:root {
  --bg: #0b1220;
  --panel: #111a2e;
  --panel2: #16223b;
  --line: #243350;
  --text: #dbe6ff;
  --dim: #8fa3c7;
  --green: #39ff9c;
  --amber: #ffc857;
  --red: #ff6b7a;
  --blue: #6cb8ff;
  --violet: #b69cff;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text); font: 16px/1.5 var(--sans);
  background-image: radial-gradient(circle at 20% -10%, #16305a55, transparent 45%), radial-gradient(circle at 100% 0, #3a1f6a33, transparent 40%);
  min-height: 100vh; display: flex; flex-direction: column;
}
a { color: var(--blue); }
h1, h2, h3 { line-height: 1.2; margin: 0 0 .5em; }
h1 { font-size: 1.7rem; } h2 { font-size: 1.25rem; } h3 { font-size: 1.05rem; }
code, .mono, pre { font-family: var(--mono); }
:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }

/* header */
.top { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 20px; padding: 12px 16px; border-bottom: 1px solid var(--line); background: #0b1220e6; position: sticky; top: 0; z-index: 5; backdrop-filter: blur(6px); }
.brand { font: 700 1.2rem var(--mono); color: var(--text); text-decoration: none; display: flex; align-items: center; gap: 8px; }
.chip { background: var(--green); color: #04130b; padding: 1px 8px; border-radius: 6px; }
.hud { display: flex; align-items: center; gap: 12px; margin-left: auto; font: 600 .85rem var(--mono); color: var(--dim); }
.hud b { color: var(--text); }
.xpbar { width: 110px; height: 8px; background: var(--panel2); border-radius: 8px; overflow: hidden; border: 1px solid var(--line); }
.xpbar i { display: block; height: 100%; background: linear-gradient(90deg, var(--green), var(--blue)); transition: width .4s; }
.nav { display: flex; gap: 4px; width: 100%; }
.nav a { color: var(--dim); text-decoration: none; padding: 6px 12px; border-radius: 8px; font-weight: 600; font-size: .95rem; }
.nav a:hover { color: var(--text); background: var(--panel); }
.nav a.on { color: #04130b; background: var(--green); }
@media (min-width: 760px) { .nav { width: auto; } .hud { margin-left: 0; } .top { flex-wrap: nowrap; } .nav { margin-left: auto; } }

main { flex: 1; width: 100%; max-width: 1000px; margin: 0 auto; padding: 20px 16px 40px; outline: none; }
.foot { text-align: center; color: var(--dim); font-size: .8rem; padding: 18px 16px; border-top: 1px solid var(--line); }

/* cards & grids */
.grid { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); }
.tile { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 14px; text-align: left; color: var(--text); cursor: pointer; font: inherit; display: flex; flex-direction: column; gap: 6px; text-decoration: none; transition: transform .12s, border-color .12s; }
.tile:hover { transform: translateY(-2px); border-color: var(--green); }
.tile .ico { font-size: 1.6rem; }
.tile .nm { font-weight: 700; }
.tile .sub { color: var(--dim); font-size: .85rem; }
.tile .meta { margin-top: auto; font: .78rem var(--mono); color: var(--dim); display: flex; justify-content: space-between; gap: 8px; }
.bar { height: 6px; background: var(--panel2); border-radius: 6px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--green); }
.sec { margin: 26px 0 10px; display: flex; align-items: baseline; gap: 10px; }
.sec h2 { margin: 0; } .sec small { color: var(--dim); }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 16px; }
.hero { display: grid; gap: 14px; grid-template-columns: 1fr; }
@media (min-width: 760px) { .hero { grid-template-columns: 1.4fr 1fr; } }
.lede { color: var(--dim); margin: 0 0 12px; }

/* buttons */
.btn { font: 600 .95rem var(--sans); border: 1px solid var(--line); background: var(--panel2); color: var(--text); padding: 9px 16px; border-radius: 10px; cursor: pointer; text-decoration: none; display: inline-block; }
.btn:hover { border-color: var(--blue); }
.btn.go { background: var(--green); color: #04130b; border-color: var(--green); }
.btn.bad { background: #3a1820; border-color: var(--red); }
.btn.ghost { background: transparent; }
.btn:disabled { opacity: .5; cursor: default; }
.row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

/* code */
pre.code { margin: 10px 0; padding: 12px 14px; background: #070c17; border: 1px solid var(--line); border-radius: 10px; overflow-x: auto; font-size: .95rem; line-height: 1.6; white-space: pre; }
pre.code mark { background: #ffc85733; color: var(--amber); padding: 0 2px; border-radius: 3px; outline: 1px dashed var(--amber); }
.kw { color: var(--violet); } .num { color: var(--amber); } .cm { color: #6e82a8; }
table.regs { border-collapse: collapse; font: .9rem var(--mono); margin: 8px 0; }
table.regs td { padding: 2px 14px 2px 0; } table.regs td:first-child { color: var(--dim); }
.mem { font: .88rem var(--mono); color: var(--dim); }
.mem b { color: var(--text); }

