:root{--ink:#17212d;--muted:#556270;--blue:#1e73be;--blue2:#eaf4ff;--yellow:#fff7d6;--line:#dbe4ec;--bg:#f5f7fa;--card:#fff;--code:#101827}
*{box-sizing:border-box}html,body{margin:0;max-width:100%;overflow-x:clip}html{scroll-behavior:smooth}body{font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--bg);line-height:1.68}
img,svg,video,canvas{max-width:100%;height:auto}pre,code{max-width:100%}a{color:#145f9d;text-decoration:none}a:hover{text-decoration:underline}
.skip{position:absolute;left:-9999px;top:0}.skip:focus{left:8px;top:8px;z-index:100;background:white;padding:8px;border-radius:6px}
.topbar{position:sticky;top:0;z-index:40;background:linear-gradient(135deg,#14213d 0%,#1f5f99 52%,#2d7fb8 100%);box-shadow:0 2px 12px #0002}.topbar-in{max-width:1240px;margin:auto;padding:8px 16px;display:flex;align-items:center;gap:16px}.brand{display:flex;align-items:center}.brand img{width:230px;display:block}.site-nav{margin-left:auto}.site-nav ul{display:flex;align-items:center;gap:8px;list-style:none;padding:0;margin:0}.site-nav a{display:block;color:#fff;padding:9px 10px;border-radius:8px}.site-nav a:hover{background:#ffffff18;text-decoration:none}.site-toggle{display:none;margin-left:auto;border:1px solid #ffffff44;background:#ffffff12;color:#fff;border-radius:8px;padding:9px 12px}
.translator-wrap{background:#eef4f8;border-bottom:1px solid var(--line)}.translator-in{max-width:1240px;margin:auto;padding:6px 16px;display:flex;align-items:center;gap:10px;min-height:42px}.translator-label{font-weight:700;font-size:.92rem}.translator-slot{min-height:28px;max-width:100%}
.hero{background:linear-gradient(135deg,var(--blue2),#fff,var(--yellow));border-bottom:1px solid var(--line)}.hero-in{max-width:1240px;margin:auto;padding:25px 16px}.crumbs{font-size:.9rem;color:var(--muted);margin-bottom:6px}.hero h1{font-size:clamp(1.75rem,4vw,3rem);line-height:1.16;margin:0 0 10px}.hero p{max-width:920px;margin:0;color:#344452}
.controls{max-width:1240px;margin:10px auto 12px;padding:0 16px;display:flex;flex-wrap:wrap;gap:8px}.controls button,.chapter-open{border:1px solid #cbd6df;background:#fff;color:var(--ink);border-radius:9px;padding:9px 12px;font-weight:700;cursor:pointer}.controls button:hover,.chapter-open:hover{background:#eef6ff;text-decoration:none}
.shell{max-width:1240px;margin:auto;padding:0 16px 30px;display:grid;grid-template-columns:310px minmax(0,1fr);gap:22px}.chapters{position:sticky;top:80px;align-self:start;max-height:78vh;overflow:auto;background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px}.chapters h2{font-size:1.1rem;margin:4px 0 8px}.close-drawer{display:none}.chapter-search label{font-size:.9rem;font-weight:700}.chapter-search input{width:100%;margin:5px 0 9px;padding:10px;border:1px solid #cad5df;border-radius:8px}.chapter-list{padding-left:23px;margin:0}.chapter-list li{margin:7px 0}.chapter-list a[aria-current=page]{font-weight:700;color:#0a4777}
.content{min-width:0;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:22px;box-shadow:0 8px 25px #17212d0a}.content h2{font-size:1.7rem;line-height:1.25}.content h3{margin-top:24px}.lesson-intro,.concept,.explain,.mistakes,.practice,.summary,.legal-note{padding:14px 16px;border-radius:11px;background:#f5f8fb;border-left:4px solid #8ab9e2;margin:15px 0}.legal-note{background:#fff9e3;border-left-color:#d5aa00}
.code-wrap{margin:16px 0}.code-title{font-weight:700;margin-bottom:5px}.code-box,.output-box{max-width:100%;overflow:auto;white-space:pre;background:var(--code);color:#f8fafc;padding:15px;border-radius:10px;direction:ltr;text-align:left;font:14px/1.55 ui-monospace,SFMono-Regular,Consolas,monospace}.output-box{background:#182337}
