/* Hand-built figures for lesson 0, Math notation. */

/* shared: a plane with draggable handles */
.np { display: grid; gap: 22px; grid-template-columns: 1fr; align-items: center; }
@media (min-width: 760px) { .np { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); } }
.np-plane { width: 100%; max-width: 380px; margin: 0 auto; touch-action: none; }
.np-line { stroke: var(--line); }
.np-axis { stroke: var(--ink-3); stroke-width: 1.2; }
.np-vec { stroke-width: 3.5; stroke-linecap: round; }
.np-vec.va { stroke: var(--gold); }
.np-vec.vb { stroke: var(--accent); }
.np-lbl { font: italic 600 16px var(--f-body); }
.np-lbl.va { fill: var(--gold); } .np-lbl.vb { fill: var(--accent-ink); }
.np-handle { fill: var(--ink); fill-opacity: 0.12; stroke: var(--ink-2); stroke-width: 1.5; cursor: grab; }
.np-handle:focus-visible { outline: none; stroke: var(--gold); stroke-width: 3; }
.np-shadow { stroke: var(--accent); stroke-width: 6; stroke-opacity: 0.35; stroke-linecap: round; }
.np-drop { stroke: var(--ink-3); stroke-dasharray: 4 4; }
.np-side .kicker { margin-bottom: 10px; }
.np-work { font: 1rem/1.6 var(--f-mono); color: var(--ink-2); margin: 0 0 8px; }
.np-big { font: 400 2.4rem/1.1 var(--f-display); margin: 6px 0; }
.np-big.pos, .np-verdict.pos { color: var(--good); }
.np-big.neg, .np-verdict.neg { color: var(--bad); }
.np-big.zero, .np-verdict.zero { color: var(--gold); }
.np-verdict { font-weight: 600; margin: 0 0 6px; }

/* hero */
.hn-stack { display: grid; }
.hn { grid-area: 1 / 1; display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 12px 26px; min-height: 150px; opacity: 0; transition: opacity 0.35s; }
.hn.in { opacity: 1; }
.hn-sym { font-size: clamp(1.6rem, 4vw, 2.6rem); color: var(--ink); }
.hn-eq { font: 400 2rem var(--f-display); color: var(--ink-3); }
.hn-code { margin: 0; padding: 14px 18px; border-radius: var(--r-2); background: var(--surface); border: 1px solid var(--line-2); font: 0.95rem/1.55 var(--f-mono); color: var(--gold); text-align: left; }

/* 1: the grid */
.ng-ctl { display: flex; flex-wrap: wrap; gap: 10px 26px; margin-bottom: 14px; font-size: 0.85rem; }
.ng-name { font: 400 1.25rem var(--f-display); margin: 0 0 10px; }
.ng-grid { display: grid; gap: 4px; }
.ng-cell { aspect-ratio: 1; border-radius: 8px; border: 1px solid var(--line-2); background: var(--surface-2); font: 500 1rem var(--f-mono); color: var(--ink-2); cursor: pointer; }
.ng-cell.row, .ng-cell.col { background: var(--accent-soft); }
.ng-cell.on { background: var(--gold); color: var(--bg); border-color: var(--gold); }

/* 2: Σ and Π */
.sl { display: grid; gap: 28px; grid-template-columns: 1fr; }
@media (min-width: 900px) { .sl { grid-template-columns: 1.3fr 1fr; } }
.sl-formula { margin: 10px 0; overflow-x: auto; }
.sl-terms { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0; }
.sl-term { width: 34px; height: 34px; border-radius: 8px; display: grid; place-items: center; font: 500 0.9rem var(--f-mono); background: var(--surface-2); color: var(--ink-3); border: 1px solid var(--line); }
.sl-term.done { color: var(--ink); background: var(--accent-soft); }
.sl-term.now { box-shadow: 0 0 0 2px var(--gold); }
.sl-trace { min-height: 7.5em; margin: 8px 0; padding: 12px 14px; border-radius: var(--r-1); background: var(--bg-2); border: 1px solid var(--line); font: 0.82rem/1.6 var(--f-mono); color: var(--ink-2); overflow-x: auto; }
.sl-big { font: 400 1.9rem/1.1 var(--f-display); margin: 10px 0; }
.sl-big b { color: var(--gold); font-weight: 400; }
.sl-dots { display: flex; flex-wrap: wrap; gap: 4px; margin-bottom: 14px; }
.sl-dots i { width: 14px; height: 14px; border-radius: 50%; background: var(--good); opacity: calc(0.15 + var(--o) * 0.85); }
.sl-chain .slider { font-size: 0.85rem; margin: 6px 0; }

