:root {
  --bg: #042f2e;
  --panel: #0f3d3b;
  --mint: #99f6e4;
  --mint-dim: #2dd4bf;
  --bubble-in: #134e4a;
  --bubble-out: #115e59;
  --ink: #f0fdfa;
  --muted: #ccfbf1;
  --warn: #fde68a;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: auto;
}

body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.7;
}

a {
  color: var(--mint);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.frame {
  width: min(1080px, calc(100% - 32px));
  margin: 0 auto;
}

.head {
  background: #023533;
  border-bottom: 4px solid var(--mint-dim);
}

.head-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--mint);
  font-weight: 700;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 14px;
}

.nav a {
  font-size: 14px;
}

.hero {
  padding: 40px 0 20px;
}

.hero h1 {
  margin: 0 0 14px;
  font-size: clamp(26px, 3.8vw, 36px);
  line-height: 1.3;
}

.hero p {
  margin: 0 0 8px;
  max-width: 44em;
  color: var(--muted);
}

.bubbles {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin: 0 0 36px;
}

.bubble {
  max-width: 78%;
  padding: 14px 16px;
  background: var(--bubble-in);
}

.bubble.me {
  align-self: flex-end;
  background: var(--bubble-out);
  border-radius: 18px 4px 18px 18px;
}

.bubble.them {
  align-self: flex-start;
  border-radius: 4px 18px 18px 18px;
}

.bubble h2,
.bubble h3 {
  margin: 0 0 8px;
  font-size: 18px;
  color: var(--mint);
}

.bubble p {
  margin: 0 0 8px;
}

.bubble p:last-child {
  margin-bottom: 0;
}

.mention {
  border-left: 4px solid var(--warn);
  padding-left: 10px;
  color: var(--warn);
  margin: 0 0 8px;
  font-size: 14px;
}

.steps-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin: 0 0 36px;
}

.steps-row article {
  background: var(--panel);
  border-radius: 4px 16px 16px 16px;
  padding: 14px;
}

.steps-row span {
  display: block;
  color: var(--mint-dim);
  font-size: 12px;
  margin-bottom: 6px;
}

.steps-row h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.steps-row p {
  margin: 0;
  font-size: 14px;
  color: var(--muted);
}

.block {
  margin: 0 0 36px;
}

.block > h2 {
  margin: 0 0 12px;
  font-size: 24px;
}

.block > p {
  margin: 0 0 12px;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: var(--panel);
}

th,
td {
  border: 1px solid #115e59;
  padding: 10px 12px;
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--mint);
}

.pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.preview-bar {
  background: #023533;
  border-radius: 16px 16px 4px 16px;
  padding: 12px 16px;
  margin: 12px 0;
  color: var(--warn);
}

details {
  background: var(--bubble-in);
  border-radius: 4px 18px 18px 18px;
  margin: 0 0 10px;
  padding: 4px 8px;
}

summary {
  cursor: pointer;
  padding: 10px;
  font-weight: 600;
  color: var(--mint);
}

details p {
  margin: 0;
  padding: 0 10px 12px;
  color: var(--muted);
}

.foot {
  background: #023533;
  border-top: 4px solid var(--mint-dim);
  padding: 24px 0 32px;
  color: #99f6e4;
  font-size: 14px;
}

.foot p {
  margin: 0 0 8px;
}

@media (max-width: 860px) {
  .head-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .steps-row,
  .pair {
    grid-template-columns: 1fr;
  }

  .bubble {
    max-width: 100%;
  }
}