.reading-contents{border:1px solid var(--line);border-radius:8px;background:white;padding:18px 20px;display:flex;flex-wrap:wrap;gap:9px;margin-bottom:18px}.reading-contents>strong{flex-basis:100%;font-size:.9rem;color:var(--muted);margin-bottom:4px}.reading-contents button{border:0;background:#edf3f7;color:var(--navy);padding:9px 12px;border-radius:5px;font-size:.9rem;text-align:left;line-height:1.5}.reading-contents button:hover{background:#dfeef0}.reading-contents button span{color:var(--teal);margin-right:9px;font-weight:700}.reading-contents [data-reading-practice]{background:transparent;text-decoration:underline;text-underline-offset:3px}.diagram-key{display:flex;gap:10px 20px;flex-wrap:wrap;font-size:.875rem;color:var(--muted);margin:20px 0 30px}.diagram-key>span{display:flex;align-items:center;gap:7px}.diagram-key i{width:20px;height:7px;border:1px solid #728598;border-radius:2px}.key-solar{background:#f3c45b}.key-reflected{background:#f3f8ff}.key-absorbed{background:#72dadd}.key-infrared{background:#ffa296}.reading-section{margin:0 0 35px;padding-top:26px;border-top:1px solid var(--line)}.reading-section>.eyebrow{margin-bottom:10px}.reading-section h3{line-height:1.4;font-size:1.4rem;scroll-margin-top:22px}.reading-grid{display:block}.reading-copy{max-width:78ch}.reading-copy p{line-height:1.8;margin:0 0 18px}.reading-figure{margin:6px 0 22px;background:#102e50;color:#f3f8ff;border-radius:9px;overflow:hidden;width:100%;max-width:680px}.reading-figure svg{display:block;width:100%;height:auto;font-family:inherit}.reading-figure figcaption{padding:18px 22px 22px;border-top:1px solid #426078;line-height:1.65}.reading-figure figcaption strong{display:block;font-size:1rem;margin-bottom:7px}.reading-figure figcaption>span{display:block;color:#c2d7e6;font-size:.9rem}.equation-steps{max-width:850px;border-left:3px solid var(--teal);padding:19px 23px;background:#edf6f6;margin:20px 0}.equation-steps h4{line-height:1.5}.equation-steps ol{padding-left:24px;margin:12px 0 0;line-height:1.8;font-variant-numeric:tabular-nums}.equation-steps li{padding-left:6px;overflow-wrap:anywhere}.equation-steps li::marker{color:#607f88;font-size:.85rem}.reading-key{border-left:3px solid var(--gold);background:#fff9eb;padding:14px 18px;line-height:1.75;max-width:850px}.reading-key strong{display:block;color:#78501b;font-size:.9rem}.reading-check{background:white;border:1px solid var(--line);border-radius:8px;padding:22px;margin:24px 0;line-height:1.75}.reading-check summary{cursor:pointer;color:var(--teal);font-weight:600}.reading-check h3{font-size:1.16rem}.reading-check details p{background:#edf7f6;padding:14px 18px}.gas-table{margin:22px 0;max-width:900px}.gas-table table{width:100%;border-collapse:collapse;background:white;font-size:.95rem;table-layout:fixed}.gas-table caption{text-align:left;font-weight:650;margin-bottom:15px;line-height:1.5}.gas-table th,.gas-table td{text-align:left;vertical-align:top;padding:15px;border:1px solid var(--line);line-height:1.7;overflow-wrap:anywhere}.gas-table thead{background:#e8f0f5}.gas-table tbody th{font-weight:600}.reading-experiment{margin:30px 0;border:1px solid #bfd1df;border-radius:9px;background:white}.reading-experiment>summary{padding:19px 22px;font-size:1.1rem;font-weight:650;color:var(--navy);cursor:pointer}.reading-experiment>summary span{display:block;font-weight:400;font-size:.875rem;line-height:1.6;color:var(--muted);margin:7px 0 0 16px}.experiment-only{border:0;border-top:1px solid var(--line);border-radius:0 0 9px 9px;margin:0;box-shadow:none}.emission-comparison{padding:22px;background:#102e50;color:#f3f8ff;display:grid;gap:26px}.emission-comparison>div>strong,.emission-comparison>div>span{display:block;line-height:1.6}.emission-track{height:24px;margin:12px 0;background:#24445f}.emission-track i{height:100%;display:block;background:#ffa296}.lesson-meta{flex-wrap:wrap}.next-lesson a{line-height:1.6}#exam-practice{scroll-margin-top:22px}#lesson:focus,#exam-practice:focus,.reading-section h3:focus{outline:none}
@media(min-width:1250px){.reading-grid.with-figure{display:grid;grid-template-columns:minmax(0,1fr) minmax(370px,.95fr);gap:28px;align-items:start}.reading-figure{margin-top:0}}
@media(max-width:720px){.reading-contents{padding:15px;display:grid;gap:6px}.reading-contents>strong{margin-bottom:6px}.reading-contents button{width:100%}.reading-section{padding-top:23px}.reading-section h3{font-size:1.25rem}.reading-figure figcaption{padding:15px 17px}.equation-steps{padding:16px}.equation-steps ol{font-size:.95rem;padding-left:20px}.diagram-key{gap:12px;font-size:.875rem}.gas-table th,.gas-table td{padding:8px;font-size:.875rem}.gas-table thead th:first-child{width:26%}.reading-experiment>summary{padding:18px}.reading-copy p{line-height:1.75}.reading-check{padding:19px}}
@media(prefers-reduced-motion:reduce){.reading *,.experiment-only *{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

