/* ══════════════════════════════════════════════════════════
   overview.html  ·  page-specific styles
   ══════════════════════════════════════════════════════════ */

:root {
    --bg: #0a0a10;
    --bg-2: #12131c;
    --bg-panel: rgba(22, 23, 32, 0.75);
    --fg: #eef0f5;
    --text: #eef0f5;
    --text-dim: #d4d7e0;
    --muted: #8b90a3;
    --border: rgba(255, 255, 255, 0.09);
    --border-hover: rgba(255, 255, 255, 0.18);

    /* page semantic palette */
    --c-input:    #58a6ff;   /* analog input trace */
    --c-output:   #ffcf5c;   /* digital output / pulse trace */
    --c-output2:  #7be089;   /* secondary output / load */
    --c-thresh:   #ff5c7a;   /* threshold / setpoint */
    --c-low:      #8b90a3;   /* off / inactive shading */
    --c-high:     #7be089;   /* on / active shading */
    --c-hot:      #f97066;   /* warning / hot region */

    --accent: var(--site-accent);
    --accent-soft: var(--site-accent-soft);
    --accent-soft-faint: var(--site-accent-soft-faint);
    --accent-soft-edge: var(--site-accent-soft-edge);

    --grid-line: rgba(255, 255, 255, 0.06);
    --grid-zero: rgba(255, 255, 255, 0.30);
    --tick-line: rgba(255, 255, 255, 0.25);
    --slider-track: rgba(255, 255, 255, 0.12);
    --pill-bg: rgba(255, 255, 255, 0.03);

    --body-size: 17px;
    --math-size: 18px;
    --hero-size: 60px;
}

[data-theme="light"] {
    --bg: #f5f5f7;
    --bg-2: #ffffff;
    --bg-panel: rgba(255, 255, 255, 0.92);
    --fg: #1a1a1e;
    --text: #1a1a1e;
    --text-dim: #2b2d38;
    --muted: #6a6f7c;
    --border: rgba(0, 0, 0, 0.10);
    --border-hover: rgba(0, 0, 0, 0.22);

    --c-input:    #1d4ed8;
    --c-output:   #b88200;
    --c-output2:  #2f8f3f;
    --c-thresh:   #dc2626;
    --c-low:      #6a6f7c;
    --c-high:     #2f8f3f;
    --c-hot:      #c0382b;

    --grid-line: rgba(0, 0, 0, 0.07);
    --grid-zero: rgba(0, 0, 0, 0.32);
    --tick-line: rgba(0, 0, 0, 0.22);
    --slider-track: rgba(0, 0, 0, 0.12);
    --pill-bg: rgba(0, 0, 0, 0.03);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
    background: var(--bg);
    color: var(--fg);
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    font-size: var(--body-size);
    line-height: 1.55;
    -webkit-font-smoothing: antialiased;
}
body { overflow-x: hidden; min-height: 100vh; }

.katex { font-size: var(--math-size) !important; }
.katex-display { margin: 0.6em 0 !important; }
.katex-display > .katex { font-size: calc(var(--math-size) * 1.06) !important; }
h1 .katex, h2 .katex, h3 .katex { font-size: inherit !important; }

a { color: var(--accent); }

/* ─── Brand and back ─── */
.brand {
    position: fixed; top: 20px; left: 24px; z-index: 40;
    font-size: 12px; color: var(--muted);
    letter-spacing: 0.08em; text-transform: uppercase;
    font-family: 'JetBrains Mono', monospace;
    display: flex; align-items: center; gap: 10px;
}
.brand .mark {
    width: 10px; height: 10px; border-radius: 50%;
    background: conic-gradient(var(--c-input), var(--c-output), var(--c-thresh), var(--c-output2), var(--c-input));
}

.back-btn {
    position: fixed; top: 14px; right: 56px; z-index: 9999;
    display: inline-flex; align-items: center; gap: 8px;
    padding: 7px 14px; border-radius: 999px;
    background: var(--bg-panel); border: 1px solid var(--border);
    color: var(--fg); text-decoration: none;
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px; letter-spacing: 0.06em; text-transform: uppercase;
    backdrop-filter: blur(8px); transition: all 0.15s;
}
.back-btn:hover { border-color: var(--accent); color: var(--accent); }

