:root{
  --bg:#f5f7fb; --surface:#ffffff; --surface2:#eef2f8; --text:#1b2533; --muted:#5d6b80; --line:#d9e0ea;
  --accent:#1f6feb; --accent-ink:#ffffff; --ok:#1a7f4b; --ok-bg:#e3f5ec; --warn:#a15c00; --warn-bg:#fff2dc;
  --err:#b42318; --err-bg:#fde8e7; --cmd-bg:#10161f; --cmd-ink:#7ee0ff; --shadow:0 1px 3px rgba(20,30,50,.08);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0f141b; --surface:#171e28; --surface2:#1f2835; --text:#e6edf5; --muted:#9aa8bb; --line:#2b3646;
    --accent:#4c8dff; --ok:#4ccb87; --ok-bg:#12301f; --warn:#f0b35a; --warn-bg:#33260f; --err:#ff8077; --err-bg:#3a1714;
    --shadow:none;
  }
}
:root[data-theme="dark"]{
  --bg:#0f141b; --surface:#171e28; --surface2:#1f2835; --text:#e6edf5; --muted:#9aa8bb; --line:#2b3646;
  --accent:#4c8dff; --ok:#4ccb87; --ok-bg:#12301f; --warn:#f0b35a; --warn-bg:#33260f; --err:#ff8077; --err-bg:#3a1714; --shadow:none;
}
*{box-sizing:border-box}
html,body{margin:0}
body{background:var(--bg);color:var(--text);font:16px/1.65 Inter,"Noto Sans Sinhala","Noto Sans Tamil",system-ui,sans-serif}
body.lang-si{font-family:"Noto Sans Sinhala",Inter,system-ui,sans-serif}
body.lang-ta{font-family:"Noto Sans Tamil",Inter,system-ui,sans-serif}
a{color:var(--accent)}
h1,h2,h3,h4{line-height:1.3;margin:.2em 0 .5em}
h1{font-size:1.9rem} h2{font-size:1.3rem} h3{font-size:1.1rem}
.muted{color:var(--muted)} .small{font-size:.86rem}
.topbar{display:flex;flex-wrap:wrap;align-items:center;gap:12px 20px;padding:10px 20px;background:var(--surface);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:5}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;color:var(--text);text-decoration:none}
.logo{background:var(--accent);color:#fff;border-radius:8px;padding:3px 7px;font-size:.8rem;letter-spacing:.5px}
.nav{display:flex;flex-wrap:wrap;gap:4px 14px;flex:1}
.nav a{color:var(--text);text-decoration:none;font-size:.95rem}
.nav a:hover{color:var(--accent)}
.langs{display:flex;border:1px solid var(--line);border-radius:999px;overflow:hidden}
.langs a{padding:4px 12px;text-decoration:none;color:var(--muted);font-size:.9rem}
.langs a.on{background:var(--accent);color:#fff}
.wrap{max-width:1280px;margin:0 auto;padding:24px 16px 48px}
.foot{text-align:center;color:var(--muted);font-size:.8rem;padding:20px 16px;border-top:1px solid var(--line)}
.btn{display:inline-block;background:var(--accent);color:var(--accent-ink);border:0;border-radius:8px;padding:10px 18px;font:inherit;font-weight:600;text-decoration:none;cursor:pointer}
.btn:hover{filter:brightness(1.08)}
.btn.small{padding:6px 12px;font-size:.9rem}
.btn.ghost{background:transparent;color:var(--accent);border:1px solid var(--accent)}
.card{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:20px;box-shadow:var(--shadow);margin-bottom:18px}
.flash{padding:10px 14px;border-radius:8px;margin:10px 0;background:var(--surface2)}
.flash.error{background:var(--err-bg);color:var(--err)} .flash.ok{background:var(--ok-bg);color:var(--ok)}
.form{max-width:460px;margin:20px auto;display:flex;flex-direction:column;gap:12px}
.form label{display:flex;flex-direction:column;gap:4px;font-weight:600;font-size:.93rem}
input,select,textarea{font:inherit;padding:9px 11px;border:1px solid var(--line);border-radius:8px;background:var(--surface);color:var(--text);font-weight:400}
.hero{display:grid;grid-template-columns:1fr 1.1fr;gap:28px;align-items:center;margin:10px 0 30px}
.hero-img{width:100%;border-radius:12px;border:1px solid var(--line)}
.lead{font-size:1.12rem}
.stages{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.stage-card{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:16px}
.stage-card ul{margin:0;padding-left:18px;color:var(--muted)}
.stage-num{display:inline-block;font-size:.78rem;font-weight:700;color:var(--accent);background:var(--surface2);border-radius:999px;padding:2px 10px;margin-right:6px}
.summary{display:flex;flex-wrap:wrap;gap:16px;justify-content:space-between;align-items:center}
.summary>div{flex:1;min-width:240px}
.bar{height:10px;background:var(--surface2);border-radius:99px;overflow:hidden}
.bar span{display:block;height:100%;background:var(--ok)}
.stage-block{margin:22px 0}
