:root {
  --bg: #0b0f14;
  --bg-raise: #101720;
  --panel: #121a24;
  --line: #223040;
  --ink: #dfe8ef;
  --ink-dim: #8a9bab;
  --teal: #3fd6c0;
  --teal-dim: #1f6a60;
  --amber: #f2b632;
  --amber-dim: #7a5c1c;
  --red: #ff6b6b;
  --green: #57e08d;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: "IBM Plex Sans", system-ui, -apple-system, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  padding-top: env(safe-area-inset-top, 0px);
  padding-bottom: env(safe-area-inset-bottom, 0px);
}

body {
  background-image:
    radial-gradient(circle at 15% 0%, rgba(63,214,192,0.06), transparent 40%),
    radial-gradient(circle at 85% 20%, rgba(242,182,50,0.05), transparent 35%);
}

.scanline {
  position: fixed; inset: 0; pointer-events: none; z-index: 1;
  background: repeating-linear-gradient(
    to bottom, rgba(255,255,255,0.012) 0px, rgba(255,255,255,0.012) 1px,
    transparent 1px, transparent 3px
  );
}

/* ---------- header ---------- */
.top {
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, var(--bg-raise), var(--bg));
  position: sticky; top: 0; z-index: 5;
  padding-top: env(safe-area-inset-top, 0px);
}
.top-inner {
  max-width: 1180px; margin: 0 auto;
  padding: 18px 24px;
  display: flex; align-items: center; justify-content: space-between; gap: 20px;
  flex-wrap: wrap;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark {
  width: 38px; height: 38px; border-radius: 8px;
  background: linear-gradient(135deg, var(--teal), var(--teal-dim));
  color: #06110f; font-weight: 700; font-family: var(--mono);
  display: flex; align-items: center; justify-content: center; font-size: 20px;
  flex-shrink: 0;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.25; }
.brand-title { font-weight: 600; font-size: 15px; letter-spacing: 0.2px; }
.brand-sub { font-size: 12.5px; color: var(--ink-dim); font-family: var(--mono); }

.scenario {
  display: flex; align-items: baseline; gap: 8px;
  padding: 8px 14px; border: 1px solid var(--line); border-radius: 999px;
  background: var(--panel);
}
.scenario-label { font-size: 10.5px; text-transform: lowercase; color: var(--ink-dim); font-family: var(--mono); }
.scenario-text { font-family: var(--mono); font-size: 13px; color: var(--amber); }

/* ---------- stage / stepper ---------- */
.stage { max-width: 1180px; margin: 0 auto; padding: 28px 24px 60px; }

.pipeline { margin-bottom: 26px; }
.steps {
  display: flex; list-style: none; margin: 0; padding: 0; gap: 6px;
  font-family: var(--mono); font-size: 13px;
}
.steps li {
  flex: 1; display: flex; align-items: center; gap: 10px;
  padding: 10px 14px; border: 1px solid var(--line); border-radius: 10px;
  color: var(--ink-dim); background: var(--panel);
  transition: border-color .2s ease, color .2s ease, background .2s ease;
}
.steps li .n {
  width: 20px; height: 20px; border-radius: 50%; border: 1px solid currentColor;
  display: flex; align-items: center; justify-content: center; font-size: 11px; flex-shrink: 0;
}
.steps li.active { color: var(--teal); border-color: var(--teal-dim); background: rgba(63,214,192,0.06); }
.steps li.done { color: var(--green); border-color: rgba(87,224,141,0.3); }

/* ---------- actors ---------- */
.actors {
  display: grid;
  grid-template-columns: 1fr 0.9fr 1fr;
  gap: 18px;
  align-items: start;
}
@media (max-width: 980px) {
  .actors { grid-template-columns: 1fr; }
  .actor-server { order: 3; }
  #actor-receiver { order: 4; }
}

.actor {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 20px;
  display: flex; flex-direction: column; gap: 14px;
}
.actor-head { display: flex; flex-direction: column; gap: 2px; margin-bottom: 2px; }
.actor-role { font-family: var(--mono); font-size: 11px; color: var(--ink-dim); text-transform: lowercase; }
.actor-head h2 { margin: 0; font-size: 20px; font-weight: 600; }

.block {
  border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px;
  background: rgba(255,255,255,0.015);
}
.block-title { font-size: 11.5px; color: var(--ink-dim); font-family: var(--mono); margin-bottom: 8px; }

.keyrow { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.key-label { font-size: 13.5px; }
.key-status {
  font-family: var(--mono); font-size: 11px; padding: 3px 9px; border-radius: 999px;
  border: 1px solid var(--line); color: var(--ink-dim); white-space: nowrap;
}
.key-status[data-ok="true"] { color: var(--green); border-color: rgba(87,224,141,0.35); }

.fingerprint {
  margin-top: 8px; font-family: var(--mono); font-size: 11px; color: var(--ink-dim);
  word-break: break-all; line-height: 1.5;
}

textarea#message-input {
  width: 100%; resize: vertical; min-height: 56px;
  background: var(--bg); color: var(--ink); border: 1px solid var(--line);
  border-radius: 8px; padding: 10px 12px; font-family: var(--sans); font-size: 14px;
}
textarea#message-input:focus { outline: 2px solid var(--teal-dim); outline-offset: 1px; }

