/* =========================================================
   EconLearn – main stylesheet
   ========================================================= */
:root{
  --navy:#16325c; --blue:#1f5fa8; --blue-l:#e8f0fb; --green:#2a9d6c; --green-l:#e3f4ec;
  --orange:#f08c2e; --orange-l:#fdf0e2; --red:#d4475c; --red-l:#fbe8eb; --purple:#7b4fb0; --purple-l:#f2ecf9;
  --gold:#f5b301; --silver:#a3acb9; --bronze:#c47a3a;
  --bg:#f4f6fb; --card:#ffffff; --text:#1f2937; --muted:#6b7280; --line:#e3e8f0; --soft:#f8fafc;
  --shadow:0 1px 2px rgba(16,24,40,.05),0 6px 18px rgba(16,24,40,.06);
  --radius:14px; --read-size:17px;
  --font:"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif;
}
[data-theme="dark"]{
  --bg:#0e1626; --card:#16213a; --text:#e6ebf4; --muted:#9aa6bb; --line:#26344f; --soft:#1a2742;
  --blue-l:#1b2c4a; --green-l:#163a2f; --orange-l:#3a2a19; --red-l:#3c1f27; --purple-l:#2b2240;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 6px 18px rgba(0,0,0,.25);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body{margin:0;font-family:var(--font);background:var(--bg);color:var(--text);font-size:16px;line-height:1.6;
  overflow-x:hidden;touch-action:manipulation;padding-bottom:env(safe-area-inset-bottom)}
img,svg{max-width:100%;height:auto}
a{color:var(--blue);text-decoration:none}
[data-theme="dark"] a{color:#7fb3ff}
a:hover{text-decoration:underline}
h1,h2,h3,h4{line-height:1.25;color:var(--text);margin:0 0 .5em}
h1{font-size:clamp(1.6rem,4vw,2.4rem)}
p{margin:0 0 1em}
.wrap{max-width:1180px;margin:0 auto;padding:0 16px}
.muted{color:var(--muted)} .small{font-size:.88rem}
.center{text-align:center}
.skip{position:absolute;left:-999px}.skip:focus{left:10px;top:10px;z-index:99;background:#fff;padding:8px}
.hide{display:none!important}

/* ---------- forms: always dark, clearly visible text ---------- */
input,select,textarea,button{font:inherit}
input[type=text],input[type=search],input[type=password],input[type=email],input[type=number],input[type=datetime-local],input[type=url],select,textarea{
  width:100%;padding:11px 13px;border:1.5px solid #c9d3e2;border-radius:10px;background:#ffffff;color:#111827;
  font-size:16px;line-height:1.4;outline:none;-webkit-appearance:none;appearance:none}
select{background-image:linear-gradient(45deg,transparent 50%,#555 50%),linear-gradient(135deg,#555 50%,transparent 50%);
  background-position:calc(100% - 18px) 50%,calc(100% - 13px) 50%;background-size:5px 5px;background-repeat:no-repeat;padding-right:34px}
input::placeholder,textarea::placeholder{color:#7b8494;opacity:1}
input:focus,select:focus,textarea:focus{border-color:var(--blue);box-shadow:0 0 0 3px rgba(31,95,168,.18)}
textarea{min-height:120px;resize:vertical}
label{display:block;font-weight:600;margin:0 0 6px;font-size:.95rem}
.field{margin-bottom:16px}
.field small{display:block;color:var(--muted);margin-top:4px}
.check{display:flex;gap:8px;align-items:center;font-weight:500}
.check input{width:18px;height:18px}

/* ---------- buttons ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:11px 18px;border-radius:11px;border:0;
  font-weight:700;cursor:pointer;text-decoration:none!important;line-height:1.2;transition:transform .08s,filter .15s,background .15s;
  background:var(--soft);color:var(--text);border:1.5px solid var(--line)}
.btn:hover{filter:brightness(1.05)}
.btn:active{transform:scale(.98)}
.btn-primary{background:var(--blue);color:#fff!important;border-color:var(--blue)}
.btn-green{background:var(--green);color:#fff!important;border-color:var(--green)}
.btn-orange{background:var(--orange);color:#fff!important;border-color:var(--orange)}
.btn-red{background:var(--red);color:#fff!important;border-color:var(--red)}
.btn-purple{background:var(--purple);color:#fff!important;border-color:var(--purple)}
.btn-navy{background:var(--navy);color:#fff!important;border-color:var(--navy)}
.btn-ghost{background:transparent}
.btn-sm{padding:7px 12px;font-size:.88rem;border-radius:9px}
.btn-lg{padding:14px 24px;font-size:1.05rem}
.btn-block{width:100%}
.btn[disabled]{opacity:.55;cursor:not-allowed}
.btn-row{display:flex;flex-wrap:wrap;gap:10px}
.icon-btn{width:40px;height:40px;border-radius:10px;border:0;background:transparent;color:inherit;cursor:pointer;font-size:19px;
  display:inline-flex;align-items:center;justify-content:center;text-decoration:none!important}
.icon-btn:hover{background:rgba(255,255,255,.12)}