/* ─── Landing hero ─── */
.landing {
    min-height: 100vh; display: grid; place-items: center;
    padding: 120px 56px 80px; text-align: center; position: relative;
}
.landing .meta {
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px; color: var(--muted);
    letter-spacing: 0.2em; text-transform: uppercase;
    margin-bottom: 28px;
}
h1.hero {
    font-size: var(--hero-size); line-height: 1.02;
    font-weight: 600; letter-spacing: -0.025em;
    margin: 0 auto 24px; max-width: 22ch;
}
h1.hero em {
    font-style: normal;
    background: linear-gradient(135deg, var(--c-input), var(--c-output));
    -webkit-background-clip: text; background-clip: text; color: transparent;
}
.landing .sub {
    color: var(--muted); font-size: 18px;
    max-width: 64ch; margin: 12px auto 0; line-height: 1.6;
}
.landing .tags {
    margin-top: 36px; display: flex; gap: 12px;
    justify-content: center; flex-wrap: wrap;
}
.field-tag {
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px; color: var(--muted);
    letter-spacing: 0.12em; text-transform: uppercase;
    display: inline-block; padding: 4px 10px;
    border: 1px solid var(--border); border-radius: 4px;
}
.scroll-hint {
    position: absolute; bottom: 32px; left: 50%; transform: translateX(-50%);
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px; letter-spacing: 0.2em;
    color: var(--muted); text-transform: uppercase;
    display: flex; flex-direction: column; align-items: center; gap: 8px;
}
.scroll-hint .line {
    width: 1px; height: 32px;
    background: linear-gradient(var(--muted), transparent);
    animation: pulse 2s infinite;
}
@keyframes pulse {
    0%, 100% { opacity: 0.3; } 50% { opacity: 1; }
}

/* ─── Section divider ─── */
.section-divider {
    padding: 40px 56px 0;
    max-width: 1200px;
    margin: 0 auto;
}
.section-divider .lab {
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px; color: var(--accent);
    letter-spacing: 0.22em; text-transform: uppercase;
    display: flex; align-items: center; gap: 12px;
}
.section-divider .lab .bar {
    flex: 1; height: 1px; background: var(--border);
}

/* ─── Scene layout ─── */
section.scene {
    min-height: 100vh; padding: 80px 40px 80px;
    display: grid;
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.5fr);
    gap: 28px; align-items: start;
    border-bottom: 1px solid var(--border);
    max-width: 1400px; margin: 0 auto;
}
section.scene .copy { max-width: 560px; }

.eyebrow {
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px; letter-spacing: 0.18em; text-transform: uppercase;
    color: var(--muted); margin-bottom: 18px;
    display: flex; align-items: center; gap: 10px;
}
.eyebrow .num { color: var(--accent); }
.eyebrow .bar { flex: 0 0 28px; height: 1px; background: var(--accent); }

h2 {
    font-size: 34px; line-height: 1.12;
    font-weight: 600; letter-spacing: -0.02em;
    margin: 0 0 18px; color: var(--fg);
}
h2 em { font-style: normal; }
h2 em.input  { color: var(--c-input); }
h2 em.output { color: var(--c-output); }
h2 em.thresh { color: var(--c-thresh); }
h2 em.high   { color: var(--c-high); }

h3 {
    font-size: 17px; font-weight: 600;
    margin: 22px 0 8px; color: var(--fg); letter-spacing: -0.01em;
}

p { margin: 0 0 14px; color: var(--text-dim); }
p.lead { font-size: calc(var(--body-size) + 1px); color: var(--fg); }
p.dim  { color: var(--muted); }

ul.bullets { margin: 0 0 14px; padding-left: 18px; color: var(--text-dim); }
ul.bullets li { margin-bottom: 6px; }

strong { color: var(--fg); font-weight: 600; }

.callout {
    margin-top: 18px; padding: 14px 18px;
    border-left: 2px solid var(--accent);
    background: var(--accent-soft-faint);
    border-radius: 0 8px 8px 0;
    font-size: 14px; color: var(--text-dim); line-height: 1.7;
}

/* ─── Plot panel ─── */
.plot-stack {
    display: flex; flex-direction: column; gap: 14px;
    width: 100%; max-width: 760px;
}
.plot-box {
    position: relative;
    border: 1px solid var(--border);
    border-radius: 12px; background: var(--bg-2);
    overflow: hidden; width: 100%;
}
.plot-box.scene-box { aspect-ratio: 1.55 / 1; }
.plot-box.trace-box { aspect-ratio: 2.2 / 1; }
.plot-box.circuit-box { aspect-ratio: 3.2 / 1; }
#sec-debounce .plot-box.trace-box { aspect-ratio: 1.7 / 1; }
.plot-box.freq-box  { aspect-ratio: 2.4 / 1; }
.plot-box.bulb-box  { aspect-ratio: 1 / 1; flex: 0 0 200px; }
.plot-box svg { display: block; width: 100%; height: 100%; }

.pwm-bottom {
    display: flex; gap: 14px; align-items: stretch;
}
.pwm-bottom .readout.pwm-readout-col {
    flex: 1; flex-direction: column; gap: 10px;
    align-content: flex-start;
}
.pwm-bottom .readout.pwm-readout-col .item { min-width: 0; }
@media (max-width: 700px) {
    .pwm-bottom { flex-direction: column; }
    .plot-box.bulb-box { flex: 0 0 auto; max-width: 220px; align-self: center; }
}

