/* ============================================
   CRC16 在线工具 - 样式表
   纯静态，无外部依赖
   ============================================ */

:root {
  --bg: #0b0f14;
  --bg-soft: #111820;
  --panel: #141c26;
  --panel-2: #182231;
  --border: #24303d;
  --border-soft: #1c2634;
  --text: #dbe4ee;
  --text-dim: #9aa9ba;
  --muted: #6f7f91;
  --accent: #2dd4bf;
  --accent-dim: rgba(45, 212, 191, 0.12);
  --blue: #4fb8f5;
  --danger: #f87171;
  --danger-dim: rgba(248, 113, 113, 0.12);
  --ok: #4ade80;
  --ok-dim: rgba(74, 222, 128, 0.12);
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --radius: 10px;
  --maxw: 1080px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 15px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

/* ---------- 顶部导航 ---------- */
.site-header {
  border-bottom: 1px solid var(--border-soft);
  background: rgba(11, 15, 20, 0.92);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 40;
}
.nav {
  display: flex;
  align-items: center;
  gap: 22px;
  height: 58px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-weight: 700;
  color: var(--text);
  font-size: 15.5px;
  letter-spacing: -0.2px;
  white-space: nowrap;
}
.brand:hover { text-decoration: none; }
.brand-mark {
  width: 26px; height: 26px;
  border-radius: 7px;
  background: linear-gradient(135deg, var(--accent), #16948a);
  display: grid; place-items: center;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  color: #04211e;
  flex: none;
}
.nav-links { display: flex; gap: 4px; margin-left: auto; align-items: center; }
.nav-links a {
  color: var(--text-dim);
  font-size: 14px;
  padding: 7px 11px;
  border-radius: 7px;
  white-space: nowrap;
}
.nav-links a:hover { color: var(--text); background: var(--panel); text-decoration: none; }
.nav-links a.active { color: var(--accent); background: var(--accent-dim); }
.nav-cta {
  border: 1px solid var(--border);
  color: var(--text) !important;
  font-weight: 500;
}
.nav-cta:hover { border-color: var(--accent); color: var(--accent) !important; }

/* ---------- 页头标题 ---------- */
.page-head { padding: 42px 0 26px; }
.page-head h1 {
  font-size: 30px;
  line-height: 1.3;
  margin: 0 0 10px;
  letter-spacing: -0.7px;
  font-weight: 700;
}
.page-head p {
  margin: 0;
  color: var(--text-dim);
  font-size: 15px;
  max-width: 720px;
}
.page-head.compact { padding: 34px 0 22px; }
.page-head.compact h1 { font-size: 24px; }

.tag-row { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 14px; }
.tag {
  font-size: 12px;
  font-family: var(--mono);
  color: var(--text-dim);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 10px;
  background: var(--bg-soft);
}

/* ---------- 计算器 ---------- */
.calc {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px;
  margin-bottom: 20px;
}

.calc-row {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

.field label {
  display: block;
  font-size: 12.5px;
  color: var(--muted);
  margin-bottom: 7px;
  font-weight: 500;
  letter-spacing: 0.2px;
}

select, textarea, input[type="text"] {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--mono);
  font-size: 14px;
  padding: 11px 12px;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}
select { font-family: inherit; cursor: pointer; }
select:focus, textarea:focus, input[type="text"]:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-dim);
}
textarea {
  resize: vertical;
  min-height: 96px;
  line-height: 1.65;
  letter-spacing: 0.6px;
}
textarea::placeholder { color: #4a5866; }

/* 输入模式切换 */
.seg {
  display: inline-flex;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
  gap: 2px;
}
.seg button {
  border: 0;
  background: transparent;
  color: var(--text-dim);
  font-size: 13px;
  font-family: inherit;
  padding: 5px 13px;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.15s;
}
.seg button.on { background: var(--accent-dim); color: var(--accent); font-weight: 600; }

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 10px 0 4px;
}
.toolbar .spacer { flex: 1 1 auto; }

.chip {
  font-size: 12.5px;
  font-family: var(--mono);
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: 7px;
  padding: 5px 10px;
  cursor: pointer;
  transition: all 0.15s;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }

.btn {
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-family: inherit;
  font-size: 13.5px;
  padding: 8px 15px;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.15s;
  white-space: nowrap;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #04211e;
  font-weight: 600;
}
.btn.primary:hover { background: #38e0ca; color: #04211e; }
.btn.ghost { background: transparent; }