/* ---------- alerts ---------- */
.alert{padding:12px 16px;border-radius:12px;margin:12px 0;font-weight:500;border:1.5px solid}
.alert-success{background:var(--green-l);border-color:var(--green);color:var(--text)}
.alert-error{background:var(--red-l);border-color:var(--red);color:var(--text)}
.alert-info{background:var(--blue-l);border-color:var(--blue);color:var(--text)}
.alert-warn{background:var(--orange-l);border-color:var(--orange);color:var(--text)}
.flash-wrap{padding-top:12px}

/* ---------- header ---------- */
.topbar{position:sticky;top:0;z-index:50;background:var(--navy);color:#fff;box-shadow:0 2px 10px rgba(0,0,0,.15)}
.topbar-in{display:flex;align-items:center;gap:10px;height:58px}
.brand{display:flex;align-items:center;gap:9px;color:#fff!important;font-weight:800;font-size:1.15rem;text-decoration:none!important;white-space:nowrap;min-width:0}
.brand img{border-radius:9px;flex:none}
.brand span{overflow:hidden;text-overflow:ellipsis}
.mainnav{display:flex;gap:2px;margin-left:16px;flex:1}
.mainnav a{color:#cfdbef;padding:8px 12px;border-radius:9px;font-weight:600;font-size:.95rem;text-decoration:none}
.mainnav a:hover,.mainnav a.on{background:rgba(255,255,255,.12);color:#fff}
.top-actions{display:flex;align-items:center;gap:4px;margin-left:auto}
.avatar-link{display:flex;align-items:center;gap:6px;text-decoration:none!important;padding:3px 6px;border-radius:10px}
.avatar-link:hover{background:rgba(255,255,255,.12)}
.xp-pill{background:rgba(255,255,255,.15);color:#fff;border-radius:20px;padding:2px 9px;font-size:.8rem;font-weight:700}
.menu-btn{display:none}
.show-xs{display:none!important}
.searchbar{display:none;background:#0f2546;padding:10px 0}
.searchbar.open{display:block}
.searchbar-in{display:flex;gap:8px}
.avatar{width:42px;height:42px;border-radius:50%;display:inline-flex;align-items:center;justify-content:center;color:#fff;font-weight:800;
  flex:none;font-size:.95rem;letter-spacing:.5px}
.avatar.sm{width:32px;height:32px;font-size:.78rem}
.avatar.lg{width:72px;height:72px;font-size:1.5rem}

/* ---------- drawer (mobile menu) ---------- */
.drawer{position:fixed;inset:0;z-index:80;background:rgba(5,12,25,.5);opacity:0;pointer-events:none;transition:opacity .2s}
.drawer.open{opacity:1;pointer-events:auto}
.drawer-panel{position:absolute;top:0;left:0;bottom:0;width:min(300px,86vw);background:var(--card);overflow-y:auto;
  transform:translateX(-100%);transition:transform .22s;padding:10px 10px 30px}
.drawer.open .drawer-panel{transform:none}
.drawer-head{display:flex;justify-content:space-between;align-items:center;padding:6px 8px 10px;font-size:1.1rem}
.drawer-panel>a{display:flex;align-items:center;gap:12px;padding:11px 12px;border-radius:10px;color:var(--text);font-weight:600;text-decoration:none}
.drawer-panel>a>span:first-child{width:24px;text-align:center;flex:none}
.drawer-user>span.avatar{width:42px!important}
.drawer-panel>a.on,.drawer-panel>a:hover{background:var(--blue-l)}
.drawer-sep{font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);padding:14px 12px 4px;font-weight:700}
.drawer-user{background:var(--blue-l);margin-bottom:8px}
.drawer-user span:last-child{display:flex;flex-direction:column;line-height:1.3}
.drawer-user small{color:var(--muted);font-weight:500}

/* ---------- layout pieces ---------- */
.main{min-height:60vh}
.section{padding:34px 0}
.section-head{display:flex;justify-content:space-between;align-items:flex-end;gap:12px;margin-bottom:18px;flex-wrap:wrap}
.section-head h2{margin:0;font-size:1.5rem}
.page-head{background:linear-gradient(135deg,var(--navy),var(--blue));color:#fff;padding:28px 0 30px}
.page-head h1{color:#fff;margin:0 0 6px}
.page-head p{color:#d6e2f5;margin:0;max-width:720px}
.crumbs{font-size:.85rem;color:#b9cbe6;margin-bottom:6px}
.crumbs a{color:#fff}
.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--line);padding:20px}
.card h3{margin-top:0}
.grid{display:grid;gap:18px}
.g2{grid-template-columns:repeat(2,minmax(0,1fr))}
.g3{grid-template-columns:repeat(3,minmax(0,1fr))}
.g4{grid-template-columns:repeat(4,minmax(0,1fr))}
.tag{display:inline-block;padding:2px 10px;border-radius:20px;font-size:.78rem;font-weight:700;background:var(--blue-l);color:var(--blue)}
[data-theme="dark"] .tag{color:#9cc2ff}
.tag.green{background:var(--green-l);color:var(--green)} .tag.orange{background:var(--orange-l);color:#b8620e}
.tag.red{background:var(--red-l);color:var(--red)} .tag.purple{background:var(--purple-l);color:var(--purple)}
.pbar{height:10px;background:var(--line);border-radius:20px;overflow:hidden}
.pbar>i{display:block;height:100%;background:linear-gradient(90deg,var(--green),#45c08a);border-radius:20px;transition:width .4s}
.empty{padding:30px;text-align:center;color:var(--muted)}