.tamper { display: flex; align-items: center; gap: 9px; font-size: 12.5px; color: var(--ink-dim); cursor: pointer; }
.tamper input { accent-color: var(--red); }

.btn {
  font-family: var(--sans); font-size: 14px; font-weight: 600;
  padding: 11px 16px; border-radius: 9px; border: 1px solid var(--line);
  cursor: pointer; transition: transform .08s ease, border-color .15s ease, opacity .15s ease;
}
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-primary { background: var(--teal); color: #06110f; border-color: var(--teal); }
.btn-primary:hover:not(:disabled) { background: #59e3cf; }
.btn-ghost { background: transparent; color: var(--ink); }
.btn-ghost:hover { border-color: var(--ink-dim); }

.log {
  font-family: var(--mono); font-size: 11.8px; line-height: 1.65;
  color: var(--ink-dim);
  max-height: 190px; overflow-y: auto;
  border-top: 1px dashed var(--line); padding-top: 10px;
  display: flex; flex-direction: column; gap: 2px;
}
.log .l-ok::before { content: "✓ "; color: var(--green); }
.log .l-info::before { content: "· "; color: var(--ink-dim); }
.log .l-warn::before { content: "! "; color: var(--amber); }
.log .l-err::before { content: "✕ "; color: var(--red); }

/* ---------- server (middle actor) ---------- */
.actor-server {
  border-color: rgba(242,182,50,0.25);
  background: linear-gradient(180deg, rgba(242,182,50,0.035), var(--panel) 60%);
}
.actor-server .actor-role { color: var(--amber); }

.packet {
  background: var(--bg-raise); border: 1px solid var(--teal-dim);
  border-radius: 10px; padding: 10px 12px; width: 100%;
  font-family: var(--mono); font-size: 10.5px; color: var(--ink-dim);
}
.packet-row { display: flex; justify-content: space-between; gap: 8px; padding: 3px 0; }
.packet-row span { color: var(--ink-dim); flex-shrink: 0; }
.packet-row code { color: var(--teal); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; max-width: 140px; }

.server-peek {
  border: 1px dashed var(--line); border-radius: 10px; padding: 12px 14px;
  background: rgba(255,255,255,0.015);
}
.server-peek-title { font-size: 12.5px; font-weight: 600; margin-bottom: 6px; color: var(--ink-dim); }
.server-peek-body {
  font-family: var(--mono); font-size: 11px; color: var(--ink-dim);
  word-break: break-all; line-height: 1.6;
}
.server-peek[data-state="blind"] .server-peek-title { color: var(--red); }
.server-peek[data-state="blind"] .server-peek-body { color: var(--red); opacity: 0.85; }

/* ---------- result ---------- */
.result {
  display: flex; gap: 12px; align-items: flex-start;
  border: 1px solid var(--line); border-radius: 10px; padding: 14px;
  background: rgba(255,255,255,0.015);
}
.result-icon {
  flex-shrink: 0; width: 32px; height: 32px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--mono); font-weight: 700; border: 1px solid var(--line); color: var(--ink-dim);
}
.result-title { font-weight: 600; font-size: 14px; margin-bottom: 3px; }
.result-detail { font-size: 12.5px; color: var(--ink-dim); line-height: 1.5; }

.result[data-state="valid"] .result-icon { color: var(--green); border-color: rgba(87,224,141,0.4); background: rgba(87,224,141,0.08); }
.result[data-state="valid"] .result-title { color: var(--green); }
.result[data-state="invalid"] .result-icon { color: var(--red); border-color: rgba(255,107,107,0.4); background: rgba(255,107,107,0.08); }
.result[data-state="invalid"] .result-title { color: var(--red); }

/* ---------- controls ---------- */
.controls { display: flex; gap: 12px; margin: 26px 0; flex-wrap: wrap; }

/* ---------- explainer ---------- */
.explainer {
  border-top: 1px solid var(--line); padding-top: 24px; margin-top: 10px;
}
.explainer h3 { font-size: 15px; margin: 0 0 14px; color: var(--ink); }
.explainer-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 20px;
}
@media (max-width: 700px) { .explainer-grid { grid-template-columns: 1fr; } }
.explainer h4 { font-size: 13px; margin: 0 0 6px; color: var(--teal); font-family: var(--mono); }
.explainer p { font-size: 13.5px; line-height: 1.6; color: var(--ink-dim); margin: 0; }
.explainer-note { margin-top: 16px; font-size: 12px; color: var(--ink-dim); }
.explainer-note code { font-family: var(--mono); background: var(--panel); padding: 1px 6px; border-radius: 4px; }

/* ---------- footer ---------- */
.foot {
  text-align: center; font-size: 11.5px; color: var(--ink-dim);
  padding: 20px; font-family: var(--mono);
}