@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans+Thai:wght@300;400;500;600;700&family=Space+Grotesk:wght@400;500;600;700&display=swap');
:root{--bg:#07111f;--panel:#101e31;--panel2:#172941;--line:#29435d;--ink:#edf5ff;--muted:#a6b9cf;--mint:#6ef0cf;--cyan:#7dd3fc;--gold:#ffd27d;--pink:#ff8da1;--green:#86f7b5;--shadow:0 18px 50px #0003}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:radial-gradient(ellipse at 5% 0%,#143a4b 0,transparent 35%),radial-gradient(ellipse at 90% 5%,#202b4d 0,transparent 30%),var(--bg);color:var(--ink);font-family:'IBM Plex Sans Thai',system-ui,sans-serif;line-height:1.6}button,input,select{font:inherit}button{cursor:pointer}.shell{width:min(1200px,92%);margin:auto}.top{position:sticky;top:0;z-index:30;background:#07111fe8;backdrop-filter:blur(18px);border-bottom:1px solid #29435d99}.nav{min-height:76px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--ink);font:700 1.05rem 'Space Grotesk',sans-serif;letter-spacing:.7px}.brand small{display:block;font:500 .65rem 'IBM Plex Sans Thai';color:var(--muted);letter-spacing:2px}.mark{width:45px;height:45px;display:grid;place-items:center;border-radius:15px;color:#041a26;font-size:24px;background:linear-gradient(135deg,var(--mint),var(--cyan));box-shadow:0 0 30px #6ef0cf2a}.links{display:flex;gap:5px;flex-wrap:wrap}.links a{color:var(--muted);text-decoration:none;padding:9px 12px;border-radius:11px;font-size:.92rem;transition:.2s}.links a:hover,.links a.active{background:#17374a;color:var(--mint)}.hero{padding:64px 0 36px;display:grid;grid-template-columns:1.15fr .85fr;gap:32px;align-items:center}.eyebrow{color:var(--mint);font-size:.78rem;letter-spacing:2.5px;text-transform:uppercase;font-weight:700}.hero h1{font-size:clamp(2.6rem,6vw,5.4rem);line-height:1.04;letter-spacing:-2px;margin:14px 0 20px;font-weight:700}.hero h1 em{font-style:normal;color:var(--mint)}.lead{font-size:1.1rem;color:var(--muted);max-width:630px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid transparent;border-radius:13px;padding:12px 18px;font-weight:700;text-decoration:none;transition:transform .2s,filter .2s}.btn:hover{transform:translateY(-2px);filter:brightness(1.08)}.primary{background:linear-gradient(120deg,var(--mint),var(--cyan));color:#061a26}.secondary{background:#15273c;color:var(--ink);border-color:var(--line)}.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:24px}.art{min-height:300px;display:grid;place-items:center;position:relative;overflow:hidden;border:1px solid #34536a;border-radius:30px;background:linear-gradient(145deg,#152d41bb,#0b1b2bcc);box-shadow:var(--shadow)}.art:before,.art:after{content:'';position:absolute;border:1px solid #6ef0cf55;border-radius:50%;width:230px;height:100px;transform:rotate(-35deg)}.art:after{transform:rotate(35deg);border-color:#7dd3fc88}.orb{width:128px;height:128px;border-radius:50%;display:grid;place-items:center;font-size:60px;z-index:1;background:radial-gradient(circle at 35% 30%,#8ffff0,#1e9a9e 42%,#102a4b 74%);box-shadow:0 0 70px #6ef0cf45}.bubble{position:absolute;border-radius:50%;background:var(--gold);box-shadow:0 0 20px #ffd27d77}.b1{width:12px;height:12px;top:22%;left:22%}.b2{width:8px;height:8px;right:20%;top:30%;background:var(--pink)}.b3{width:10px;height:10px;bottom:22%;left:28%;background:var(--cyan)}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:13px;margin:10px auto 