/* ─── Keyboard / debounce demo ─── */
.kbd-io {
    display: flex; flex-direction: column;
    gap: 8px;
}
.kbd-io-card {
    position: relative;
    border: 1px solid var(--border);
    border-radius: 14px;
    background:
        linear-gradient(180deg,
            color-mix(in srgb, var(--bg-2) 96%, var(--fg) 4%) 0%,
            var(--bg-2) 100%);
    box-shadow:
        inset 0 1px 0 rgba(255, 255, 255, 0.03),
        0 2px 10px rgba(0, 0, 0, 0.18);
    overflow: hidden;
    transition: border-color 0.18s ease, box-shadow 0.18s ease;
}
[data-theme="light"] .kbd-io-card {
    box-shadow:
        inset 0 1px 0 rgba(255, 255, 255, 0.7),
        0 1px 3px rgba(0, 0, 0, 0.06);
}
.kbd-io-card::before {
    content: "";
    position: absolute; left: 16px; top: 0;
    width: 36px; height: 2px;
    background: linear-gradient(90deg, var(--c-input), transparent);
    border-radius: 0 0 2px 2px;
    opacity: 0.7;
}
.kbd-io-card:focus-within {
    border-color: var(--c-input);
    box-shadow:
        inset 0 1px 0 rgba(255, 255, 255, 0.04),
        0 0 0 3px color-mix(in srgb, var(--c-input) 18%, transparent),
        0 4px 18px rgba(0, 0, 0, 0.25);
}
.kbd-io-card:focus-within::before {
    opacity: 1;
    background: linear-gradient(90deg, var(--c-input), color-mix(in srgb, var(--c-input) 30%, transparent));
}

.kbd-io-head {
    display: flex; align-items: center; justify-content: space-between;
    padding: 12px 18px 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--muted);
}
.kbd-io-head .kbd-io-label {
    color: var(--c-input);
    font-weight: 600;
}
.kbd-io-head .kbd-io-meta {
    color: var(--muted);
    font-size: 9.5px;
    opacity: 0.75;
}

.kbd-input {
    display: block;
    width: 100%;
    border: none;
    background: transparent;
    color: var(--fg);
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 17px;
    line-height: 1.55;
    padding: 10px 18px 16px;
    resize: none;
    outline: none;
    min-height: 70px;
    caret-color: var(--c-input);
    word-break: break-all;
    white-space: pre-wrap;
}
.kbd-input::placeholder {
    color: var(--muted);
    font-style: italic;
    opacity: 0.7;
}

.kbd-io-output {
    padding: 4px 18px 0;
    display: flex; align-items: baseline; gap: 10px;
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 15px;
    line-height: 1.55;
    word-break: break-all;
    white-space: pre-wrap;
    min-height: 28px;
}
.kbd-io-output-label {
    flex: 0 0 auto;
    color: var(--muted);
    font-size: 9.5px;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    font-weight: 600;
    align-self: center;
}
.kbd-io-output-arrow {
    flex: 0 0 auto;
    color: var(--c-output);
    font-size: 14px;
    align-self: center;
    opacity: 0.75;
}
.kbd-io-output-text {
    flex: 1; min-width: 0;
    color: var(--c-output);
}
.kbd-io-output-text:empty::before {
    content: "output will appear here…";
    color: var(--muted);
    font-style: italic;
    opacity: 0.55;
}

/* ── realistic keyboard graphic (SVG) ── */
.kbd-graphic {
    padding: 14px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: linear-gradient(180deg,
        var(--bg-2) 0%,
        color-mix(in srgb, var(--bg-2) 80%, var(--bg) 20%) 100%);
    box-shadow:
        inset 0 1px 0 var(--border),
        0 1px 0 rgba(0,0,0,0.15);
    width: 100%;
    overflow: hidden;
    user-select: none;
}
.kbd-graphic svg.kbd-svg {
    display: block; width: 100%; height: auto;
}
/* All SVG fills/strokes/fonts are set as presentation attributes from JS so
   that highlight + drain colours can be driven directly. Don't add CSS rules
   on .cap / .lbl / .fill — CSS would override the attrs and break the
   pressed/locked states. */

.plot-box .label {
    position: absolute; top: 10px; left: 14px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 10px; letter-spacing: 0.12em; text-transform: uppercase;
    color: var(--muted); z-index: 2; pointer-events: none;
}
.plot-box .label b {
    font-weight: 600; letter-spacing: 0.06em; color: var(--fg);
}