/* game */
.gamehead { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: center; margin-bottom: 14px; }
.gamehead h1 { margin: 0; font-size: 1.3rem; }
.progress { flex: 1; min-width: 140px; }
.stat { font: 600 .85rem var(--mono); color: var(--dim); } .stat b { color: var(--text); }
.q { font-size: 1.1rem; margin: 0 0 8px; }
.opts { display: grid; gap: 8px; margin: 12px 0; }
.opt { text-align: left; font: inherit; background: var(--panel2); color: var(--text); border: 1px solid var(--line); border-radius: 10px; padding: 11px 14px; cursor: pointer; }
.opt:hover:not(:disabled) { border-color: var(--blue); }
.opt.right { border-color: var(--green); background: #0f3a2a; }
.opt.wrong { border-color: var(--red); background: #3a1820; }
.opt.pick { border-color: var(--amber); background: #3a3010; }
.opt:disabled { cursor: default; }
.opt .k { font: .75rem var(--mono); color: var(--dim); margin-right: 8px; }
.fields { display: grid; gap: 10px; margin: 12px 0; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); }
.fields label { display: grid; gap: 4px; font-size: .85rem; color: var(--dim); }
.fields input { font: 1rem var(--mono); background: #070c17; color: var(--text); border: 1px solid var(--line); border-radius: 8px; padding: 9px 10px; width: 100%; }
.fields input.right { border-color: var(--green); } .fields input.wrong { border-color: var(--red); }
.flags { display: flex; gap: 8px; flex-wrap: wrap; margin: 12px 0; }
.flag { font: 700 1.1rem var(--mono); min-width: 64px; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--line); background: var(--panel2); color: var(--dim); cursor: pointer; }
.flag.on { background: #0f3a2a; border-color: var(--green); color: var(--green); }
.flag.right { outline: 2px solid var(--green); } .flag.wrong { outline: 2px solid var(--red); }
.fb { margin-top: 12px; padding: 12px 14px; border-radius: 10px; border: 1px solid var(--line); background: var(--panel2); }
.fb.ok { border-color: var(--green); } .fb.no { border-color: var(--red); }
.fb h3 { margin-bottom: 4px; } .fb.ok h3 { color: var(--green); } .fb.no h3 { color: var(--red); }
.hearts { letter-spacing: 3px; }
.timer { height: 5px; background: var(--panel2); border-radius: 5px; overflow: hidden; margin-bottom: 10px; }
.timer i { display: block; height: 100%; background: var(--amber); transform-origin: left; }

/* flashcard */
.fc { perspective: 1000px; margin: 14px 0; }
.fcard { min-height: 220px; border-radius: 16px; border: 1px solid var(--line); background: linear-gradient(160deg, var(--panel2), var(--panel)); padding: 22px; display: flex; flex-direction: column; justify-content: center; cursor: pointer; text-align: center; font-size: 1.2rem; width: 100%; color: var(--text); font-family: inherit; }
.fcard.back { border-color: var(--green); }
.fcard .tag { font: .75rem var(--mono); color: var(--dim); margin-bottom: 10px; }
.fcard .hint { font-size: .8rem; color: var(--dim); margin-top: 14px; }

/* sorter */
.sort { display: grid; gap: 14px; grid-template-columns: 1fr; }
@media (min-width: 760px) { .sort { grid-template-columns: 1fr 1fr; } }
.col { background: #070c17; border: 1px dashed var(--line); border-radius: 12px; padding: 10px; min-height: 120px; }
.col h3 { font-size: .85rem; color: var(--dim); margin: 0 0 8px; font-weight: 600; }
.line { display: block; width: 100%; text-align: left; font: .9rem var(--mono); white-space: pre; background: var(--panel2); border: 1px solid var(--line); color: var(--text); border-radius: 8px; padding: 6px 10px; margin-bottom: 6px; cursor: pointer; overflow-x: auto; }
.line:hover { border-color: var(--blue); }
.line.right { border-color: var(--green); } .line.wrong { border-color: var(--red); }
.line .cm { margin-left: 12px; }
.line .n { color: var(--dim); margin-right: 8px; }

