:root{--navy:#073d78;--deep:#08294e;--blue:#1469c4;--pale:#edf5ff;--line:#cbdcf0;--ink:#162d48;--muted:#50647a;--paper:#fff;--radius:18px;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--ink);background:#f4f8fd;color-scheme:light}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;font-size:17px;line-height:1.7}a{color:#0756a5;text-underline-offset:4px}a:hover{text-decoration-thickness:2px}button,input,select,textarea{font:inherit}button,.button{border:1px solid var(--blue);background:var(--navy);color:#fff;border-radius:10px;padding:12px 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.55em}h2{font-size:clamp(1.7rem,2.7vw,2.4rem);margin-top:1.6em}h3{font-size:1.35rem;margin-top:1.8em}p{margin:0 0 1.1em}small,.small{font-size:.88rem;line-height:1.6;color:var(--muted)}.eyebrow{font-size:.8rem;font-weight:800;letter-spacing:.12em;text-transform:uppercase;color:#2263a8;margin-bottom:12px}.skip{position:fixed;top:-100px;z-index:99;background:white;padding:15px}.skip:focus{top:8px}.topbar{height:82px;position:sticky;top:0;z-index:20;background:#ffffffed;backdrop-filter:blur(14px);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:22px;padding:14px 30px}.brand{display:flex;align-items:center}.brand img{height:42px;width:145px;object-fit:contain}.top-title{border-left:1px solid var(--line);padding-left:22px;font-size:.95rem;font-weight:700}.top-title span{display:block;color:var(--muted);font-size:.8rem}.othm{margin-left:auto;width:100px;height:40px;object-fit:contain}.campus-link{font-size:.9rem}.layout{display:grid;grid-template-columns:270px minmax(0,1fr);max-width:1600px;margin:auto}.sidebar{border-right:1px solid var(--line);padding:26px 20px;position:sticky;top:82px;align-self:start;max-height:calc(100vh - 82px);overflow:auto;background:#f4f8fd}.sidebar nav a{display:flex;gap:10px;align-items:center;padding:10px 12px;border-radius:9px;margin:4px 0;text-decoration:none;font-size:.91rem;font-weight:650;line-height:1.45}.sidebar nav a span{color:#2770b8;font-variant-numeric:tabular-nums;min-width:26px}.sidebar nav a[aria-current=page]{background:var(--navy);color:white}.sidebar nav a[aria-current=page] span,.sidebar nav a[aria-current=page] small{color:white}.sidebar .eyebrow{margin:20px 12px 5px;font-size:.73rem}.sidebar summary{font-weight:750;cursor:pointer}.sidebar nav small{margin-left:auto}.progress-box{border-top:1px solid var(--line);padding-top:18px;margin-top:20px;font-size:.85rem}.progress-box progress{display:block;width:100%;height:8px;accent-color:var(--blue);margin:10px 0}.glossary{margin:24px 0;padding-top:18px;border-top:1px solid var(--line)}.glossary label{font-size:.85rem;margin-top:12px}.glossary input{font-size:.85rem}.term{border-bottom:1px solid var(--line);padding:10px 0;font-size:.88rem}.term strong{display:block;color:var(--navy)}main{padding:34px clamp(24px,4vw,62px) 20px;min-width:0}.view[hidden]{display:none!important}.hero{background:var(--navy);border-radius:24px;overflow:hidden;display:grid;grid-template-columns:1.15fr 1fr;min-height:400px;box-shadow:0 16px 40px #073d7814}.hero-copy{padding:36px;align-self:center}.hero h1,.hero p,.hero .eyebrow{color:#fff}.hero h1{font-size:clamp(2.1rem,3.2vw,3.4rem)}.hero img{height:100%;object-fit:cover;width:100%;min-width:0}.hero-facts{display:flex;gap:8px;flex-wrap:wrap;margin:20px 0}.hero-facts span{border:1px solid #ffffff70;border-radius:100px;padding:5px 11px;font-size:.8rem;color:white}.light{background:white;color:var(--navy);border-color:white}.light:hover{background:#e8f3ff}.intro-grid{display:grid;grid-template-columns:1.4fr 1fr;gap:28px;margin:40px 0}.intro-grid h2{margin-top:0}.book-card{border:1px solid var(--line);border-top:5px solid var(--blue);padding:24px;border-radius:16px;background:white;align-self:start}.book-card h3{margin-top:10px}.book-card .button{font-size:.92rem}.section-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.section-card{display:block;padding:23px;background:white;border:1px solid var(--line);border-radius:var(--radius);text-decoration:none;font-size:.95rem}.section-card h3{margin:.2em 