/* ---------- hero ---------- */
.hero{background:radial-gradient(1200px 400px at 80% -10%,#2a5c9e 0%,transparent 60%),linear-gradient(140deg,#0f2546,#16325c 55%,#1f5fa8);color:#fff;padding:46px 0 54px;overflow:hidden}
.hero-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:30px;align-items:center}
.hero h1{color:#fff;font-size:clamp(1.8rem,4.4vw,3rem);margin-bottom:14px}
.hero h1 em{font-style:normal;color:#ffd166}
.hero p.lead{font-size:1.12rem;color:#d6e2f5;max-width:600px}
.hero .kicker{display:inline-block;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.2);padding:5px 12px;border-radius:30px;font-size:.85rem;margin-bottom:14px;font-weight:600}
.hero-art img{width:100%;filter:drop-shadow(0 20px 30px rgba(0,0,0,.25))}
.hero .btn-row{margin-top:22px}
.hero .btn-ghost{color:#fff;border-color:rgba(255,255,255,.4)}
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-top:-30px;position:relative}
.stat{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:16px;text-align:center;border:1px solid var(--line)}
.stat b{display:block;font-size:1.7rem;color:var(--blue);line-height:1.1}
[data-theme="dark"] .stat b{color:#7fb3ff}
.stat span{color:var(--muted);font-size:.88rem;font-weight:600}

/* ---------- learning-mode cards ---------- */
.modes{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px}
.mode{display:flex;flex-direction:column;gap:6px;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px;
  box-shadow:var(--shadow);color:var(--text)!important;text-decoration:none!important;transition:transform .15s,box-shadow .15s;position:relative;overflow:hidden}
.mode:hover{transform:translateY(-3px);box-shadow:0 10px 26px rgba(16,24,40,.12)}
.mode .mi{width:48px;height:48px;border-radius:13px;display:flex;align-items:center;justify-content:center;font-size:24px;color:#fff;margin-bottom:6px}
.mode b{font-size:1.05rem}
.mode span{color:var(--muted);font-size:.9rem;line-height:1.45}
.bg-blue{background:var(--blue)} .bg-green{background:var(--green)} .bg-orange{background:var(--orange)} .bg-red{background:var(--red)}
.bg-purple{background:var(--purple)} .bg-navy{background:var(--navy)}

/* ---------- lesson cards ---------- */
.lesson-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}
.lcard{background:var(--card);border-radius:var(--radius);overflow:hidden;border:1px solid var(--line);box-shadow:var(--shadow);display:flex;flex-direction:column;
  color:var(--text)!important;text-decoration:none!important;transition:transform .15s}
.lcard:hover{transform:translateY(-3px)}
.lcard .cov{aspect-ratio:20/9;background:#e9eef6;position:relative;overflow:hidden}
.lcard .cov img{width:100%;height:100%;object-fit:cover;display:block}
.lcard .done{position:absolute;top:10px;right:10px;background:var(--green);color:#fff;border-radius:20px;padding:3px 10px;font-size:.78rem;font-weight:800}
.lcard .body{padding:14px 16px 16px;display:flex;flex-direction:column;gap:6px;flex:1}
.lcard h3{font-size:1.06rem;margin:0}
.lcard p{color:var(--muted);font-size:.9rem;margin:0;flex:1}
.lcard .meta{display:flex;gap:10px;font-size:.8rem;color:var(--muted);font-weight:600;margin-top:6px}
.lesson-list{display:flex;flex-direction:column;gap:10px}
.lrow{display:flex;align-items:center;gap:14px;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 14px;color:var(--text)!important;text-decoration:none!important}
.lrow:hover{border-color:var(--blue)}
.lnum{width:44px;height:44px;border-radius:12px;background:var(--blue-l);color:var(--blue);font-weight:800;display:flex;align-items:center;justify-content:center;flex:none}
.lrow.isdone .lnum{background:var(--green);color:#fff}
.lrow .lt{flex:1;min-width:0}
.lrow .lt b{display:block}
.lrow .lt small{color:var(--muted)}

