/* ============================================================
   AETHERIX — BB84 walkthrough page + animated journey simulator
   Scoped under .bb84 so nothing leaks into the rest of the site.
   Colour semantics (shared with frontend/src/components/BB84Journey.tsx):
     Z basis  = accent / cyan      X basis  = quantum / purple
     kept     = success green      discard  = muted grey
     Eve/error= danger red
   ============================================================ */

.bb84 {
    --z: var(--accent);
    --x: var(--quantum);
    --keep: var(--success);
    --drop: var(--text-muted);
    --bad: var(--danger);
}

/* ---------- polarization chips ---------------------------------- */

.pol {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    font-family: var(--font-mono);
    font-size: 1rem;
    font-weight: 700;
    line-height: 1;
    border: 1.5px solid currentColor;
    flex-shrink: 0;
}

.pol-z { color: var(--z); background: rgba(var(--accent-rgb), 0.12); }
.pol-x { color: var(--x); background: rgba(var(--quantum-rgb), 0.12); }
.pol-sm { width: 24px; height: 24px; font-size: 0.85rem; }

.basis-tag {
    display: inline-block;
    min-width: 20px;
    padding: 1px 7px;
    border-radius: 5px;
    font-family: var(--font-mono);
    font-size: 0.74rem;
    font-weight: 700;
    text-align: center;
}

.basis-z { color: var(--z); background: rgba(var(--accent-rgb), 0.14); }
.basis-x { color: var(--x); background: rgba(var(--quantum-rgb), 0.14); }

/* ---------- worked-example tables -------------------------------- */

.bb84-table-wrap { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--border); }
.bb84-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; min-width: 520px; }
.bb84-table th {
    position: static;
    padding: 10px 12px;
    text-align: center;
    white-space: nowrap;
    /* The global `th` uses --text-muted, which at 0.68rem uppercase is very
       faint against the dark starfield on small screens. */
    color: var(--text-secondary);
    font-size: 0.7rem;
}
.bb84-table th:first-child { text-align: left; }
.bb84-table td { padding: 9px 12px; text-align: center; vertical-align: middle; }
.bb84-table td:first-child { text-align: left; color: var(--text-secondary); font-family: var(--font); }
.bb84-table tr.row-keep td { background: rgba(var(--success-rgb), 0.06); }
.bb84-table tr.row-drop td { color: var(--text-muted); }
.bb84-table tr.row-drop .pol { opacity: 0.45; }

.verdict-keep { color: var(--keep); font-weight: 700; }
.verdict-drop { color: var(--drop); font-weight: 700; }

/* ---------- key strips ------------------------------------------- */

.bitstrip { display: flex; flex-wrap: wrap; gap: 5px; margin-top: 10px; }

.bit {
    width: 26px;
    height: 26px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    font-weight: 700;
    background: rgba(var(--quantum-rgb), 0.1);
    border: 1px solid var(--border);
    color: var(--text-secondary);
}

.bit.on { background: rgba(var(--success-rgb), 0.14); border-color: rgba(var(--success-rgb), 0.4); color: var(--keep); }
.bit.err { background: rgba(var(--danger-rgb), 0.16); border-color: rgba(var(--danger-rgb), 0.5); color: var(--bad); }
.bit.gone { opacity: 0.3; text-decoration: line-through; }

/* ---------- probability tree ------------------------------------- */

.prob-tree {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-top: 14px;
}

.prob-node {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 16px;
    background: rgba(var(--quantum-rgb), 0.04);
}

.prob-node .p {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    display: block;
}

.prob-node.result { grid-column: 1 / -1; border-color: rgba(var(--danger-rgb), 0.4); background: rgba(var(--danger-rgb), 0.07); }
.prob-node.result .p { color: var(--bad); font-size: 2rem; }

/* ---------- the animated journey --------------------------------- */

.bb84-sim {
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: var(--bg-card);
    padding: 18px;
    margin-top: 16px;
}

.bb84-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 10px 14px;
    align-items: center;
    padding-bottom: 14px;
    margin-bottom: 16px;
    border-bottom: 1px solid var(--border);
}

.bb84-ctl { display: flex; align-items: center; gap: 7px; font-size: 0.78rem; color: var(--text-secondary); }
.bb84-ctl select,
.bb84-ctl input[type="range"] {
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.78rem;
    padding: 5px 8px;
}
.bb84-ctl input[type="range"] { padding: 0; width: 96px; accent-color: var(--accent); }

.bb84-eve-toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    border-radius: 20px;
    border: 1px solid var(--border);
    background: var(--bg-input);
    color: var(--text-secondary);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}
.bb84-eve-toggle:hover { border-color: var(--border-bright); }
.bb84-eve-toggle.armed {
    border-color: rgba(var(--danger-rgb), 0.55);
    background: rgba(var(--danger-rgb), 0.12);
    color: var(--bad);
}