0 1em}.section-card:first-child{background:var(--navy);color:white}.section-card:first-child h3,.section-card:first-child .eyebrow{color:white}.section-card.locked{background:#f8fbff}.section-card strong{font-size:.92rem}.section-card .eyebrow{font-size:.73rem}.map-block{border:1px solid var(--line);border-radius:12px;background:white;margin:15px 0;overflow:hidden}.map-block summary{padding:17px 20px;font-weight:700;cursor:pointer;color:var(--navy)}.map-block>.small{padding:0 20px}.table-scroll{overflow-x:auto;margin:20px 0;border:1px solid var(--line);border-radius:12px;background:white}table{border-collapse:collapse;width:100%;font-size:.9rem;line-height:1.55}th{background:var(--navy);color:white;text-align:left}th,td{padding:15px;vertical-align:top;border-bottom:1px solid var(--line)}tbody tr:nth-child(even){background:#f5f9fe}.requirements{min-width:770px}.requirements td:first-child{width:20%}.requirements td:nth-child(2){width:41%}.requirements ul,.requirements ol{padding-left:18px;margin:0}.requirements li{margin:0 0 13px}.requirements ol{list-style:none;padding:0}.note{border-left:5px solid var(--blue);background:#eaf3fe;border-radius:0 12px 12px 0;padding:22px;margin:25px 0}.note strong{color:var(--navy)}.author{display:grid;grid-template-columns:220px 1fr;gap:30px;align-items:center;margin:50px 0}.author img{border-radius:20px}.author h2{margin-top:0;font-size:1.8rem}.lesson{max-width:1000px;margin:auto}.lesson-head{border-left:6px solid var(--blue);padding:16px 0 16px 28px;margin-bottom:30px}.official{padding:20px;background:#e7f1ff;border:1px solid var(--line);border-radius:12px;font-size:1rem}.topic-index{padding:18px 22px;background:white;border:1px solid var(--line);border-radius:16px;margin-bottom:35px}.topic-index summary{font-weight:750;cursor:pointer}.topic-index nav{display:grid;grid-template-columns:1fr 1fr;gap:8px 20px;margin-top:14px}.topic-index a{font-size:.93rem;display:flex;gap:10px;text-decoration:none}.topic-index a span{font-weight:750;color:var(--navy);min-width:34px}.prose{max-width:850px;margin:auto}.prose h3{padding-top:18px;border-top:1px solid var(--line);margin-top:34px;font-size:1.55rem}.refs{white-space:nowrap;font-size:.8rem}.scene{margin:30px 0 40px;border:1px solid var(--line);border-radius:18px;overflow:hidden;background:white}.scene img{display:block;width:100%;aspect-ratio:3/2;object-fit:cover;max-height:420px}.scene figcaption{padding:20px;font-size:.94rem;line-height:1.6}.scene figcaption strong{display:block}.observe{display:block;margin:9px 0;color:#0755a1}.scene small{display:block;font-size:.8rem}.practice{margin-top:50px;border:2px solid #9cbee4;border-radius:22px;padding:26px;background:#edf5ff}.practice h2{margin-top:0}.tool,.question{padding:23px;background:white;border:1px solid var(--line);border-radius:15px;margin:20px 0}.tool h3,.tool h2{margin-top:0}.tool-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.tool fieldset,.question fieldset{border:0;margin:0;padding:0;min-width:0}.question legend{font-weight:750;font-size:1.04rem;margin-bottom:12px}.option{border:1px solid var(--line);padding:10px 12px;border-radius:8px;margin:8px 0;cursor:pointer;font-weight:450;display:flex;align-items:baseline;gap:5px}.option:has(input:checked){background:var(--pale);border-color:var(--blue)}.feedback,.result{padding:15px;background:#e9f3ff;border-left:4px solid var(--blue);margin-top:16px;border-radius:5px;color:#17395b}.feedback:empty,.result:empty{display:none}.result strong{display:block}.tool button,.reflection button{margin:7px 7px 0 0}.reflection{margin:24px 0}.reflection summary{font-weight:700;cursor:pointer}.reflection textarea{margin-top:15px}.lesson-next{display:flex;align-items:center;justify-content:space-between;gap:20px;margin:35px 0}.footer{margin-top:70px;border-top:1px solid var(--line);padding:30px 0;font-size:.85rem;color:var(--muted)}.footer p{max-width:760px}.toast{position:fixed;bottom:20px;right:20px;background:var(--deep);color:white;max-width:350px;border-radius:12px;padding:0;z-index:50}.toast:not(:empty){padding:16px 22px}.check-label{font-weight:450;margin:8px 0}.mark-read[aria-pressed=true]{background:#174e5a}.live-value{font-size:1.8rem;font-weight:800;color:var(--navy)}