/* ---------- lesson page ---------- */
.lesson-hero{position:relative;color:#fff;background:var(--navy)}
.lesson-hero{overflow:hidden}
.lesson-hero .cov{position:absolute;top:0;right:0;bottom:0;width:62%;background-size:cover;background-position:center right;opacity:.75;-webkit-mask-image:linear-gradient(90deg,transparent,#000 70%);mask-image:linear-gradient(90deg,transparent,#000 70%)}
@media(max-width:600px){.lesson-hero .cov{width:100%;opacity:.25}}
.lesson-hero .in{position:relative;padding:34px 16px 30px}
.lesson-hero h1{color:#fff;margin:0 0 8px}
.lesson-hero p{color:#e3ebf7;margin:0}
.lesson-hero .num{display:inline-flex;align-items:center;justify-content:center;min-width:52px;height:52px;padding:0 10px;border-radius:14px;background:var(--orange);font-size:1.5rem;font-weight:900;margin-bottom:12px}
.lesson-meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
.lesson-meta span{background:rgba(255,255,255,.15);padding:4px 11px;border-radius:20px;font-size:.84rem;font-weight:600}
.read-progress{position:fixed;top:0;left:0;height:3px;background:var(--orange);z-index:60;width:0}
.lesson-layout{display:grid;grid-template-columns:250px minmax(0,1fr);gap:28px;padding:26px 16px 40px;max-width:1180px;margin:0 auto}
.toc{position:sticky;top:76px;align-self:start;max-height:calc(100vh - 90px);overflow:auto}
.toc .card{padding:14px}
.toc b{display:block;margin-bottom:6px;font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted)}
.toc a{display:block;padding:6px 8px;border-radius:8px;color:var(--text);font-size:.9rem;line-height:1.35;text-decoration:none}
.toc a:hover,.toc a.on{background:var(--blue-l);color:var(--blue)}
.toolbar{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:18px;align-items:center}
.toolbar .btn{padding:8px 12px;font-size:.88rem}
.content{font-size:var(--read-size);background:var(--card);border-radius:var(--radius);border:1px solid var(--line);box-shadow:var(--shadow);padding:26px 30px}
.content h2{font-size:1.45em;color:var(--blue);margin:1.6em 0 .6em;scroll-margin-top:80px;padding-bottom:6px;border-bottom:2px solid var(--line)}
[data-theme="dark"] .content h2{color:#7fb3ff}
.content h2:first-child{margin-top:0}
.content h3{font-size:1.15em;color:var(--navy);margin:1.4em 0 .5em}
[data-theme="dark"] .content h3{color:#c7d6ef}
.content ul,.content ol{padding-left:1.4em;margin:0 0 1em}
.content li{margin-bottom:.4em}
.box{border-radius:12px;margin:18px 0;overflow:hidden;border:1.5px solid}
.box-h{padding:8px 16px;font-weight:800;color:#fff;font-size:.82em;text-transform:uppercase;letter-spacing:.06em}
.box-b{padding:12px 16px}
.box-b p:last-child,.box-b ul:last-child,.box-b ol:last-child{margin-bottom:0}
.box-def{border-color:var(--blue)} .box-def .box-h{background:var(--blue)} .box-def .box-b{background:var(--blue-l)}
.box-ex,.box-simple{border-color:var(--green)} .box-ex .box-h,.box-simple .box-h{background:var(--green)} .box-ex .box-b,.box-simple .box-b{background:var(--green-l)}
.box-tip{border-color:var(--orange)} .box-tip .box-h{background:var(--orange)} .box-tip .box-b{background:var(--orange-l)}
.box-remember,.box-trick{border-color:var(--red)} .box-remember .box-h,.box-trick .box-h{background:var(--red)} .box-remember .box-b,.box-trick .box-b{background:var(--red-l)}
.box-read{border-color:var(--purple)} .box-read .box-h{background:var(--purple)} .box-read .box-b{background:var(--purple-l)}
.box-read .box-h::before{content:"🔍 "}
.box-try{border-color:var(--navy);border-style:dashed} .box-try .box-h{background:var(--navy)} .box-try .box-b{background:var(--soft)}
.box-try .box-h::before{content:"🧪 "}
.fig{margin:22px 0 6px;text-align:center}
.fig img{width:100%;max-width:760px;border-radius:12px;border:1px solid var(--line);background:#fff;cursor:zoom-in}
.fig figcaption{font-size:.85em;color:var(--muted);font-style:italic;margin-top:6px}
.tbl{overflow-x:auto;margin:14px 0 20px;border-radius:12px;border:1px solid var(--line);-webkit-overflow-scrolling:touch}
.tbl table{border-collapse:collapse;width:100%;min-width:480px;font-size:.92em}
.tbl th{background:var(--blue);color:#fff;text-align:left;padding:10px 12px;font-weight:700}
.tbl td{padding:9px 12px;border-top:1px solid var(--line);vertical-align:top}
.tbl tbody tr:nth-child(even) td{background:var(--soft)}
.tbl table.green th{background:var(--green)} .tbl table.orange th{background:var(--orange)} .tbl table.purple th{background:var(--purple)}
.tbl table.warn th{background:var(--red)} .tbl table.cheat th{background:var(--navy)}
.tbl table.schedule{min-width:420px} .tbl table.schedule td,.tbl table.schedule th{text-align:center}
.tbl table.schedule td:first-child{font-weight:700;text-align:left}
.tbl table.eq tbody tr:nth-child(3) td{background:var(--purple-l)}
.tbl table.proscons th:first-child{background:var(--green)} .tbl table.proscons th:last-child{background:var(--red)}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.sticky-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin:14px 0 20px}
.sticky{background:#fff6c8;color:#3b3200;padding:14px;border-radius:4px 4px 14px 4px;box-shadow:0 4px 10px rgba(0,0,0,.08);font-size:.93em;transform:rotate(-.6deg)}
.sticky:nth-child(even){background:#dff3ff;color:#0d3047;transform:rotate(.6deg)}
.sticky:nth-child(3n){background:#e6f8e2;color:#173b10}
.keypoints{margin-top:24px}
.keypoints ul{list-style:none;padding:0;margin:0}
.keypoints li{padding:8px 0 8px 32px;position:relative;border-bottom:1px dashed var(--line)}
.keypoints li:last-child{border:0}
.keypoints li::before{content:"✔";position:absolute;left:4px;top:8px;width:20px;height:20px;border-radius:50%;background:var(--green);color:#fff;font-size:.72rem;display:flex;align-items:center;justify-content:center}
.lesson-nav{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:20px}
.lesson-nav a{display:block;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:14px;color:var(--text)!important;text-decoration:none!important}
.lesson-nav a:hover{border-color:var(--blue)}
.lesson-nav small{color:var(--muted);display:block}
.lesson-nav .next{text-align:right}
.complete-box{display:flex;gap:14px;align-items:center;justify-content:space-between;flex-wrap:wrap;margin-top:20px;background:linear-gradient(135deg,var(--green-l),var(--blue-l))}
.notes-box textarea{min-height:140px}
.note-status{font-size:.82rem;color:var(--muted)}