/* stage rows ------------------------------------------------------ */

.bb84-row {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 13px 16px;
    background: rgba(var(--quantum-rgb), 0.035);
}

.bb84-row-head {
    display: flex;
    align-items: center;
    gap: 9px;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 1.1px;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 8px;
}
.bb84-row-head .who { color: var(--text-primary); letter-spacing: 0.4px; font-size: 0.86rem; text-transform: none; }
.bb84-row-head .tail { margin-left: auto; font-family: var(--font-mono); letter-spacing: 0; text-transform: none; color: var(--text-secondary); }

.bb84-row.alice { border-color: rgba(var(--accent-rgb), 0.3); }
.bb84-row.bob { border-color: rgba(var(--success-rgb), 0.28); }
.bb84-row.eve { border-color: rgba(var(--danger-rgb), 0.45); background: rgba(var(--danger-rgb), 0.07); }
.bb84-row.eve.off { display: none; }
.bb84-row.key { border-color: rgba(var(--success-rgb), 0.45); background: rgba(var(--success-rgb), 0.07); }
.bb84-row.abort { border-color: rgba(var(--danger-rgb), 0.55); background: rgba(var(--danger-rgb), 0.1); }

/* the arrow connectors between rows */
.bb84-link {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 9px;
    font-size: 0.7rem;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--text-muted);
    padding: 7px 0;
}
.bb84-link::before,
.bb84-link::after {
    content: "";
    flex: 1;
    max-width: 90px;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--border-bright), transparent);
}

/* quantum channel — where photons actually fall ------------------- */

.bb84-channel {
    position: relative;
    height: 190px;
    margin: 4px 0;
    border-radius: var(--radius);
    border: 1px dashed rgba(var(--quantum-rgb), 0.3);
    background:
        linear-gradient(180deg, rgba(var(--accent-rgb), 0.05), rgba(var(--quantum-rgb), 0.02) 50%, rgba(var(--success-rgb), 0.05));
    overflow: hidden;
}

.bb84-channel-label {
    position: absolute;
    top: 8px;
    left: 12px;
    font-size: 0.68rem;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    color: var(--text-muted);
    pointer-events: none;
}

.bb84-channel.has-eve { border-color: rgba(var(--danger-rgb), 0.45); }

/* Eve's interception band, drawn across the middle of the channel */
.bb84-eve-band {
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    height: 34px;
    display: none;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 1.4px;
    text-transform: uppercase;
    color: var(--bad);
    background: repeating-linear-gradient(
        45deg,
        rgba(var(--danger-rgb), 0.14) 0 8px,
        rgba(var(--danger-rgb), 0.05) 8px 16px);
    border-top: 1px solid rgba(var(--danger-rgb), 0.45);
    border-bottom: 1px solid rgba(var(--danger-rgb), 0.45);
    pointer-events: none;
}
.bb84-channel.has-eve .bb84-eve-band { display: flex; }

.photon {
    position: absolute;
    width: 30px;
    height: 30px;
    margin-left: -15px;
    margin-top: -15px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mono);
    font-size: 1rem;
    font-weight: 700;
    border: 1.5px solid currentColor;
    will-change: transform;
    pointer-events: none;
}

.photon.b-z { color: var(--z); background: rgba(var(--accent-rgb), 0.16); box-shadow: 0 0 12px rgba(var(--accent-rgb), 0.35); }
.photon.b-x { color: var(--x); background: rgba(var(--quantum-rgb), 0.16); box-shadow: 0 0 12px rgba(var(--quantum-rgb), 0.35); }
.photon.tampered { box-shadow: 0 0 14px rgba(var(--danger-rgb), 0.6); }

.photon-tag {
    position: absolute;
    top: -13px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.58rem;
    font-family: var(--font-mono);
    color: var(--text-muted);
    letter-spacing: 0;
}

/* narration strip -------------------------------------------------- */

.bb84-narration {
    margin-top: 12px;
    padding: 11px 14px;
    border-radius: var(--radius);
    background: var(--code-bg);
    border-left: 3px solid var(--border-bright);
    font-family: var(--font-mono);
    font-size: 0.78rem;
    line-height: 1.65;
    color: var(--text-secondary);
    min-height: 62px;
}
.bb84-narration b { color: var(--text-primary); font-weight: 600; }
.bb84-narration .kept { color: var(--keep); }
.bb84-narration .dropped { color: var(--drop); }
.bb84-narration .bad { color: var(--bad); }

/* live counters ---------------------------------------------------- */

.bb84-stats {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 10px;
    margin-top: 14px;
}