42px}.stat,.card{background:linear-gradient(145deg,#12243aee,#0c1b2eee);border:1px solid #29435d;border-radius:20px;box-shadow:var(--shadow)}.stat{padding:18px 20px}.stat strong{display:block;font:700 1.8rem 'Space Grotesk';color:var(--mint)}.stat span{color:var(--muted);font-size:.9rem}.section{padding:32px 0 48px;scroll-margin-top:90px}.head{display:flex;align-items:end;justify-content:space-between;gap:18px;margin-bottom:22px}.head h2{font-size:clamp(1.8rem,3.5vw,2.7rem);margin:5px 0}.head p{margin:0;color:var(--muted)}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.category{padding:23px;text-align:left;min-height:170px;color:var(--ink);transition:.22s;position:relative;overflow:hidden}.category:hover{transform:translateY(-4px);border-color:var(--mint)}.category .emoji{font-size:30px}.category h3{margin:10px 0 4px}.category p{margin:0;color:var(--muted);font-size:.92rem}.category:after{content:'↗';position:absolute;right:18px;top:16px;color:var(--mint);opacity:.8}.pageintro{padding:44px 0 18px}.pageintro h1{font-size:clamp(2.1rem,5vw,3.8rem);line-height:1.1;margin:8px 0}.pageintro p{color:var(--muted);max-width:800px}.layout{display:grid;grid-template-columns:245px 1fr;gap:18px}.side{padding:16px;height:max-content;position:sticky;top:95px}.side h3{margin:0 0 12px}.side button{display:block;width:100%;text-align:left;background:transparent;color:var(--muted);padding:10px 12px;border-radius:11px;margin:3px 0;border:0}.side button:hover,.side button.selected{background:#193b50;color:var(--mint)}.practice{padding:clamp(17px,3vw,30px)}.row{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}.pill{display:inline-flex;align-items:center;background:#17394b;color:var(--mint);border:1px solid #2a5867;border-radius:99px;padding:5px 11px;font-size:.82rem;font-weight:700}.equation{display:flex;align-items:center;justify-content:center;gap:10px;flex-wrap:wrap;padding:26px 8px;margin:14px 0;background:#071523;border:1px solid var(--line);border-radius:17px}.species{display:flex;align-items:center;gap:6px;white-space:nowrap}.formula{font-size:clamp(1rem,2.3vw,1.4rem);font-weight:700}.formula sub{font-size:.7em}.operator{font-size:1.5rem;color:var(--cyan);font-weight:800}.coef{display:flex;align-items:center;gap:4px;background:#173149;border:1px solid #34536a;border-radius:11px;padding:4px}.coef button{width:28px;height:30px;border-radius:8px;background:#2b4a63;color:#fff;font-weight:900;font-size:1.1rem}.coef input{width:30px;text-align:center;background:transparent;color:var(--mint);border:0;font-weight:800;outline:none}.answer-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:16px}.feedback{padding:14px 16px;border-radius:13px;margin-top:15px;display:none}.feedback.good{display:block;background:#123c35;border:1px solid #287c62;color:#c0ffe5}.feedback.bad{display:block;background:#452532;border:1px solid #8d465b;color:#ffd9df}.hint,.muted{color:var(--muted);font-size:.92rem}.progressbar{height:8px;background:#1b344a;border-radius:9px;overflow:hidden;margin:13px 0}.progressbar div{height:100%;background:linear-gradient(90deg,var(--mint),var(--cyan));width:0%;transition:width .3s}.lesson-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:15px}.lesson{padding:23px}.lesson h3{color:var(--mint);margin-top:0}.lesson p,.lesson li{color:var(--muted)}.example{padding:12px 14px;border-radius:11px;background:#071523;border:1px solid var(--line);margin:10px 0}.field{display:block;width:100%;padding:12px 