/* ---------- lightbox ---------- */
.lightbox{position:fixed;inset:0;background:rgba(5,10,20,.88);z-index:90;display:none;align-items:center;justify-content:center;padding:14px}
.lightbox.open{display:flex}
.lightbox img{max-width:100%;max-height:88vh;background:#fff;border-radius:10px}
.lightbox button{position:absolute;top:12px;right:12px;background:#fff;border:0;border-radius:50%;width:42px;height:42px;font-size:20px;cursor:pointer}

/* ---------- quiz ---------- */
.quiz-wrap{max-width:820px;margin:0 auto}
.quiz-top{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:12px;flex-wrap:wrap}
.timer{font-weight:800;font-size:1.1rem;background:var(--card);border:1px solid var(--line);padding:6px 14px;border-radius:30px;font-variant-numeric:tabular-nums}
.timer.low{color:var(--red);border-color:var(--red)}
.qcard{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px}
.qnum{font-size:.85rem;font-weight:800;color:var(--purple);text-transform:uppercase;letter-spacing:.05em}
.qtext{font-size:1.18rem;font-weight:700;margin:6px 0 16px;line-height:1.45}
.opts{display:flex;flex-direction:column;gap:10px}
.opt{display:flex;gap:12px;align-items:flex-start;text-align:left;width:100%;padding:13px 14px;border-radius:12px;border:2px solid var(--line);background:var(--soft);
  color:var(--text);cursor:pointer;font-size:1rem;line-height:1.45;transition:border-color .12s,background .12s}
.opt:hover{border-color:var(--blue)}
.opt .k{flex:none;width:30px;height:30px;border-radius:9px;background:var(--card);border:1.5px solid var(--line);display:flex;align-items:center;justify-content:center;font-weight:800;text-transform:uppercase}
.opt.sel{border-color:var(--blue);background:var(--blue-l)} .opt.sel .k{background:var(--blue);color:#fff;border-color:var(--blue)}
.opt.right{border-color:var(--green);background:var(--green-l)} .opt.right .k{background:var(--green);color:#fff;border-color:var(--green)}
.opt.wrong{border-color:var(--red);background:var(--red-l)} .opt.wrong .k{background:var(--red);color:#fff;border-color:var(--red)}
.opt[disabled]{cursor:default}
.explain{margin-top:14px;padding:12px 14px;border-radius:12px;background:var(--purple-l);border-left:4px solid var(--purple);display:none}
.explain.show{display:block}
.qnav{display:flex;justify-content:space-between;gap:10px;margin-top:16px;flex-wrap:wrap}
.dots{display:flex;flex-wrap:wrap;gap:6px;margin:14px 0}
.dots button{width:32px;height:32px;border-radius:8px;border:1.5px solid var(--line);background:var(--card);color:var(--text);font-weight:700;font-size:.8rem;cursor:pointer}
.dots button.ans{background:var(--blue);color:#fff;border-color:var(--blue)}
.dots button.cur{outline:3px solid var(--orange)}
.dots button.ok{background:var(--green);border-color:var(--green);color:#fff}
.dots button.no{background:var(--red);border-color:var(--red);color:#fff}
.result-hero{text-align:center;padding:26px}
.score-ring{width:150px;height:150px;border-radius:50%;margin:0 auto 14px;display:flex;align-items:center;justify-content:center;flex-direction:column;
  background:conic-gradient(var(--green) calc(var(--p)*1%),var(--line) 0)}
.score-ring>div{width:120px;height:120px;border-radius:50%;background:var(--card);display:flex;flex-direction:column;align-items:center;justify-content:center}
.score-ring b{font-size:2rem;line-height:1}
.review-item{border:1px solid var(--line);border-radius:12px;padding:14px;margin-bottom:10px;background:var(--card)}
.review-item.ok{border-left:5px solid var(--green)} .review-item.no{border-left:5px solid var(--red)}
.review-item .ans{font-size:.93rem;margin-top:6px}
.qc-item{margin-bottom:16px}