/* 4: length */
.vl-sq { stroke: none; }
.vl-sq.a { fill: var(--gold); fill-opacity: 0.18; }
.vl-sq.b { fill: var(--accent); fill-opacity: 0.18; }
.vl-legs { fill: none; stroke: var(--ink-3); stroke-dasharray: 5 4; }
.vl-circle { fill: none; stroke: var(--accent); stroke-dasharray: 3 4; }
.vl-unit { display: flex; gap: 8px; align-items: center; font-size: 0.85rem; color: var(--ink-2); margin-top: 12px; }

/* 5: matrix multiply */
.mm-row { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 18px; }
.mm-mat { display: flex; flex-direction: column; align-items: center; gap: 6px; }
.mm-name { font: italic 1.05rem var(--f-body); color: var(--ink-2); }
.mm-grid { display: grid; gap: 4px; padding: 6px; border-left: 2px solid var(--ink-3); border-right: 2px solid var(--ink-3); border-radius: 6px; }
.mm-cell { min-width: 44px; height: 40px; display: grid; place-items: center; border-radius: 6px; font: 500 1rem var(--f-mono); color: var(--ink-2); background: var(--surface-2); border: 1px solid transparent; }
button.mm-cell { cursor: pointer; border-color: var(--line-2); }
.mm-cell.hi-a { background: oklch(0.8 0.14 80 / 0.28); color: var(--ink); }
.mm-cell.hi-b { background: var(--accent-soft); color: var(--ink); }
.mm-cell.hi-ab { background: var(--gold); color: var(--bg); }
.mm-op { font: 400 1.6rem var(--f-display); color: var(--ink-3); }
.mm-work { font: 0.98rem/1.5 var(--f-mono); color: var(--ink-2); margin: 14px 0 4px; }
.mm-shapes { margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--line); font-size: 0.9rem; }
.mm-shapes select { font: inherit; color: var(--ink); background: var(--surface-2); border: 1px solid var(--line-2); border-radius: 6px; padding: 2px 6px; }
.mm-verdict { margin: 10px 0 0; color: var(--ink-2); }

/* 6: e and log */
.lu { display: grid; gap: 26px; grid-template-columns: 1fr; }
@media (min-width: 860px) { .lu { grid-template-columns: 1fr 1fr; } }
.lu .slider { font-size: 0.85rem; margin: 6px 0; }
.lu-rows { margin-top: 12px; display: grid; gap: 8px; font-size: 0.9rem; }
.lu-row { display: flex; justify-content: space-between; gap: 12px; padding: 10px 12px; border-radius: var(--r-1); background: var(--surface-2); border: 1px solid var(--line); }
.lu-row b { font-family: var(--f-mono); }
.lu-row.bad { border-color: var(--bad); } .lu-row.bad b { color: var(--bad); }
.lu-row.good b { color: var(--good); }
.lu-pen { height: 16px; border-radius: 8px; background: var(--surface-2); overflow: hidden; margin: 14px 0 8px; }
.lu-pen i { display: block; height: 100%; background: linear-gradient(90deg, var(--good), var(--gold), var(--bad)); transition: width 0.2s; }
.lu-pen-read { font-size: 0.95rem; }

/* 7: softmax */
.sb { display: grid; gap: 22px; grid-template-columns: 1fr; }
@media (min-width: 860px) { .sb { grid-template-columns: 1fr 1.2fr; align-items: center; } }
.sb-in .slider { font-size: 0.85rem; margin: 6px 0; }
.sb-row { display: grid; grid-template-columns: 110px 1fr 48px; gap: 10px; align-items: center; margin: 10px 0; font-family: var(--f-ui); font-size: 0.88rem; }
.sb-bar { height: 22px; border-radius: 6px; background: var(--surface-2); overflow: hidden; }
.sb-bar i { display: block; height: 100%; background: var(--accent); transition: width 0.2s; }
.sb-row.win .sb-bar i { background: var(--gold); }
.sb-row b { text-align: right; font-variant-numeric: tabular-nums; }