14px;border-radius:12px;background:#071523;border:1px solid var(--line);color:var(--ink)}label{display:block;margin:12px 0 6px;color:var(--muted)}.quiz{padding:23px}.tablewrap{overflow-x:auto;padding:16px}.ptable{display:grid;grid-template-columns:repeat(18,minmax(43px,1fr));gap:5px;min-width:900px}.element{position:relative;min-height:68px;border:1px solid #34536a;border-radius:9px;background:#142a40;color:var(--ink);padding:5px 3px;text-align:center;transition:.16s}.element:hover{transform:scale(1.07);z-index:2;border-color:white}.element .num{display:block;text-align:left;font-size:.62rem;color:#b3c7d8;padding-left:3px}.element b{display:block;font:700 1.15rem 'Space Grotesk'}.element small{display:block;font-size:.57rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.alkali{background:#493047;border-color:#98577b}.alkaline{background:#5a3d31;border-color:#bb805b}.transition{background:#253e66;border-color:#4e7ec0}.post{background:#214c52;border-color:#4a9d9c}.metalloid{background:#46502d;border-color:#91a65c}.nonmetal{background:#164f45;border-color:#47a990}.halogen{background:#4c3f72;border-color:#9a85d4}.noble{background:#5a3e67;border-color:#b88bd0}.lanth{background:#514326;border-color:#bba253}.act{background:#5a343a;border-color:#bd6c7a}.empty{visibility:hidden}.legend{display:flex;flex-wrap:wrap;gap:8px;margin:14px 0}.legend span{font-size:.82rem;color:var(--muted);display:flex;align-items:center;gap:6px}.dot{width:10px;height:10px;border-radius:3px;display:inline-block}.element-detail{display:grid;grid-template-columns:110px 1fr;gap:18px;padding:22px;margin-top:16px}.detail-symbol{display:grid;place-items:center;align-content:center;background:#17394b;border:1px solid #3b6577;border-radius:17px;min-height:120px}.detail-symbol b{font:700 3rem 'Space Grotesk';color:var(--mint)}.detail-symbol span{color:var(--muted)}.detail-content h3{margin:0 0 5px}.detail-content p{color:var(--muted);margin:5px 0}.prefixgrid{display:grid;grid-template-columns:repeat(2,1fr);gap:9px}.prefix{padding:12px;border:1px solid var(--line);border-radius:12px;background:#0b1b2b}.prefix b{color:var(--mint)}.footer{margin-top:30px;border-top:1px solid var(--line);padding:28px 0;color:var(--muted);font-size:.9rem}.footer p{margin:6px 0}.notice{font-size:.82rem;color:var(--muted);margin-top:12px}
@media(max-width:900px){.hero{grid-template-columns:1fr}.art{min-height:230px}.grid{grid-template-columns:repeat(2,1fr)}.layout{grid-template-columns:1fr}.side{position:static;display:flex;overflow:auto;gap:5px;white-space:nowrap}.side h3{display:none}.side button{width:auto;flex:0 0 auto}.ptable{min-width:850px}}
@media(max-width:600px){.nav{align-items:flex-start;padding:12px 0}.links{max-width:210px;justify-content:flex-end}.links a{padding:7px 8px;font-size:.8rem}.brand{font-size:.9rem}.mark{width:39px;height:39px}.hero{padding-top:35px}.stats{gap:7px}.stat{padding:12px}.stat strong{font-size:1.35rem}.grid,.lesson-grid,.prefixgrid{grid-template-columns:1fr}.head{align-items:flex-start;flex-direction:column}.equation{gap:7px;padding:15px 5px}.formula{font-size:.98rem}.coef button{width:24px;height:27px}.coef input{width:23px}.element-detail{grid-template-columns:1fr}.detail-symbol{min-height:100px}.pageintro{padding-top:30px}}

/* Added family markers for the f-block series */
.dot.lanthanide{background:#d7a7ff}.dot.actinide{background:#f3a76b}