.bb84-stat {
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 9px 11px;
    background: var(--bg-input);
}
.bb84-stat .k {
    font-size: 0.6rem;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--text-muted);
    display: block;
    white-space: nowrap;
}
.bb84-stat .v {
    font-family: var(--font-mono);
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
}
.bb84-stat.good .v { color: var(--keep); }
.bb84-stat.warn .v { color: var(--warning); }
.bb84-stat.bad .v { color: var(--bad); }

/* sifting bins ------------------------------------------------------ */

.bb84-bins { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

.bb84-bin {
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 10px 12px;
    min-height: 74px;
}
.bb84-bin.keep { border-color: rgba(var(--success-rgb), 0.35); background: rgba(var(--success-rgb), 0.05); }
.bb84-bin.drop { background: var(--code-bg); }
.bb84-bin-head {
    font-size: 0.66rem;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 7px;
    display: flex;
    justify-content: space-between;
}
.bb84-bin .bitstrip { margin-top: 0; gap: 4px; }
.bb84-bin .bit { width: 21px; height: 21px; font-size: 0.68rem; border-radius: 4px; }

/* QBER meter --------------------------------------------------------- */

.qber-meter {
    position: relative;
    height: 26px;
    border-radius: 13px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    overflow: hidden;
}
.qber-fill {
    height: 100%;
    width: 0;
    border-radius: 13px 0 0 13px;
    background: linear-gradient(90deg, var(--success), var(--warning));
    transition: width 0.35s var(--ease-out), background 0.35s var(--ease-out);
}
.qber-fill.over { background: linear-gradient(90deg, var(--warning), var(--danger)); }

.qber-threshold {
    position: absolute;
    top: -3px;
    bottom: -3px;
    width: 2px;
    background: var(--danger);
    left: 44%; /* 11% of a 0–25% scale */
}
.qber-threshold::after {
    content: "11%";
    position: absolute;
    top: -16px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.6rem;
    font-family: var(--font-mono);
    color: var(--danger);
    white-space: nowrap;
}
.qber-scale {
    display: flex;
    justify-content: space-between;
    font-size: 0.6rem;
    font-family: var(--font-mono);
    color: var(--text-muted);
    margin-top: 4px;
}

/* compression bar ---------------------------------------------------- */

.shrink-bar { display: flex; align-items: center; gap: 10px; margin-top: 8px; }
.shrink-track {
    flex: 1;
    height: 22px;
    border-radius: 6px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    position: relative;
    overflow: hidden;
}
.shrink-seg {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    transition: width 0.4s var(--ease-out);
}
.shrink-seg.total { width: 100%; background: rgba(var(--quantum-rgb), 0.22); }
.shrink-seg.leak { background: rgba(var(--warning-rgb), 0.4); }
.shrink-seg.final { background: rgba(var(--success-rgb), 0.5); }
.shrink-legend { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 8px; font-size: 0.72rem; color: var(--text-secondary); }
.shrink-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 5px; }

/* final key ------------------------------------------------------------ */

.bb84-key-out {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--keep);
    word-break: break-all;
    line-height: 1.6;
    margin-top: 6px;
}

/* pipeline diagram ----------------------------------------------------- */

.pipe {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    margin-top: 14px;
}
.pipe-box {
    width: 100%;
    max-width: 340px;
    text-align: center;
    padding: 10px 14px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    background: rgba(var(--quantum-rgb), 0.05);
    font-size: 0.82rem;
}
.pipe-box strong { display: block; color: var(--text-primary); }
.pipe-box small { color: var(--text-muted); font-size: 0.72rem; }
.pipe-box.q { border-color: rgba(var(--quantum-rgb), 0.45); background: rgba(var(--quantum-rgb), 0.1); }
.pipe-box.danger { border-color: rgba(var(--danger-rgb), 0.45); background: rgba(var(--danger-rgb), 0.09); }
.pipe-box.ok { border-color: rgba(var(--success-rgb), 0.45); background: rgba(var(--success-rgb), 0.09); }
.pipe-arrow { color: var(--text-muted); font-size: 1.1rem; line-height: 1; padding: 5px 0; }
.pipe-split { display: flex; gap: 16px; width: 100%; max-width: 520px; justify-content: center; }
.pipe-split > div { flex: 1; display: flex; flex-direction: column; align-items: center; }

/* responsive ------------------------------------------------------------ */

@media (max-width: 900px) {
    .bb84-stats { grid-template-columns: repeat(3, 1fr); }
    .prob-tree { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
    .bb84-bins { grid-template-columns: 1fr; }
    .bb84-stats { grid-template-columns: repeat(2, 1fr); }
    .bb84-channel { height: 160px; }
    .pipe-split { flex-direction: column; align-items: center; }
}

@media (prefers-reduced-motion: reduce) {
    .photon { transition: none !important; }
    .qber-fill, .shrink-seg { transition: none !important; }
}