/* 8: spread */
.sd-scroll { overflow-x: auto; }
.sd-line { width: 100%; min-width: 540px; height: auto; touch-action: none; }
.sd-band { fill: var(--accent-soft); }
.sd-mean { stroke: var(--ink-2); stroke-dasharray: 5 4; }
.sd-dot { fill: var(--gold); stroke: var(--bg-2); stroke-width: 2; cursor: grab; }
.sd-dot:focus-visible { outline: none; stroke: var(--ink); stroke-width: 3; }
.sd-dist { stroke: var(--ink-3); stroke-width: 1.5; }
.sd-bar { fill: var(--bad); fill-opacity: 0.55; }
.sd-var { stroke: var(--gold); stroke-width: 2; stroke-dasharray: 6 4; }
.sd-tick { font: 12px var(--f-mono); fill: var(--ink-3); }
.sd-tick.mu { fill: var(--ink); font-weight: 600; }
.sd-read { display: flex; flex-wrap: wrap; gap: 8px 22px; font-size: 0.95rem; margin: 6px 0; }
.sd-read b { font: 400 1.5rem var(--f-display); }

/* 9: slopes */
.gs { display: grid; gap: 26px; grid-template-columns: 1fr; }
@media (min-width: 900px) { .gs { grid-template-columns: 1fr 1fr; } }
.gs-curve { width: 100%; max-width: 380px; height: auto; }
.gs-f { fill: none; stroke: var(--accent); stroke-width: 2.5; }
.gs-tan { stroke: var(--gold); stroke-width: 2; }
.gs-pt { fill: var(--gold); }
.gs-dot { fill: var(--ink-3); }
.gs-ring { fill: none; stroke: var(--line-2); }
.gs-path { fill: none; stroke: var(--ink-3); stroke-dasharray: 3 3; }
.gs-arrow { stroke: var(--good); stroke-width: 3; stroke-linecap: round; }
.gs-bowl { cursor: crosshair; }
.gs-read, .gs-bowl-read { font-size: 0.88rem; color: var(--ink-2); }
.gs .slider { font-size: 0.85rem; }

/* 10: given */
.gg { display: grid; gap: 22px; grid-template-columns: 1fr; align-items: center; }
@media (min-width: 760px) { .gg { grid-template-columns: minmax(0, 300px) 1fr; } }
.gg-grid { display: grid; grid-template-columns: repeat(10, 1fr); gap: 4px; }
.gg-grid i { aspect-ratio: 1; border-radius: 4px; background: var(--surface-2); border: 2px solid transparent; transition: opacity 0.3s; }
.gg-grid i.spam { background: var(--bad); }
.gg-grid i.free { border-color: var(--gold); }
.gg-grid i.out { opacity: 0.12; }
.gg-big { font: 400 1.6rem/1.2 var(--f-display); margin: 16px 0 10px; }
.gg-big b { color: var(--gold); font-weight: 400; }
.gg-key { display: inline-block; width: 12px; height: 12px; border-radius: 3px; vertical-align: -1px; }
.gg-key.spam { background: var(--bad); } .gg-key.free { border: 2px solid var(--gold); }

/* 11: Big-O */
.bo-row { display: grid; grid-template-columns: 96px 1fr 130px 60px; gap: 10px; align-items: center; margin: 10px 0; font-size: 0.86rem; }
.bo-bar { height: 20px; border-radius: 6px; background: var(--surface-2); overflow: hidden; }
.bo-bar i { display: block; height: 100%; background: var(--accent); transition: width 0.3s; }
.bo-v { text-align: right; color: var(--ink-3); font-size: 0.8rem; }
.bo-m { color: var(--gold); font-variant-numeric: tabular-nums; }
.bo-n { font-size: 0.9rem; color: var(--ink-2); }
@media (max-width: 560px) { .bo-row { grid-template-columns: 78px 1fr 44px; } .bo-v { display: none; } }

/* 12: Greek letters */
.gc-mode { margin-bottom: 14px; }
.gc { display: grid; gap: 8px; grid-template-columns: repeat(auto-fill, minmax(118px, 1fr)); }
.gc-card { min-height: 112px; border-radius: var(--r-2); border: 1px solid var(--line-2); background: var(--surface-2); cursor: pointer; padding: 10px; display: grid; place-items: center; text-align: center; color: var(--ink); }
.gc-l { font: 400 2.4rem var(--f-body); }
.gc-back { display: none; font: 600 0.9rem var(--f-ui); }
.gc-back small { display: block; font-weight: 400; font-size: 0.74rem; color: var(--ink-2); margin-top: 4px; line-height: 1.35; }
.gc-card.flipped .gc-l { display: none; }
.gc-card.flipped .gc-back { display: block; }
.gc-card.right { border-color: var(--good); background: color-mix(in oklab, var(--good) 16%, transparent); }
.gc-card.wrong { border-color: var(--bad); }