/* ---------- flashcards ---------- */
.flash-stage{perspective:1200px;max-width:640px;margin:0 auto}
.flashcard{position:relative;height:330px;cursor:pointer;transform-style:preserve-3d;transition:transform .5s}
.flashcard.flip{transform:rotateY(180deg)}
.face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;border-radius:20px;padding:26px;display:flex;flex-direction:column;
  align-items:center;justify-content:center;text-align:center;box-shadow:0 14px 34px rgba(16,24,40,.15)}
.face.front{background:linear-gradient(140deg,var(--navy),var(--blue));color:#fff}
.face.front h2{color:#fff;font-size:clamp(1.4rem,4vw,2rem);margin:10px 0}
.face.back{background:var(--card);border:2px solid var(--blue);transform:rotateY(180deg);overflow:auto}
.face.back .m{font-size:1.15rem;font-weight:600}
.face.back .x{color:var(--muted);margin-top:10px}
.face small{opacity:.8}
.flash-controls{display:flex;justify-content:center;gap:10px;margin-top:18px;flex-wrap:wrap}
.flash-count{text-align:center;margin-top:10px;color:var(--muted);font-weight:600}
.filters{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin-bottom:18px}
.chip{padding:7px 14px;border-radius:30px;border:1.5px solid var(--line);background:var(--card);color:var(--text);font-weight:600;cursor:pointer;font-size:.9rem}
.chip.on{background:var(--blue);border-color:var(--blue);color:#fff}

/* ---------- match game ---------- */
.match-board{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.match-col{display:flex;flex-direction:column;gap:10px}
.mtile{padding:13px 14px;border-radius:12px;border:2px solid var(--line);background:var(--card);color:var(--text);cursor:pointer;text-align:left;font-size:.95rem;line-height:1.4;min-height:58px;transition:all .15s}
.mtile.term{font-weight:800;text-align:center}
.mtile.sel{border-color:var(--blue);background:var(--blue-l)}
.mtile.done{border-color:var(--green);background:var(--green-l);opacity:.65;cursor:default}
.mtile.bad{border-color:var(--red);background:var(--red-l);animation:shake .35s}
@keyframes shake{25%{transform:translateX(-5px)}75%{transform:translateX(5px)}}
.game-stats{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-bottom:16px}
.game-stats span{background:var(--card);border:1px solid var(--line);border-radius:30px;padding:6px 14px;font-weight:700}

/* ---------- graph lab / simulator ---------- */
.lab{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(0,1fr);gap:20px;align-items:start}
.lab-chart{background:#fff;border-radius:var(--radius);border:1px solid var(--line);box-shadow:var(--shadow);padding:8px}
.lab-chart svg{width:100%;height:auto;display:block}
.ctrl{margin-bottom:16px}
.ctrl label{display:flex;justify-content:space-between}
.ctrl output{font-weight:800;color:var(--blue)}
input[type=range]{width:100%;accent-color:var(--blue);height:30px}
.readout{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:14px 0}
.readout div{background:var(--soft);border:1px solid var(--line);border-radius:12px;padding:10px;text-align:center}
.readout b{display:block;font-size:1.3rem}
.readout small{color:var(--muted);font-weight:600}
.lab-msg{padding:12px 14px;border-radius:12px;background:var(--purple-l);border-left:4px solid var(--purple);font-weight:500}
.seg{display:flex;flex-wrap:wrap;gap:6px}
.seg button{flex:1;min-width:90px;padding:9px;border-radius:10px;border:1.5px solid var(--line);background:var(--card);color:var(--text);font-weight:700;cursor:pointer}
.seg button.on{background:var(--blue);border-color:var(--blue);color:#fff}
.predict{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;margin:14px 0}
.predict .seg button{min-width:0}
.event-card{background:linear-gradient(135deg,var(--navy),var(--purple));color:#fff;border-radius:var(--radius);padding:18px 20px;margin-bottom:14px}
.event-card small{opacity:.85;font-weight:700;text-transform:uppercase;letter-spacing:.05em}
.event-card h3{color:#fff;margin:6px 0 0;font-size:1.25rem}

