@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans+Thai:wght@400;500;600;700&display=swap');
:root{--navy:#111e35;--orange:#ed632f;--ink:#1c2b40;--muted:#718093;--line:#e3e8ee}*{box-sizing:border-box}body{margin:0;background:#f5f7fa;color:var(--ink);font-family:'IBM Plex Sans Thai',system-ui,sans-serif;font-size:16px}button,a,input{font:inherit}a{color:inherit;text-decoration:none}button{cursor:pointer}button:focus-visible,a:focus-visible{outline:3px solid #ec8a42;outline-offset:4px}aside{position:fixed;inset:0 auto 0 0;width:240px;background:var(--navy);color:#fff;padding:32px 22px;display:flex;flex-direction:column}.brand{font-size:24px;font-weight:700;letter-spacing:-.8px}.logo{display:inline-flex;font-size:26px;border:1px solid #546073;border-radius:10px;width:42px;height:42px;align-items:center;justify-content:center;margin-right:8px}.logo span{color:var(--orange);font-size:12px}.brand-sub{display:block;font-size:14px;font-weight:400;letter-spacing:0;color:#adb7c7;margin:10px 0 0 53px}.nav-label{font-size:12px;color:#8593a9;margin:58px 14px 16px}nav a{display:flex;gap:13px;padding:14px;border-radius:8px;margin-bottom:8px;font-size:15px;color:#b4bfd1}nav a.active{background:#2a3447;color:white;border-left:3px solid var(--orange)}.aside-bottom{margin-top:auto;border-top:1px solid #344057;padding-top:24px;display:flex;gap:12px;font-size:14px}.aside-bottom small{font-size:12px;color:#9eabbe}.mini-logo{background:#e56735;padding:8px 14px;border-radius:9px;height:40px;font-weight:bold}.shell{margin-left:240px}header{height:82px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 44px;font-size:13px;color:#69778a}header b{margin:0 14px;color:#b3bfce;font-weight:400}.profile{display:flex;align-items:center;gap:14px}.profile i{background:#edf0f6;color:#384860;font-size:13px;font-style:normal;border-radius:50%;padding:11px}main{max-width:1300px;padding:38px 44px 30px;margin:auto}h1{font-size:30px;margin:0 0 6px;letter-spacing:-.5px}h2{font-size:21px;margin:0}p{line-height:1.8}.sub{color:var(--muted);margin:0}.eyebrow{font-size:12px;font-weight:600;letter-spacing:2px;color:var(--orange);margin-bottom:10px}.topline{display:flex;align-items:center;justify-content:space-between;margin-bottom:27px;gap:18px}.pill{border:1px solid #dde3ea;background:#fff;border-radius:30px;padding:7px 14px;color:#677487;font-size:13px}.continue{background:var(--navy);border-radius:16px;color:white;display:grid;grid-template-columns:1.5fr 1fr;overflow:hidden;margin:28px 0}.continue-copy{padding:32px}.continue .eyebrow{color:#ffab80}.continue h2{font-size:28px}.continue p{color:#bec8d6;margin:8px 0 23px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:20px;background:var(--orange);color:white;border:0;border-radius:7px;padding:11px 21px;font-weight:500}.btn:hover{background:#d85120}.btn.secondary{background:white;color:var(--ink);border:1px solid var(--line)}.formula{display:flex;flex-direction:column;align-items:center;justify-content:center;background:#1d2c44;border-left:1px solid #344259;position:relative;padding:30px}.formula strong{font-family:Georgia,serif;font-style:italic;font-size:65px;color:#f2f5fa;font-weight:400}.formula small{color:#91a1b9;letter-spacing:3px;margin-top:18px;font-size:12px}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-bottom:34px}.stat{background:white;border:1px solid var(--line);border-radius:10px;padding:19px 22px;display:flex;align-items:center;gap:18px}.stat .symbol{background:#f2f5fa;border-radius:10px;padding:9px 14px;font-size:23px;color:#62768c}.stat strong{font-size:25px}.stat small{font-size:14px;color:var(--muted);display:block}.section-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:18px}.text-link{font-size:14px;color:var(--orange)}.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}.card{background:#fff;border:1px solid var(--line);border-radius:12px;overflow:hidden}.cover{height:155px;padding:22px 24px;background:#dce6f1;position:relative;display:flex;flex-direction:column;justify-content:space-between;overflow:hidden}.cover.c1{background:#dfe9ef;color:#283f56}.cover.c2{background:#f7e2d7;color:#713a27}.cover.c3{background:#e4e3f1;color:#443f67}.cover small{font-size:12px;letter-spacing:1.4px;font-weight:600}.cover strong{font-size:27px;z-index:1;line-height:1.2}.cover em{position:absolute;right:13px;top:40px;font:italic 40px Georgia;opacity:.2;transform:rotate(-12deg)}.cover span{font-size:12px}.card-body{padding:21px}.card h3{font-size:17px;margin:0 0 9px}.meta{color:var(--muted);font-size:13px}.progress-label{display:flex;justify-content:space-between;font-size:12px;color:var(--muted);margin-top:21px}progress{width:100%;height:6px;display:block;border:0;border-radius:4px;margin:8px 0 19px;appearance:none;background:#e9edf2}progress::-webkit-progress-bar{background:#e9edf2;border-radius:4px}progress::-webkit-progress-value{background:var(--orange);border-radius:4px}progress::-moz-progress-bar{background:var(--orange)}.card .btn{width:100%;font-size:14px;padding:9px}.note{font-size:13px;color:var(--muted);margin-top:20px}footer{margin:20px 44px 0;padding:23px 0;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:12px;color:#8490a0;font-size:12px}.back{display:inline-block;color:#768395;font-size:14px;margin-bottom:22px}.