@media(max-width:1150px){.layout{grid-template-columns:235px minmax(0,1fr)}.sidebar{padding:20px 13px}.hero{grid-template-columns:1fr}.hero img{max-height:300px}.intro-grid{grid-template-columns:1fr}.section-grid{grid-template-columns:1fr 1fr}}
@media(max-width:760px){body{font-size:16px}.topbar{height:70px;padding:10px 16px;gap:12px}.brand img{width:110px;height:35px}.top-title{padding-left:12px;font-size:.82rem}.othm{width:72px}.campus-link{display:none}.layout{display:block}.sidebar{position:relative;top:auto;max-height:none;border-right:0;border-bottom:1px solid var(--line);padding:15px 20px}.sidebar nav{display:grid;grid-template-columns:1fr 1fr}.sidebar nav .eyebrow{grid-column:1/-1}.sidebar .progress-box,.sidebar>.small{display:none}main{padding:24px 18px}.hero-copy{padding:28px}.hero h1{font-size:2.2rem}.hero img{height:240px}.section-grid{grid-template-columns:1fr}.author{grid-template-columns:1fr}.author img{max-width:280px}.topic-index nav{grid-template-columns:1fr}.lesson-head{padding-left:18px}.tool-grid{grid-template-columns:1fr}.practice{padding:18px}.tool,.question{padding:17px}.lesson-next{align-items:stretch;flex-direction:column}.scene figcaption{padding:16px}h1{font-size:2.3rem}.topbar .brand{min-width:90px}.requirements{min-width:740px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{animation:none!important;transition:none!important}}
@media print{.topbar,.sidebar,.toast,.lesson-next,.mark-read{display:none}main{padding:0}.layout{display:block}.view[hidden]{display:none!important}.scene{break-inside:avoid}.tool,.question{break-inside:avoid}body{background:white;font-size:11pt}h1{font-size:25pt}button{display:none}a{color:inherit}.hero{box-shadow:none}p{orphans:3;widows:3}}

/* Unit 5 editorial refresh: a photo-to-white opening and a quieter reading surface. */
.hero{position:relative;display:block;min-height:440px;background:#fff;border:1px solid var(--line);border-radius:20px;isolation:isolate;box-shadow:0 14px 38px #073d780c}
.hero-copy{position:relative;z-index:2;width:68%;padding:44px 36px 42px 42px}
.hero>img{position:absolute;inset:0 0 0 auto;width:65%;height:100%;min-height:440px;max-height:none;object-fit:cover;object-position:62% center;mask-image:linear-gradient(to right,transparent 0%,#000 72%);-webkit-mask-image:linear-gradient(to right,transparent 0%,#000 72%)}
.hero h1{color:var(--navy);font-size:clamp(2.1rem,3.1vw,3.35rem);line-height:1.13;letter-spacing:-.045em}
.hero p{color:var(--ink);max-width:34ch}.hero .eyebrow{color:#155caa}.hero-facts{max-width:420px}.hero-facts span{color:var(--navy);border-color:#bdd2e9;background:#ffffffeb;font-size:.875rem}.hero .button{background:var(--navy);color:white;border-color:var(--navy)}.hero .button:hover{background:#0a549a}
.author{padding:28px;gap:35px;background:var(--navy);border-radius:20px;grid-template-columns:210px minmax(0,1fr);overflow:hidden}.author img{width:210px;height:auto;max-width:100%;border-radius:12px;display:block}.author h2,.author p,.author strong{color:#fff}.author .eyebrow{color:#d7eaff}.author p:last-child{margin-bottom:0}.author h2{font-size:clamp(1.5rem,2.2vw,2rem);line-height:1.25}
.prose{max-width:790px;line-height:1.82}.prose>p{margin-bottom:1.4em}.prose h3{line-height:1.3;border-top:2px solid #d9e7f7;padding-top:23px}.prose .scene{margin:34px 0 44px}.scene figcaption{border-top:4px solid var(--blue);padding:23px 25px}.scene .observe{padding:12px 15px;border-left:3px solid var(--blue);background:var(--pale);color:var(--navy)}
.book-card{box-shadow:0 10px 28px #073d7808;border-radius:14px}.official{border-left:5px solid var(--blue);border-radius:0 12px 12px 0;padding:23px 25px}.lesson-head .eyebrow{font-size:.875rem}.sidebar nav a{font-size:.9rem}.sidebar nav a:hover{background:#e3effd}.sidebar nav a[aria-current=page]:hover{background:var(--navy)}
