:root{--blue:#0647b8;--blue2:#0b63e5;--ink:#11213b;--muted:#617087;--line:#d9e3ef;--soft:#f4f8ff;--shadow:0 18px 50px rgba(20,46,88,.11)}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font:16px/1.58 Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif;color:var(--ink);background:#fff}
button,input,select{font:inherit}
.site-header{height:76px;max-width:1160px;margin:auto;padding:0 22px;display:flex;align-items:center;justify-content:space-between}
.brand img{display:block;width:230px;height:auto}
.site-header nav{display:flex;gap:25px}
.site-header nav a,footer a{font-size:14px;font-weight:750;color:#48566a;text-decoration:none}
.site-header nav a:hover,footer a:hover{color:var(--blue)}
.home-hero{max-width:1160px;margin:auto;padding:68px 22px 62px;display:grid;grid-template-columns:1.05fr .95fr;gap:70px;align-items:center}
.eyebrow{display:block;color:var(--blue);font-size:12px;font-weight:900;letter-spacing:.14em;margin-bottom:13px}
.home-hero h1,.page-intro h1{font-size:clamp(44px,6vw,70px);line-height:1.02;letter-spacing:-.055em;margin:0 0 20px}
.home-hero h1 span{color:var(--blue)}
.home-hero p,.page-intro p{font-size:19px;color:var(--muted);margin:0;max-width:660px}
.example-board{background:#10233f;color:#fff;border-radius:24px;padding:30px;box-shadow:var(--shadow);transform:rotate(1deg)}
.example-board .problem{font-family:Georgia,serif;font-size:35px;border-bottom:1px solid #415472;padding-bottom:17px;margin-bottom:17px}
.example-board ol{margin:0;padding-left:25px;color:#d8e6f7}
.example-board li{padding:6px}
.example-board b{color:#78b2ff}
.tools{background:var(--soft);padding:70px max(22px,calc((100% - 1116px)/2))}
.section-heading{display:flex;justify-content:space-between;align-items:end;margin-bottom:24px}
.section-heading h2{font-size:36px;letter-spacing:-.04em;margin:0}
.section-heading p{color:var(--muted);max-width:520px;margin:0}
.tool-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}
.tool-card{display:grid;grid-template-columns:60px 1fr;gap:17px;border:1px solid var(--line);border-radius:18px;background:#fff;padding:24px;text-decoration:none;color:var(--ink);transition:.2s}
.tool-card:hover{transform:translateY(-3px);border-color:#9fc5fc;box-shadow:0 12px 30px rgba(20,58,110,.1)}
.tool-icon{width:58px;height:58px;border-radius:15px;background:#e7f0ff;color:var(--blue);display:grid;place-items:center;font:900 25px Georgia,serif}
.tool-card h3{font-size:21px;margin:1px 0 6px}
.tool-card p{margin:0;color:var(--muted);font-size:14px}
.tool-card small{display:block;color:var(--blue);font-weight:850;margin-top:11px}
.learning{max-width:1160px;margin:auto;padding:72px 22px}
.learning h2{font-size:35px;letter-spacing:-.035em}
.learning-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.learning article{border-top:4px solid var(--blue);padding-top:18px}
.learning h3{margin:0 0 7px}
.learning p{color:var(--muted);margin:0}
.solver-page{max-width:1080px;margin:auto;padding:30px 22px 78px}
.breadcrumbs{display:flex;gap:9px;font-size:13px;color:#7a8799;margin-bottom:32px}
.breadcrumbs a{color:var(--blue);text-decoration:none}
.page-intro{max-width:760px;margin-bottom:30px}
.page-intro h1{font-size:clamp(40px,5vw,60px)}
.workspace{display:grid;grid-template-columns:.9fr 1.1fr;gap:22px;align-items:start}
.input-card,.steps-card{border:1px solid var(--line);border-radius:20px;background:#fff;padding:28px;box-shadow:var(--shadow)}
.input-card h2,.steps-card h2{font-size:24px;margin:0 0 20px}
.math-form{display:grid;gap:15px}
.math-form label{font-size:14px;font-weight:800;color:#46556b}
.math-form input,.math-form select{display:block;width:100%;margin-top:6px;border:1px solid #c5d2e2;border-radius:10px;padding:12px;outline:none;background:#fff}
.math-form input:focus,.math-form select:focus{border-color:var(--blue2);box-shadow:0 0 0 3px rgba(11,99,229,.13)}
.fraction-entry{display:grid;grid-template-columns:1fr 72px 1fr;gap:13px;align-items:end}
.fraction-pair{display:grid;grid-template-rows:1fr 1fr;gap:5px}
.fraction-pair input:first-child{border-bottom:2px solid var(--ink)}
.solve-button{border:0;border-radius:11px;background:var(--blue);color:#fff;font-weight:850;padding:13px 18px;margin-top:4px}
.solve-button:hover{background:#04398f}
.answer-box{background:linear-gradient(135deg,#0647b8,#0b63e5);color:#fff;border-radius:15px;padding:20px;margin-bottom:20px}
.answer-box span{display:block;font-size:11px;letter-spacing:.14em;font-weight:900;color:#cfe0ff}
.answer-box strong{display:block;font:700 36px/1.25 Georgia,serif;margin-top:4px}