/* badges, tables */
.badges { display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); }
.badge { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 10px 12px; display: flex; gap: 10px; align-items: center; }
.badge.off { opacity: .4; filter: grayscale(1); }
.badge .ico { font-size: 1.5rem; } .badge small { display: block; color: var(--dim); font-size: .78rem; }
.statgrid { display: grid; gap: 10px; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); }
.statgrid .panel { text-align: center; } .statgrid b { display: block; font: 700 1.5rem var(--mono); color: var(--green); }
.pill { font: .72rem var(--mono); padding: 1px 7px; border: 1px solid var(--line); border-radius: 20px; color: var(--dim); }

/* toasts */
#toasts { position: fixed; right: 14px; bottom: 14px; display: grid; gap: 8px; z-index: 20; pointer-events: none; }
.toast { background: #0f3a2a; border: 1px solid var(--green); color: var(--text); padding: 8px 14px; border-radius: 10px; font-weight: 600; animation: pop .25s ease-out; box-shadow: 0 6px 20px #0008; }
.toast.badge-t { background: #3a3010; border-color: var(--amber); }
@keyframes pop { from { transform: translateY(10px) scale(.95); opacity: 0; } to { transform: none; opacity: 1; } }
@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }

/* sandbox */
.ln.last { background: #0f3a2a55; }
.sbstatus { margin-top: 8px; font: .85rem var(--mono); white-space: pre-wrap; color: var(--dim); min-height: 1.5em; }
.sbstatus.bad { color: var(--red); } .sbstatus.ok { color: var(--green); }
.flagrow { display: flex; gap: 8px; margin-bottom: 8px; }
.fl { font: 600 .9rem var(--mono); padding: 4px 10px; border: 1px solid var(--line); border-radius: 8px; color: var(--dim); }
.fl b { margin-left: 6px; color: var(--text); } .fl.on { border-color: var(--green); } .fl.on b { color: var(--green); }
.chg { color: var(--amber) !important; } .fl.chg { border-color: var(--amber); }
table.regs td.dim, .dim { color: var(--dim); }
.addr { font: .9rem var(--mono); background: #070c17; color: var(--text); border: 1px solid var(--line); border-radius: 8px; padding: 6px 8px; width: 90px; }
#mem { overflow-x: auto; white-space: pre; font-size: .78rem; }
select.btn { max-width: 100%; }

/* read code */
details.rl { border-bottom: 1px solid #16223b; }
details.rl summary { cursor: pointer; list-style: none; padding: 1px 0; }
details.rl summary::-webkit-details-marker { display: none; }
details.rl summary:hover { background: var(--panel2); }
details.rl[open] summary { background: var(--panel2); }
details.rl .rx { padding: 6px 14px 10px 32px; font: .92rem/1.5 var(--sans); white-space: normal; background: #0d1527; }
details.rl .rx p { margin: .3em 0; } details.rl .rx ul { margin: .3em 0; padding-left: 1.2em; color: var(--dim); }
.rx code, #rdout code { font: .85rem var(--mono); background: #070c17; padding: 0 4px; border-radius: 4px; color: var(--amber); }
#rdout ul { color: var(--dim); padding-left: 1.2em; }

/* guides */
.guide { max-width: 760px; }
.guide h2 { margin-top: 1.6em; font-size: 1.25rem; border-bottom: 1px solid var(--line); padding-bottom: 4px; }
.guide h3 { margin-top: 1.2em; }
.guide p, .guide li { color: var(--text); }
.guide code { font: .88rem var(--mono); background: #070c17; padding: 1px 5px; border-radius: 4px; color: var(--amber); }
.guide pre.code { white-space: pre; }
.guide ul, .guide ol { padding-left: 1.3em; }
.callout { background: #16223b; border-left: 3px solid var(--blue); border-radius: 6px; padding: 8px 14px; margin: 12px 0; color: var(--text); }
.tablewrap { overflow-x: auto; margin: 10px 0; }
table.gt { border-collapse: collapse; font-size: .9rem; min-width: 100%; }
table.gt th, table.gt td { border: 1px solid var(--line); padding: 5px 9px; text-align: left; vertical-align: top; }
table.gt th { background: var(--panel2); } table.gt td code { white-space: nowrap; }
.gloss dt { font-weight: 700; margin-top: 12px; } .gloss dd { margin: 2px 0 0 0; color: var(--dim); }
.codebtn { margin-left: auto; border: 1px solid var(--line); } .codebtn:hover { border-color: var(--green); color: var(--green) !important; }