/* ---------- leaderboard ---------- */
.live{display:inline-flex;align-items:center;gap:7px;font-weight:700;font-size:.88rem;color:var(--green)}
.live i{width:10px;height:10px;border-radius:50%;background:#22c55e;box-shadow:0 0 0 0 rgba(34,197,94,.6);animation:pulse 1.6s infinite}
@keyframes pulse{70%{box-shadow:0 0 0 10px rgba(34,197,94,0)}100%{box-shadow:0 0 0 0 rgba(34,197,94,0)}}
.comp-banner{background:linear-gradient(120deg,#3b1d6e,var(--purple) 50%,var(--red));color:#fff;border-radius:var(--radius);padding:20px 22px;display:flex;gap:16px;align-items:center;justify-content:space-between;flex-wrap:wrap}
.comp-banner h2{color:#fff;margin:0 0 4px}
.countdown{display:flex;gap:8px}
.countdown div{background:rgba(255,255,255,.15);border-radius:12px;padding:8px 10px;text-align:center;min-width:58px}
.countdown b{display:block;font-size:1.4rem;line-height:1.1;font-variant-numeric:tabular-nums}
.countdown small{font-size:.7rem;text-transform:uppercase;opacity:.85}
.tabs{display:flex;gap:6px;flex-wrap:wrap;margin:18px 0 14px}
.tabs button,.tabs a{padding:9px 16px;border-radius:30px;border:1.5px solid var(--line);background:var(--card);color:var(--text);font-weight:700;cursor:pointer;text-decoration:none!important}
.tabs .on{background:var(--navy);border-color:var(--navy);color:#fff}
.podium{display:grid;grid-template-columns:1fr 1.1fr 1fr;gap:12px;align-items:end;margin:10px 0 20px}
.pod{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);text-align:center;padding:16px 10px;box-shadow:var(--shadow);position:relative}
.pod .medal{font-size:2rem}
.pod .avatar{margin:6px auto}
.pod b{display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pod .sc{font-size:1.25rem;font-weight:900;color:var(--blue)}
[data-theme="dark"] .pod .sc{color:#7fb3ff}
.pod.p1{border:2px solid var(--gold);padding-top:26px;background:linear-gradient(180deg,#fff8dc,var(--card) 60%)}
[data-theme="dark"] .pod.p1{background:linear-gradient(180deg,#3d3413,var(--card) 60%)}
.pod.p2{border:2px solid var(--silver)} .pod.p3{border:2px solid var(--bronze)}
.lb{display:flex;flex-direction:column;gap:8px}
.lbrow{display:grid;grid-template-columns:44px 44px minmax(0,1fr) auto;gap:10px;align-items:center;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px 14px;transition:background .6s}
.lbrow .rk{font-weight:900;font-size:1.05rem;text-align:center;color:var(--muted)}
.lbrow.r1 .rk{color:var(--gold)} .lbrow.r2 .rk{color:var(--silver)} .lbrow.r3 .rk{color:var(--bronze)}
.lbrow .nm b{display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.lbrow .nm small{color:var(--muted);display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.lbrow .pts{text-align:right;font-weight:900;font-size:1.05rem}
.lbrow .pts small{display:block;color:var(--muted);font-weight:600;font-size:.78rem}
.lbrow.me{border:2px solid var(--orange);background:var(--orange-l)}
.lbrow.flash{background:#fff3b0}
[data-theme="dark"] .lbrow.flash{background:#4a4210}
.lb-meta{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap;color:var(--muted);font-size:.88rem}

/* ---------- dashboard ---------- */
.profile{display:flex;gap:18px;align-items:center;flex-wrap:wrap}
.level{display:flex;gap:12px;align-items:center}
.level .ic{font-size:2.2rem}
.table{width:100%;border-collapse:collapse;font-size:.93rem}
.table th,.table td{padding:9px 10px;border-bottom:1px solid var(--line);text-align:left}
.table th{color:var(--muted);font-size:.8rem;text-transform:uppercase;letter-spacing:.05em}
.table-wrap{overflow-x:auto}

/* ---------- auth ---------- */
.auth{max-width:440px;margin:34px auto;padding:0 16px}
.auth .card{padding:26px}
.auth h1{font-size:1.6rem}

/* ---------- glossary ---------- */
.gloss{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.gterm{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:14px 16px}
.gterm b{font-size:1.05rem;color:var(--blue)}
[data-theme="dark"] .gterm b{color:#7fb3ff}
.gterm p{margin:4px 0}
.gterm .ex{color:var(--muted);font-size:.9rem}
.az{display:flex;flex-wrap:wrap;gap:4px;margin-bottom:14px}
.az a{width:32px;height:32px;display:flex;align-items:center;justify-content:center;border-radius:8px;background:var(--card);border:1px solid var(--line);font-weight:700;font-size:.85rem}
mark{background:#ffe58a;color:#222;padding:0 2px;border-radius:3px}

/* ---------- figures gallery ---------- */
.figs{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
.figs figure{margin:0;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px}
.figs img{width:100%;border-radius:8px;background:#fff;cursor:zoom-in;display:block}
.figs figcaption{font-size:.85rem;margin-top:6px}