.step-list{padding-left:24px}.pager{display:flex;justify-content:space-between;gap:12px;border-top:1px solid var(--line);padding-top:18px;margin-top:22px}.pager a{font-weight:700}
.index-course-list{columns:2;column-gap:30px}.index-course-list li{break-inside:avoid;margin:5px 0}.course-map-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:15px}.part-card{background:#f6f9fc;border:1px solid var(--line);border-radius:12px;padding:14px}.part-card h3{margin-top:0}
.site-footer{background:var(--ink);color:#fff;margin-top:25px}.footer-in{max-width:1240px;margin:auto;padding:25px 16px}.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1.4fr;gap:22px}.site-footer h2{font-size:1.1rem}.site-footer a{color:#d8ebff}.socials{display:flex;flex-wrap:wrap;gap:9px}.socials a{display:inline-flex;align-items:center;gap:6px;border:1px solid #ffffff35;border-radius:8px;padding:7px 9px}.socials svg{width:19px;height:19px}.copy{border-top:1px solid #ffffff26;margin-top:18px;padding-top:14px;font-size:.88rem;color:#cbd5df}
.go-top{position:fixed;right:16px;bottom:16px;z-index:35;width:44px;height:44px;border:0;border-radius:50%;background:var(--blue);color:#fff;font-size:20px;box-shadow:0 3px 12px #0003;cursor:pointer}
html.rtl{direction:rtl}html.rtl .code-box,html.rtl .output-box{direction:ltr;text-align:left}html.rtl .lesson-intro,html.rtl .concept,html.rtl .explain,html.rtl .mistakes,html.rtl .practice,html.rtl .summary,html.rtl .legal-note{border-left:0;border-right:4px solid #8ab9e2}
body.night{--ink:#e8eef5;--muted:#c3ccd5;--line:#374151;--bg:#10151d;--card:#1b2430;--blue2:#16283a;--yellow:#332d16}body.night .topbar,body.night .site-footer{background:#0c1118}body.night .chapters,body.night .controls button,body.night .chapter-open,body.night .chapter-search input{background:#1b2430;color:#e8eef5;border-color:#374151}body.night .lesson-intro,body.night .concept,body.night .explain,body.night .mistakes,body.night .practice,body.night .summary{background:#222d3a}body.night .translator-wrap{background:#18212b}
.drawer-overlay{display:none}
@media(max-width:920px){
 .topbar-in{flex-wrap:wrap}.site-toggle{display:block}.site-nav{display:none;width:100%;margin:0}.site-nav.open{display:block}.site-nav ul{flex-direction:column;align-items:stretch}.site-nav a{padding:10px}
 .shell{grid-template-columns:1fr}.chapters{position:fixed;left:-100%;top:0;bottom:0;width:min(88vw,370px);max-height:none;border-radius:0;z-index:70;transition:left .25s ease}.chapters.open{left:0}.close-drawer{display:block;float:right;border:0;background:transparent;font-size:20px}.drawer-overlay.open{display:block;position:fixed;inset:0;background:#0009;z-index:60}
 .footer-grid,.course-map-grid{grid-template-columns:1fr}.index-course-list{columns:1}
}
@media(max-width:600px){.brand img{width:190px}.hero-in{padding:19px 11px}.controls,.shell{padding-left:10px;padding-right:10px}.content{padding:14px}.translator-in{padding-left:10px;padding-right:10px}.pager{flex-direction:column}}
@media print{.topbar,.translator-wrap,.controls,.chapters,.drawer-overlay,.site-footer,.go-top{display:none!important}.shell{display:block;max-width:none}.content{border:0;box-shadow:none}}

.footer-logo{display:block;width:min(230px,100%);height:auto;margin:0 0 12px}.socials a{width:38px;height:38px;justify-content:center;padding:0}.socials a span{display:none}.socials svg{width:20px;height:20px;display:block}.copy{text-align:center}