.steps-list{list-style:none;margin:0;padding:0;counter-reset:steps}
.steps-list li{counter-increment:steps;display:grid;grid-template-columns:34px 1fr;gap:12px;padding:13px 0;border-top:1px solid var(--line)}
.steps-list li:before{content:counter(steps);width:28px;height:28px;border-radius:50%;background:#e8f1ff;color:var(--blue);display:grid;place-items:center;font-weight:900}
.steps-list b{display:block}
.steps-list code{font:700 18px/1.5 Georgia,serif;color:#203e67}
.error{background:#fff1f1;color:#a12626;border:1px solid #f2c5c5;border-radius:10px;padding:12px}
.lesson{margin-top:48px;display:grid;grid-template-columns:1fr 1fr;gap:22px}
.lesson article{border:1px solid var(--line);border-radius:17px;padding:25px}
.lesson h2{font-size:24px;margin-top:0}
.lesson p,.lesson li{color:var(--muted)}
.worked-example{background:var(--soft)}
.related{margin-top:48px}
.related h2{font-size:29px}
.related-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}
.related-grid a{border:1px solid var(--line);border-radius:14px;padding:18px;text-decoration:none;color:var(--ink);font-weight:850}
.related-grid a:hover{border-color:#9fc5fc}
.related-grid small{display:block;color:var(--muted);font-weight:500;margin-top:5px}
footer{background:#0c1b31;color:#d7e2f0;padding:55px max(22px,calc((100% - 1116px)/2)) 26px;display:grid;grid-template-columns:2fr 1fr 1fr;gap:38px}
.footer-brand img{display:block;width:250px;max-width:100%;height:auto}
footer p{color:#9db0c8;max-width:460px;font-size:14px}
footer h3{font-size:14px;color:#fff;margin:0 0 12px}
footer a{display:block;color:#b8c8da;margin:7px 0}
.copyright{grid-column:1/-1;border-top:1px solid #263951;padding-top:23px;color:#8397ae;font-size:13px}
@media(max-width:820px){.home-hero,.workspace{grid-template-columns:1fr}
.example-board{transform:none}
.tool-grid,.lesson,.learning-grid{grid-template-columns:1fr}
.section-heading{display:block}
.section-heading p{margin-top:8px}
.related-grid{grid-template-columns:1fr}
.site-header nav a:not(:last-child){display:none}
}
@media(max-width:580px){.site-header{height:68px;padding:0 17px}
.brand img{width:185px}
.site-header nav a:last-child{font-size:12px}
.home-hero,.solver-page{padding-left:17px;padding-right:17px}
.home-hero h1{font-size:44px}
.tools{padding-left:17px;padding-right:17px}
.tool-grid{grid-template-columns:1fr}
.fraction-entry{grid-template-columns:1fr}
.fraction-pair{grid-template-columns:1fr 1fr;grid-template-rows:1fr}
.fraction-pair input:first-child{border-bottom:1px solid #c5d2e2}
.input-card,.steps-card{padding:21px}
footer{grid-template-columns:1fr}
.copyright{grid-column:1}
}

.resources{background:#f5f8ff;padding:70px max(22px,calc((100% - 1116px)/2))}
.resource-grid{display:grid;grid-template-columns:1fr 1fr;gap:45px}
.resources h2{font-size:30px;letter-spacing:-.03em;margin-top:0}
.resources dl{display:grid;grid-template-columns:130px 1fr;margin:0}
.resources dt,.resources dd{padding:10px 0;border-top:1px solid var(--line)}
.resources dt{font-weight:850}
.resources dd{margin:0;color:var(--muted)}
.faq details{border-top:1px solid var(--line);padding:14px 0}
.faq details:last-child{border-bottom:1px solid var(--line)}
.faq summary{font-weight:850;cursor:pointer}
.faq p{color:var(--muted);margin:8px 0 0}
@media(max-width:760px){.resource-grid{grid-template-columns:1fr}.resources dl{grid-template-columns:1fr}.resources dd{padding-top:0}}
.site-header nav{gap:20px}
.site-header nav a[aria-current=page]{color:var(--blue)}
@media(max-width:1279px) and (min-width:821px){.site-header{height:auto;flex-wrap:wrap;gap:10px 24px;padding-top:14px;padding-bottom:14px}.site-header nav{flex-wrap:wrap;gap:6px 20px}}
.form-buttons{display:flex;flex-wrap:wrap;gap:10px}
.reset-button{border:1px solid #c5d2e2;border-radius:11px;background:#fff;color:#46556b;font-weight:850;padding:13px 18px;margin-top:4px;cursor:pointer}
.reset-button:hover{border-color:var(--blue2);color:var(--blue)}
.result-actions{display:flex;align-items:center;flex-wrap:wrap;gap:10px;margin:-6px 0 18px}
.copy-button{border:1px solid #9fc5fc;border-radius:999px;background:#e8f1ff;color:var(--blue);font-size:14px;font-weight:850;padding:9px 16px;cursor:pointer}
.copy-button:hover:not(:disabled){background:var(--blue);color:#fff}
.copy-button:disabled{opacity:.5;cursor:not-allowed}
.copy-status{font-size:13px;font-weight:750;color:var(--muted)}
.steps-list li.error{display:block;counter-increment:none;padding:12px;border:1px solid #f2c5c5}
.steps-list li.error:before{content:none}