/* ---------- announcements ---------- */
.notice{display:flex;gap:12px;padding:14px;border-radius:12px;background:var(--card);border:1px solid var(--line);margin-bottom:10px}
.notice .i{font-size:1.4rem}
.notice b{display:block}

/* ---------- footer ---------- */
.footer{background:#0f2546;color:#c7d3e6;padding:36px 0 14px;margin-top:40px}
.footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:24px}
.footer h4{color:#fff;margin-bottom:10px}
.footer a{display:block;color:#c7d3e6;padding:3px 0;font-size:.93rem}
.footer .muted{color:#9fb0cc}
.footer-brand{margin-bottom:8px}
.copy{border-top:1px solid rgba(255,255,255,.1);margin-top:24px;padding-top:14px;font-size:.85rem;color:#8ea2c2}
.tabbar{display:none}
.toast{position:fixed;left:50%;bottom:24px;transform:translateX(-50%) translateY(30px);background:#111827;color:#fff;padding:12px 18px;border-radius:12px;
  font-weight:600;z-index:95;opacity:0;pointer-events:none;transition:all .25s;max-width:90vw;text-align:center}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}

/* ---------- responsive ---------- */
@media (max-width:1024px){
  .mainnav a{padding:8px 9px;font-size:.9rem}
  .modes{grid-template-columns:repeat(2,minmax(0,1fr))}
  .lesson-grid,.figs{grid-template-columns:repeat(2,minmax(0,1fr))}
  .lesson-layout{grid-template-columns:minmax(0,1fr)}
  .toc{display:none}
  .sticky-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (max-width:860px){
  .mainnav{display:none}
  .menu-btn{display:inline-flex}
  .hero-grid,.lab{grid-template-columns:minmax(0,1fr)}
  .hero-art{max-width:420px;margin:0 auto}
  .stats{grid-template-columns:repeat(2,1fr)}
  .g3,.g4{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-grid{grid-template-columns:1fr 1fr}
  .tabbar{display:flex;position:fixed;left:0;right:0;bottom:0;z-index:60;background:var(--card);border-top:1px solid var(--line);
    padding:4px 4px calc(4px + env(safe-area-inset-bottom));box-shadow:0 -4px 14px rgba(0,0,0,.06)}
  .tabbar a{flex:1;display:flex;flex-direction:column;align-items:center;gap:1px;font-size:.7rem;font-weight:700;color:var(--muted);padding:5px 0;text-decoration:none!important;border-radius:10px}
  .tabbar a span{font-size:1.2rem;line-height:1.2}
  .tabbar a.on{color:var(--blue);background:var(--blue-l)}
  body{padding-bottom:70px}
  .toast{bottom:84px}
}
@media (max-width:600px){
  body{font-size:15px}
  :root{--read-size:16px}
  .wrap{padding:0 12px}
  .topbar-in{height:54px;gap:4px}
  .brand{font-size:1.02rem}
  .brand img{width:30px;height:30px}
  .icon-btn{width:36px;height:36px;font-size:17px}
  .hide-xs{display:none!important}
  .show-xs{display:inline-flex!important}
  .xp-pill{display:none}
  .hero{padding:30px 0 46px}
  .section{padding:24px 0}
  .g2,.g3,.g4,.gloss,.two-col,.sticky-grid,.lesson-grid,.figs{grid-template-columns:minmax(0,1fr)}
  .modes{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
  .mode{padding:14px}
  .mode .mi{width:40px;height:40px;font-size:20px}
  .mode span{font-size:.82rem}
  .content{padding:18px 15px;border-radius:12px}
  .card{padding:16px}
  .lesson-layout{padding:16px 12px 30px}
  .qcard{padding:16px}
  .qtext{font-size:1.05rem}
  .flashcard{height:300px}
  .match-board{gap:8px}
  .mtile{padding:10px;font-size:.84rem}
  .podium{gap:6px}
  .pod{padding:12px 6px}
  .pod.p1{padding-top:18px}
  .pod .avatar{width:38px;height:38px;font-size:.8rem}
  .lbrow{grid-template-columns:30px 36px minmax(0,1fr) auto;gap:8px;padding:9px 10px}
  .lbrow .avatar{width:34px;height:34px;font-size:.75rem}
  .countdown div{min-width:50px;padding:6px}
  .lesson-nav{grid-template-columns:1fr}
  .lesson-nav .next{text-align:left}
  .footer-grid{grid-template-columns:1fr}
  .readout b{font-size:1.1rem}
  .page-head{padding:22px 0}
  .searchbar-in .btn{padding:10px 12px}
}
@media print{
  .topbar,.footer,.tabbar,.toolbar,.toc,.lesson-nav,.complete-box,.notes-box,.quick-check,.read-progress{display:none!important}
  body{background:#fff;padding:0}
  .content{box-shadow:none;border:0;padding:0}
  .lesson-hero{background:#fff;color:#000}
  .lesson-hero h1,.lesson-hero p{color:#000}
}