/* ---------- 结果区 ---------- */
.result {
  margin-top: 18px;
  border-top: 1px dashed var(--border);
  padding-top: 18px;
}
.result-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 14px;
}
.res-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 13px 15px;
  min-width: 0;
}
.res-card .k {
  font-size: 11.5px;
  color: var(--muted);
  letter-spacing: 0.4px;
  margin-bottom: 5px;
  text-transform: uppercase;
}
.res-card .v {
  font-family: var(--mono);
  font-size: 20px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.5px;
  word-break: break-all;
  line-height: 1.35;
}
.res-card .v.small { font-size: 15px; color: var(--text); }
.res-card .sub {
  font-size: 11.5px;
  color: var(--muted);
  font-family: var(--mono);
  margin-top: 4px;
  word-break: break-all;
}

.frame-box {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 13px 15px;
  margin-bottom: 12px;
}
.frame-box .k {
  font-size: 11.5px;
  color: var(--muted);
  letter-spacing: 0.4px;
  text-transform: uppercase;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.frame-box code {
  font-family: var(--mono);
  font-size: 15px;
  line-height: 1.9;
  color: var(--text);
  word-break: break-all;
  letter-spacing: 0.8px;
}
.frame-box code .add { color: var(--accent); font-weight: 600; }

/* 校验提示 */
.verify {
  border-radius: var(--radius);
  padding: 11px 14px;
  font-size: 13.5px;
  display: flex;
  gap: 9px;
  align-items: flex-start;
  line-height: 1.6;
}
.verify .ico { font-weight: 700; flex: none; }
.verify.ok { background: var(--ok-dim); border: 1px solid rgba(74,222,128,0.3); color: #b7f5c9; }
.verify.ok .ico { color: var(--ok); }
.verify.bad { background: var(--danger-dim); border: 1px solid rgba(248,113,113,0.3); color: #fbc5c5; }
.verify.bad .ico { color: var(--danger); }
.verify.info { background: var(--bg); border: 1px solid var(--border); color: var(--text-dim); }
.verify.info .ico { color: var(--muted); }
.verify code { font-family: var(--mono); background: rgba(255,255,255,0.06); padding: 1px 5px; border-radius: 4px; }

/* ---------- 内容区块 ---------- */
.section { margin: 44px 0; }
.section h2 {
  font-size: 21px;
  margin: 0 0 6px;
  letter-spacing: -0.4px;
  font-weight: 700;
}
.section .lead {
  color: var(--text-dim);
  font-size: 14.5px;
  margin: 0 0 18px;
  max-width: 760px;
}
.section h3 {
  font-size: 16px;
  margin: 24px 0 8px;
  color: var(--text);
  font-weight: 600;
}
.section p { color: var(--text-dim); margin: 0 0 12px; }
.section ul, .section ol { color: var(--text-dim); padding-left: 20px; margin: 0 0 14px; }
.section li { margin-bottom: 6px; }

/* ---------- 表格 ---------- */
.table-scroll { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
  min-width: 660px;
}
th, td {
  text-align: left;
  padding: 10px 13px;
  border-bottom: 1px solid var(--border-soft);
  white-space: nowrap;
}
th {
  background: var(--panel-2);
  color: var(--text-dim);
  font-weight: 600;
  font-size: 12.5px;
  letter-spacing: 0.2px;
}
td { color: var(--text-dim); }
td.mono, th.mono { font-family: var(--mono); }
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover td { background: rgba(45, 212, 191, 0.04); }
td .hl { color: var(--accent); font-family: var(--mono); }

/* ---------- 帧结构可视化 ---------- */
.frame-visual {
  display: grid;
  grid-template-columns: 1fr 1fr 1.6fr 1fr;
  gap: 6px;
  margin: 14px 0 6px;
}
.fv-cell {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 8px;
  text-align: center;
  min-width: 0;
}
.fv-cell .fv-t {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}
.fv-cell .fv-v {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--muted);
}
.fv-cell.crc { border-color: rgba(45,212,191,0.45); }
.fv-cell.crc .fv-t { color: var(--accent); }

@media (max-width: 560px) {
  .frame-visual { grid-template-columns: 1fr 1fr; }
  .fv-cell { padding: 9px 6px; }
}

/* ---------- 提示卡片 ---------- */
.note {
  border-left: 3px solid var(--accent);
  background: var(--accent-dim);
  padding: 12px 16px;
  border-radius: 0 8px 8px 0;
  color: var(--text-dim);
  font-size: 14px;
  margin: 16px 0;
}
.note strong { color: var(--text); }

.code-block {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.75;
  color: #b9c7d6;
  margin: 12px 0 18px;
  white-space: pre;
  letter-spacing: 0.4px;
}
.code-block .c { color: #5e7080; }
.code-block .k { color: var(--blue); }
.code-block .s { color: #a5d6a7; }
.code-block .n { color: #ffcc80; }