/* Scientific illustrations need enough space for their geometry and labels. */
.reading-grid.with-figure:has(.scientific-figure){display:block}
.reading-figure.scientific-figure{max-width:960px;margin:24px 0;background:#fff;color:#183149;border:1px solid #dce4ed;border-radius:4px}
.scientific-figure img{display:block;width:100%;height:auto;background:white}
.scientific-figure figcaption{border-top:1px solid #e0e7ee;padding:20px 24px}
.scientific-figure figcaption>span{color:#475f73}
.diagram-key .key-solar{background:#e5a421}.diagram-key .key-reflected{background:#357aa8}.diagram-key .key-absorbed{background:#218d91}.diagram-key .key-infrared{background:#bc5d45}
.figure-open{display:inline-block;margin-top:12px;font-size:.9rem;text-underline-offset:3px;line-height:1.7}
@media(max-width:720px){.scientific-figure figcaption{padding:16px}.figure-open{padding:5px 0}}

/* Exam application follows the teaching and has its own visible card. */
.exam-focus{border:1px solid #ddc99e;border-left:4px solid #b5852c;background:#fffaf0;border-radius:6px;padding:24px 28px;margin-top:34px}
.exam-focus h3{color:#795516}
.exam-focus .exam-notes h4{color:var(--navy)}
.exam-focus .exam-notes{font-size:1rem}
.exam-focus ul{margin-bottom:0}
@media(max-width:720px){.exam-focus{padding:20px}.exam-focus .exam-notes{gap:22px}}

/* Locally hosted LaTeX notation shares the lesson colour and stays selectable. */
.math-inline{white-space:normal}.math-inline .katex{font-size:1.06em;line-height:1.5}
.math-display{display:block;max-width:100%;overflow-x:auto;overflow-y:hidden;padding:.2rem 0}
.math-display .katex-display{margin:.55rem 0;text-align:left}
.math-display .katex-display>.katex{text-align:left;font-size:1.1em}
.equation-context{display:block;color:var(--muted,#536477);font-size:.95rem;margin-top:.5rem}
.equation-steps li{padding:.2rem 0;overflow-wrap:normal}.equation-steps ol{display:block}
.reading-copy p,.feedback p,.worked li{line-height:1.85}
@media(max-width:600px){.math-display .katex-display>.katex{font-size:1em}.equation-steps{padding:18px 16px}.equation-steps ol{padding-left:22px}}