/* ─── Toolbar ─── */
.toolbar {
    display: flex; gap: 10px 14px; flex-wrap: wrap; align-items: center;
    padding: 10px 12px;
    background: var(--bg-panel);
    border: 1px solid var(--border); border-radius: 10px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 11px;
}
.toolbar .pill {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 6px 12px;
    background: var(--pill-bg);
    border: 1px solid var(--border); border-radius: 999px;
    color: var(--text-dim); cursor: pointer;
    text-transform: uppercase; letter-spacing: 0.08em;
    font-size: 10px; transition: all 0.12s; user-select: none;
}
.toolbar .pill:hover { border-color: var(--border-hover); color: var(--fg); }
.toolbar .pill.active {
    background: var(--accent-soft); border-color: var(--accent); color: var(--accent);
}
.toolbar .divider {
    width: 1px; height: 18px; background: var(--border); margin: 0 4px;
}
.toolbar .slider-group {
    display: inline-flex; align-items: center; gap: 10px;
    padding: 4px 8px;
}
.toolbar .slider-group .lab {
    color: var(--muted); font-size: 10px;
    letter-spacing: 0.1em; text-transform: uppercase;
}
.toolbar .slider-group .val {
    color: var(--fg); min-width: 6ch; text-align: right;
}
.toolbar input[type="range"] {
    -webkit-appearance: none; appearance: none;
    width: 130px; height: 4px;
    background: var(--slider-track); border-radius: 999px;
    outline: none;
}
.toolbar input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none; appearance: none;
    width: 14px; height: 14px; border-radius: 50%;
    background: var(--accent); cursor: pointer;
    border: 2px solid var(--bg-2);
}
.toolbar input[type="range"]::-moz-range-thumb {
    width: 14px; height: 14px; border-radius: 50%;
    background: var(--accent); cursor: pointer;
    border: 2px solid var(--bg-2);
}

/* ─── Status readout (next to plots) ─── */
.readout {
    display: flex; gap: 16px; flex-wrap: wrap;
    padding: 10px 14px;
    border: 1px solid var(--border); border-radius: 10px;
    background: var(--bg-panel);
    font-family: 'JetBrains Mono', monospace; font-size: 11px;
}
.readout .item {
    display: flex; flex-direction: column; gap: 2px; min-width: 90px;
}
.readout .item .k {
    color: var(--muted); font-size: 9.5px;
    letter-spacing: 0.16em; text-transform: uppercase;
}
.readout .item .v {
    color: var(--fg); font-size: 14px;
    display: inline-block; transform-origin: left center;
}
.readout .item .v.on  { color: var(--c-high); }
.readout .item .v.off { color: var(--c-low); }
.readout .item .v.warn { color: var(--c-hot); }

/* ─── Plot SVG common styling ─── */
svg.ov text {
    font-family: 'JetBrains Mono', monospace;
    font-size: 12px; fill: var(--muted);
}
svg.ov .grid line { stroke: var(--grid-line); stroke-width: 1; }
svg.ov .grid line.major { stroke: var(--grid-zero); stroke-width: 1.2; }
svg.ov .axis text { fill: var(--muted); font-size: 11px; }
svg.ov .axis line { stroke: var(--tick-line); stroke-width: 1; }
svg.ov .axis path { stroke: var(--tick-line); stroke-width: 1; fill: none; }
svg.ov .axis-title { fill: var(--text-dim); font-size: 11.5px;
    letter-spacing: 0.06em; text-transform: uppercase; }

svg.ov .trace { fill: none; stroke-width: 2.0; stroke-linecap: round; stroke-linejoin: round; }
svg.ov .trace.input  { stroke: var(--c-input); }
svg.ov .trace.output { stroke: var(--c-output); stroke-width: 2.4; }
svg.ov .trace.output2 { stroke: var(--c-output2); stroke-width: 2.2; }

svg.ov .thresh-line {
    stroke: var(--c-thresh); stroke-width: 1.4; stroke-dasharray: 5 4;
    cursor: ns-resize;
}
svg.ov .thresh-grab { fill: var(--c-thresh); cursor: ns-resize; opacity: 0.85; }
svg.ov .thresh-grab:hover { opacity: 1; }
svg.ov .thresh-label { fill: var(--c-thresh); font-size: 11px;
    font-family: 'JetBrains Mono', monospace; }

svg.ov .pulse-mark { fill: var(--c-thresh); opacity: 0.9; }

/* ─── Footer ─── */
footer {
    padding: 60px 56px 80px; text-align: center;
    color: var(--muted); font-size: 13px;
    border-top: 1px solid var(--border);
    font-family: 'JetBrains Mono', monospace;
    letter-spacing: 0.08em; text-transform: uppercase;
}

@media (max-width: 900px) {
    section.scene { grid-template-columns: 1fr; padding: 80px 24px 60px; }
    h1.hero { font-size: 42px; }
    h2 { font-size: 26px; }
    .brand { top: 16px; left: 16px; }
}