@media(max-width:1150px){.hero{display:flex;flex-direction:column;min-height:0}.hero>img{position:relative;inset:auto;order:0;width:100%;height:280px;min-height:0;max-height:none;object-position:center 45%;mask-image:linear-gradient(to bottom,#000 65%,transparent 100%);-webkit-mask-image:linear-gradient(to bottom,#000 65%,transparent 100%)}.hero-copy{order:1;width:100%;padding:15px 32px 32px;margin-top:-25px}.hero h1{font-size:2.6rem}.hero-copy p{max-width:45ch}.author{grid-template-columns:180px minmax(0,1fr);gap:25px}.author img{width:180px}}
@media(max-width:760px){.hero>img{height:215px}.hero-copy{padding:12px 24px 28px}.hero h1{font-size:2.2rem}.hero-facts{gap:7px}.hero-facts span{font-size:.8rem}.author{grid-template-columns:1fr;padding:24px;gap:25px}.author img{width:200px;margin:auto}.author h2{font-size:1.7rem}.scene figcaption{padding:18px}.official{padding:18px}.prose{line-height:1.8}}
@media print{.hero-copy{width:100%}.hero>img{display:none}.author{background:#fff;border:1px solid var(--line)}.author h2,.author p,.author strong,.author .eyebrow{color:var(--ink)}}

/* Purpose-first orientation, added without changing existing learning controls. */
.unit-purpose{margin:40px 0 52px;padding:30px clamp(22px,3vw,40px);background:#fff;border:1px solid var(--line);border-top:5px solid var(--blue);border-radius:16px}.unit-purpose h2{margin-top:0}.unit-purpose>p,.unit-purpose>h3{max-width:850px}.unit-purpose h3{margin-top:30px;line-height:1.35}.unit-purpose table{min-width:640px}
.section-purpose{margin:36px 0 24px;padding:28px;background:var(--pale);border-left:5px solid var(--blue);border-radius:0 14px 14px 0}.section-purpose h2{margin-top:0}.section-purpose>p{max-width:860px}.section-purpose-summary{font-size:.93rem;line-height:1.7}.section-purpose-detail summary{font-weight:700;cursor:pointer;color:var(--navy);line-height:1.5}.section-purpose-detail p{margin-top:15px}
.lesson-purpose{border:1px solid var(--line);border-left:5px solid var(--blue);border-radius:0 14px 14px 0;background:#f1f7ff;padding:27px 30px;margin-bottom:26px}.lesson-purpose h2{font-size:1.65rem;margin:0 0 18px}.lesson-purpose h3{font-size:1.08rem;margin:20px 0 12px}.lesson-purpose p:last-child{margin-bottom:0}.section-entry{padding:23px 27px;border:1px solid var(--line);background:white;border-radius:12px;margin:0 0 25px}.section-entry>strong{color:var(--navy);display:block;margin-bottom:10px}.section-entry p:last-child{margin-bottom:0}
.prose .topic-purpose{font-size:1rem;color:var(--navy);border-left:3px solid #6ca0d8;background:#edf5ff;padding:15px 18px;line-height:1.7;margin:0 0 25px}.topic-purpose strong{display:block;margin-bottom:5px}.section-card:first-child .section-purpose-summary{color:#fff}
@media(max-width:760px){.unit-purpose{padding:24px 19px}.section-purpose,.lesson-purpose,.section-entry{padding:22px 18px}.unit-purpose table{font-size:.875rem}.prose .topic-purpose{font-size:1rem;padding:15px}}

/* AC 1.4–1.6: full-scene images with compact purpose and discussion boxes. */
.prose .hazard-figure{margin:30px 0 40px;background:#fff;border:1px solid var(--line);border-radius:16px;overflow:hidden;box-shadow:0 8px 24px #073d7808;scroll-margin-top:110px}
.hazard-figure>img{display:block;width:100%;height:auto;max-height:none;object-fit:contain}
.hazard-figure figcaption{padding:22px 24px;border-top:4px solid var(--blue)}
.hazard-figure h4{font-size:1.2rem;line-height:1.4;color:var(--navy);margin:0 0 16px;padding:0}
.hazard-purpose{background:var(--pale);border-left:4px solid var(--blue);border-radius:0 9px 9px 0;padding:14px 17px;color:var(--navy);font-size:1rem;line-height:1.65}
.hazard-purpose>strong{display:block;margin-bottom:5px}
.hazard-purpose p{margin:0}
.hazard-question{font-size:1rem;line-height:1.65;margin:16px 0 0}
.hazard-figure figcaption .hazard-question>strong{display:inline}
.hazard-note{font-size:.9rem;line-height:1.6;color:var(--muted);margin:16px 0 0}
.hazard-note a{text-decoration:underline;text-underline-offset:3px}
@media(max-width:760px){.hazard-figure figcaption{padding:18px}.hazard-purpose{padding:13px 15px}.prose .hazard-figure{scroll-margin-top:86px}}
@media print{.hazard-figure{break-inside:avoid;box-shadow:none}}