/* ---------- 推广页 ---------- */
.hero-service {
  padding: 46px 0 10px;
  border-bottom: 1px solid var(--border-soft);
}
.hero-service h1 {
  font-size: 33px;
  line-height: 1.25;
  margin: 0 0 14px;
  letter-spacing: -0.9px;
  font-weight: 700;
}
.hero-service h1 em {
  font-style: normal;
  color: var(--accent);
}
.hero-service .sub {
  color: var(--text-dim);
  font-size: 16px;
  max-width: 700px;
  margin: 0 0 26px;
}

.contact-card {
  background: linear-gradient(135deg, rgba(45,212,191,0.1), rgba(79,184,245,0.06));
  border: 1px solid rgba(45, 212, 191, 0.32);
  border-radius: 14px;
  padding: 24px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 20px;
  margin: 26px 0 10px;
}
.contact-card .cl { flex: 1 1 260px; min-width: 0; }
.contact-card .cl .t {
  font-size: 12.5px;
  color: var(--muted);
  letter-spacing: 0.5px;
  margin-bottom: 6px;
}
.contact-card .qq {
  font-family: var(--mono);
  font-size: 30px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 2px;
  line-height: 1.2;
  user-select: all;
}
.contact-card .hint {
  font-size: 13px;
  color: var(--text-dim);
  margin-top: 7px;
}

.svc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 14px;
  margin: 18px 0 8px;
}
.svc {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 18px 19px;
}
.svc h3 {
  margin: 0 0 8px;
  font-size: 15.5px;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}
.svc h3 .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent); flex: none;
}
.svc p { margin: 0; font-size: 13.5px; color: var(--text-dim); line-height: 1.65; }
.svc ul { margin: 8px 0 0; padding-left: 17px; font-size: 13.5px; }

.steps { counter-reset: st; margin: 20px 0; padding: 0; list-style: none; }
.steps li {
  counter-increment: st;
  position: relative;
  padding-left: 42px;
  margin-bottom: 16px;
  color: var(--text-dim);
  font-size: 14.5px;
}
.steps li::before {
  content: counter(st);
  position: absolute;
  left: 0; top: 1px;
  width: 27px; height: 27px;
  border-radius: 50%;
  background: var(--accent-dim);
  border: 1px solid rgba(45,212,191,0.3);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  display: grid; place-items: center;
}
.steps li b { color: var(--text); display: block; margin-bottom: 2px; }

/* ---------- 页脚 ---------- */
.site-footer {
  border-top: 1px solid var(--border-soft);
  margin-top: 60px;
  padding: 26px 0 34px;
  color: var(--muted);
  font-size: 13px;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 26px;
  align-items: center;
  justify-content: space-between;
}
.footer-inner a { color: var(--text-dim); }
.footer-inner a:hover { color: var(--accent); }
.footer-links { display: flex; gap: 18px; flex-wrap: wrap; }

/* ---------- 复制提示 ---------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: 34px;
  transform: translateX(-50%) translateY(14px);
  background: var(--accent);
  color: #04211e;
  font-size: 13.5px;
  font-weight: 600;
  padding: 9px 20px;
  border-radius: 999px;
  opacity: 0;
  pointer-events: none;
  transition: all 0.22s ease;
  z-index: 99;
  box-shadow: 0 8px 26px rgba(0,0,0,0.45);
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ---------- 响应式 ---------- */
@media (max-width: 860px) {
  .calc-row { grid-template-columns: 1fr; }
  .result-grid { grid-template-columns: 1fr 1fr; }
  .page-head h1 { font-size: 25px; }
  .hero-service h1 { font-size: 26px; }
  .hero-service .sub { font-size: 15px; }
  .contact-card .qq { font-size: 25px; }
}

@media (max-width: 560px) {
  body { font-size: 14.5px; }
  .wrap { padding: 0 15px; }
  .nav { gap: 10px; height: 54px; }
  .nav-links { gap: 0; }
  .nav-links a { padding: 6px 8px; font-size: 13px; }
  .brand span.full { display: none; }
  .calc { padding: 16px; border-radius: 12px; }
  .result-grid { grid-template-columns: 1fr; }
  .page-head { padding: 28px 0 18px; }
  .page-head h1 { font-size: 22px; letter-spacing: -0.4px; }
  .section { margin: 34px 0; }
  .section h2 { font-size: 18.5px; }
  .contact-card { padding: 18px; }
  .res-card .v { font-size: 18px; }
  .frame-box code { font-size: 13.5px; }
}