accent:#77ccbe;--warm:#f0ae79;--plot:#151d22;--soft:#1b272e;--ink:#e2ecee;--muted:#afc1c9}._heading_1iyto_21{margin-bottom:24px}._back_1iyto_22{color:var(--muted);padding:8px 0;font-size:14px;display:inline-block}._back_1iyto_22:hover{color:var(--ink)}._heading_1iyto_21 h1{letter-spacing:-.025em;max-width:29ch;margin-top:15px;font-size:clamp(27px,3.2vw,40px);font-weight:500;line-height:1.35}._lesson_1iyto_1 button,._lesson_1iyto_1 input,._lesson_1iyto_1 select{font:inherit}._lesson_1iyto_1 button,._lesson_1iyto_1 input[type=range],._lesson_1iyto_1 select{touch-action:manipulation}:is(._lesson_1iyto_1 button:focus-visible,._lesson_1iyto_1 input:focus-visible,._lesson_1iyto_1 select:focus-visible,._lesson_1iyto_1 a:focus-visible,._lesson_1iyto_1 summary:focus-visible){outline:2px solid var(--accent);outline-offset:4px}._lesson_1iyto_1 .math-block{max-width:100%}@media (max-width:600px){._lesson_1iyto_1{padding-top:24px}._heading_1iyto_21 h1{max-width:100%}}