.lesson-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.lesson-card{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:16px;display:flex;flex-direction:column;gap:8px}
.lesson-card h4{margin:0}.lesson-card p{margin:0;flex:1}
.lesson-card.locked{opacity:.6}
.badge{display:inline-block;align-self:flex-start;font-size:.75rem;font-weight:700;border-radius:999px;padding:2px 10px;background:var(--surface2);color:var(--muted)}
.badge.completed{background:var(--ok-bg);color:var(--ok)} .badge.in_progress{background:var(--warn-bg);color:var(--warn)}
code.cmd{font-family:"JetBrains Mono",Consolas,monospace;background:var(--cmd-bg);color:var(--cmd-ink);padding:1px 7px;border-radius:5px;font-size:.88em;white-space:nowrap}
code.cmd.big{font-size:1rem;padding:4px 10px}
.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 380px;gap:24px;align-items:start}
.crumb{color:var(--muted);font-size:.88rem}.crumb a{text-decoration:none}
.note{background:var(--surface2);border-left:4px solid var(--accent);padding:8px 12px;border-radius:6px;font-size:.92rem}
.sec{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin:16px 0}
.sec-head{display:flex;justify-content:space-between;align-items:flex-start;gap:12px}
.listen{border:1px solid var(--line);background:var(--surface2);color:var(--text);border-radius:999px;padding:4px 12px;cursor:pointer;font:inherit;font-size:.85rem;white-space:nowrap}
.listen.playing{background:var(--accent);color:#fff}
.shot{position:relative;margin:14px 0 0}
.shot img{width:100%;border-radius:10px;border:1px solid var(--line);display:block}
.shot-tag{position:absolute;top:8px;right:8px;background:rgba(0,0,0,.6);color:#fff;font-size:.72rem;padding:2px 8px;border-radius:999px}
.shot figcaption{font-size:.88rem;color:var(--muted);margin-top:6px}
.steps li{margin:8px 0}
.cmdline{display:flex;align-items:center;flex-wrap:wrap;gap:8px;margin-top:4px}
.copy{border:1px solid var(--line);background:transparent;color:var(--muted);border-radius:6px;padding:2px 8px;cursor:pointer;font-size:.8rem}
.sample{border-left:4px solid var(--ok)}
table.cmds{width:100%;border-collapse:collapse;font-size:.93rem}
table.cmds th,table.cmds td{text-align:left;padding:7px 8px;border-bottom:1px solid var(--line);vertical-align:top}
.q{border:1px solid var(--line);border-radius:10px;margin:12px 0;padding:10px 14px}
.q legend{font-weight:600;padding:0 4px}
.opt{display:flex;gap:8px;align-items:flex-start;padding:4px 0;cursor:pointer}
.q.right{border-color:var(--ok);background:var(--ok-bg)} .q.wrong{border-color:var(--err);background:var(--err-bg)}
.explain{font-size:.9rem;margin-top:6px}
.pager{display:flex;justify-content:space-between;margin:20px 0}
.tutor{position:sticky;top:70px;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px;display:flex;flex-direction:column;gap:10px;max-height:calc(100vh - 90px)}
.tutor-head{display:flex;justify-content:space-between;align-items:baseline;gap:8px;flex-wrap:wrap}
.tutor-head h3{margin:0}
.chat{overflow-y:auto;flex:1;min-height:200px;display:flex;flex-direction:column;gap:10px;padding-right:4px}
.msg{padding:9px 12px;border-radius:10px;font-size:.93rem;overflow-wrap:anywhere}
.msg p{margin:.3em 0}.msg ol,.msg ul{padding-left:20px;margin:.3em 0}
.msg.user{background:var(--accent);color:#fff;align-self:flex-end;max-width:90%}
.msg.assistant{background:var(--surface2)}
.msg.assistant code{font-family:"JetBrains Mono",Consolas,monospace;background:var(--cmd-bg);color:var(--cmd-ink);padding:0 5px;border-radius:4px}
.msg .listen{margin-top:6px}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{border:1px solid var(--line);background:var(--surface2);color:var(--text);border-radius:999px;padding:4px 10px;font:inherit;font-size:.82rem;cursor:pointer}
.ask{display:flex;gap:8px}.ask textarea{flex:1;resize:vertical}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:18px}
ul.plain{list-style:none;padding:0}ul.plain li{padding:4px 0;border-bottom:1px solid var(--line)}
.prose{max-width:820px;margin:0 auto}
@media (max-width: 980px){
  .lesson-layout,.hero,.two-col{grid-template-columns:1fr}
  .tutor{position:static;max-height:none}
  .chat{max-height:60vh}
}
@media (max-width: 560px){
  .wrap{padding:16px 16px 40px}
  h1{font-size:1.5rem}
  .sec{padding:14px}
  .topbar{padding:10px 16px}
}