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:24px;margin-top:25px}.reading{background:#fff;border:1px solid var(--line);border-radius:12px;overflow:hidden}.lesson-banner{background:var(--navy);color:#fff;padding:32px}.lesson-banner .equation{font:italic 42px Georgia;margin:24px 0 10px}.lesson-body{padding:30px}.lesson-body h3{margin:0 0 12px}.lesson-body p{color:#57657a}.callout{border-left:3px solid var(--orange);background:#fff5ee;padding:15px 20px;line-height:1.9;margin:24px 0}.lesson-list{background:white;border:1px solid var(--line);border-radius:12px;padding:22px;height:fit-content}.lesson-list h3{margin-top:0;font-size:17px}.lesson-item{width:100%;border:0;border-bottom:1px solid var(--line);background:white;padding:17px 10px;text-align:left;display:flex;gap:12px;font-size:14px;line-height:1.65}.lesson-item.selected{background:#fff1e8;color:#be4b20;border-radius:6px}.lesson-item small{color:var(--muted);display:block}.quiz{border-top:1px solid var(--line);padding-top:24px;margin-top:28px}.choices{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:18px 0}.choice{padding:12px;border:1px solid var(--line);border-radius:7px;background:white;text-align:left}.choice.chosen{border-color:var(--orange);background:#fff1e8}.feedback{padding:14px;border-radius:6px;line-height:1.8;background:#edf4fa;margin-bottom:18px}.lesson-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:25px}@media(min-width:1500px){main{padding-top:48px}.cover{height:190px}}@media(max-width:1100px){aside{width:200px;padding:28px 16px}.brand{font-size:20px}.shell{margin-left:200px}main{padding:28px}.cards{gap:12px}.card-body{padding:16px}.lesson-layout{grid-template-columns:1fr}.lesson-list{order:-1}.lesson-item{padding:10px}.cover strong{font-size:23px}header{padding:0 28px}.formula strong{font-size:50px}}@media(max-width:760px){aside{position:static;width:auto;padding:17px 20px;display:block}.brand-sub,.nav-label,.aside-bottom{display:none}.brand{display:block;font-size:22px}.logo{height:34px;width:34px;font-size:22px}nav{display:flex;margin-top:16px;gap:7px}nav a{padding:9px 12px;margin:0;font-size:14px}.shell{margin-left:0}header{height:60px;padding:0 20px}header>span:first-child{font-size:11px}.profile{font-size:12px;gap:8px}main{padding:25px 20px}h1{font-size:25px}.topline .pill{display:none}.continue{grid-template-columns:1fr}.continue-copy{padding:25px}.continue h2{font-size:24px}.formula{display:none}.stats{gap:8px}.stat{padding:14px 10px;display:block}.stat .symbol{display:none}.stat strong{font-size:23px}.stat small{font-size:12px}.cards{grid-template-columns:1fr}.cover{height:145px}.card-body{padding:20px}.section-head h2{font-size:19px}footer{margin:10px 20px;flex-direction:column}.lesson-body,.lesson-banner{padding:23px}.choices{grid-template-columns:1fr}}

/* Keep navigation reachable on short screens and when text is enlarged. */
aside{overflow-y:auto;overflow-x:hidden;-webkit-overflow-scrolling:touch;scrollbar-width:thin;scrollbar-color:#718093 #111e35}
aside>*{flex-shrink:0}
@media(max-width:760px){aside{overflow:visible}nav{overflow-x:auto;max-width:100%;padding-bottom:5px;-webkit-overflow-scrolling:touch}nav a{flex-shrink:0;white-space:nowrap}}

.video-block{padding:24px 24px 0}.video-block iframe{width:100%;aspect-ratio:16/9;border:0;background:#111e35;border-radius:8px}.video-block a{display:block;font-size:13px;color:#718093;margin-top:10px}.lesson-body p,.callout{white-space:pre-line}
.member-lock{padding:36px 22px;background:#f1f4f9;border:1px solid #e1e7ef;border-radius:10px;text-align:center}.member-lock h3{font-size:22px;margin:12px 0}.member-lock p{color:#718093;margin:10px 0 20px}.lock-icon{font-size:34px;color:#ed632f}.profile a{font-size:14px}.profile .signout{font-size:12px;color:#8490a0}@media(max-width:760px){header{height:auto;min-height:66px;gap:12px;flex-wrap:wrap;padding-top:12px;padding-bottom:12px}.profile{flex-wrap:wrap}.member-lock{padding:24px 15px}.member-lock h3{font-size:20px}}