/* sandbox v2 */
.toolbar { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin-bottom: 10px; }
.toolbar .sep { width: 1px; height: 22px; background: var(--line); margin: 0 4px; }
.sbgrid { display: grid; gap: 14px; grid-template-columns: minmax(0, 1fr); }
@media (min-width: 980px) { .sbgrid { grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr); } }
.col-main, .col-side { min-width: 0; }
.edwrap { display: flex; border: 1px solid var(--line); border-radius: 10px; background: #070c17; overflow: hidden; }
.gutter { margin: 0; padding: 10px 8px 10px 10px; text-align: right; color: var(--dim); font: .88rem/1.5 var(--mono); overflow: hidden; user-select: none; min-width: 3.2em; border-right: 1px solid var(--line); height: 460px; }
.edwrap textarea { flex: 1; min-width: 0; height: 460px; resize: vertical; border: 0; outline: 0; background: transparent; color: var(--text); font: .88rem/1.5 var(--mono); padding: 10px 12px; white-space: pre; overflow: auto; tab-size: 8; }
.listing { height: 460px; overflow: auto; background: #070c17; border: 1px solid var(--line); border-radius: 10px; font: .85rem/1.5 var(--mono); }
.listing .lhead { position: sticky; top: 0; background: #070c17; padding: 4px 6px; border-bottom: 1px solid var(--line); z-index: 1; display: flex; align-items: center; }
.ln { display: flex; gap: 10px; padding: 0 10px 0 4px; white-space: pre; min-width: max-content; }
.ln .ad { color: var(--dim); min-width: 5.2em; } .ln .mc { color: #7fa6d9; min-width: 11em; } .ln .lno { color: #556a8f; min-width: 2.6em; text-align: right; }
.bp { width: 14px; height: 14px; margin: 4px 0; border-radius: 50%; border: 1px solid #556a8f; background: transparent; cursor: pointer; padding: 0; align-self: center; flex: none; }
.bp:disabled { visibility: hidden; } .bp.on { background: var(--red); border-color: var(--red); }
.problems { margin-top: 8px; display: grid; gap: 4px; }
.perr { text-align: left; font: .85rem var(--mono); color: var(--red); background: #2a1219; border: 1px solid #5a2430; border-radius: 6px; padding: 5px 9px; cursor: pointer; overflow-wrap: anywhere; }
.con-panel { margin-top: 10px; }
.out { margin: 6px 0; height: 150px; overflow: auto; background: #070c17; border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; font: .88rem/1.4 var(--mono); white-space: pre-wrap; overflow-wrap: anywhere; }
.inrow { display: flex; gap: 6px; }
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--line); }
.tab { background: transparent; border: 0; color: var(--dim); padding: 6px 12px; cursor: pointer; font: 600 .9rem var(--sans); border-bottom: 2px solid transparent; }
.tab.on { color: var(--text); border-bottom-color: var(--green); }
.linkbtn { background: none; border: 0; color: var(--blue); cursor: pointer; font: inherit; padding: 0; text-decoration: underline; }
tr.cur td { background: #3a3010; }
.sbstatus { overflow-wrap: anywhere; }

.reflist { margin: 0; padding-left: 1.1em; display: grid; gap: 10px; } .reflist a { overflow-wrap: anywhere; }

.pill.v-CONFIRMED { color: var(--green); border-color: var(--green); } .pill.v-CORRECTED { color: var(--amber); border-color: var(--amber); } .pill.v-UNVERIFIED { color: var(--red); border-color: var(--red); }
details.rl summary .pill { margin: 3px 8px 3px 4px; align-self: center; }

/* keep the page from scrolling sideways: wide content scrolls inside its own box */
html { overflow-x: hidden; }
body { max-width: 100%; }
main, .panel, .grid > *, .hero > *, .sbgrid > *, .col-main, .col-side, .guide { min-width: 0; max-width: 100%; }
pre, pre.code, .tablewrap, .listing, .out, #mem, .mem { max-width: 100%; overflow-x: auto; }
.guide p, .guide li, .lede, .stat, dd, .tile .sub { overflow-wrap: anywhere; }
table.gt, table.regs { max-width: 100%; }
img, svg, video { max-width: 100%; }

/* fixes: the hidden attribute must win over component display rules; fixed-height editor with matching gutter */
[hidden] { display: none !important; }
main { max-width: 1180px; }
.edwrap { height: 460px; }
.edwrap .gutter { height: 100%; }
.edwrap textarea { height: 100%; resize: none; }
#src { width: auto; }
.listing { overflow: auto; }
@media (max-width: 700px) { .edwrap, .listing { height: 380px; } .out { height: 120px; } }

/* homework */
.hwcode { width: 100%; height: 260px; background: #070c17; color: var(--text); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; font: .88rem/1.5 var(--mono); white-space: pre; overflow: auto; resize: vertical; tab-size: 8; }
details.wk > summary { cursor: pointer; list-style: none; display: inline-block; } details.wk > summary::-webkit-details-marker { display: none; }
details.wk[open] > summary { margin-bottom: 4px; }

.projbar { margin-bottom: 2px; }
#proj { min-width: 160px; max-width: 100%; }