:root {
  --bg: #05060a;
  --bg-soft: #080a10;
  --panel: rgba(12, 16, 24, 0.72);
  --line: rgba(120, 160, 190, 0.14);
  --text: #e8eef6;
  --muted: #93a2b8;
  --dim: #63728a;
  --accent: #5eead4;
  --accent-2: #38bdf8;
  --danger: #f87171;
  --mono: "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", Menlo, monospace;
  --sans: "Inter", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.nav-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(900px 520px at 10% -8%, rgba(56, 189, 248, 0.12), transparent 62%),
    radial-gradient(760px 480px at 92% 2%, rgba(139, 92, 246, 0.1), transparent 60%),
    radial-gradient(900px 620px at 50% 108%, rgba(94, 234, 212, 0.06), transparent 68%);
}

.wrap { width: 100%; max-width: 1240px; margin: 0 auto; padding: 0 28px; }

a { color: inherit; text-decoration: none; }
button { font-family: inherit; }
h1 { margin: 0; font-size: 26px; letter-spacing: -0.02em; }

/* ---------- header ---------- */
.nav-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(5, 6, 10, 0.86);
  backdrop-filter: blur(14px);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 11px; }
.brand-mark { width: 28px; height: 28px; color: var(--accent); flex: none; filter: drop-shadow(0 0 10px rgba(94, 234, 212, 0.35)); }
.brand-mark svg { width: 100%; height: 100%; display: block; }
.brand-text { display: flex; flex-direction: column; line-height: 1.1; }
.brand-text strong { font-family: var(--mono); font-size: 10px; font-weight: 500; letter-spacing: 0.1em; color: var(--muted); }
.brand-text small { font-size: 13px; font-weight: 600; margin-top: 5px; letter-spacing: 0.04em; }

.header-right { display: flex; align-items: center; gap: 12px; }
.header-tag {
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.26em;
  color: var(--dim);
}
.session { font-size: 12px; color: var(--muted); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 38px;
  padding: 0 18px;
  border-radius: 9px;
  border: 1px solid transparent;
  font-size: 13.5px;
  font-weight: 500;
  cursor: pointer;
  transition: border-color 0.22s ease, background 0.22s ease, color 0.22s ease, transform 0.18s ease;
  background: transparent;
  color: var(--text);
}
.btn-sm { height: 32px; padding: 0 13px; font-size: 12.5px; }
.btn-block { width: 100%; height: 44px; font-size: 14.5px; }
.btn-primary { background: var(--accent); color: #04211c; border-color: var(--accent); }
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 14px 30px -14px rgba(94, 234, 212, 0.8); }
.btn-ghost { border-color: var(--line); color: var(--muted); }
.btn-ghost:hover { color: var(--text); border-color: rgba(94, 234, 212, 0.42); }
.btn-outline { border-color: rgba(120, 160, 190, 0.28); color: var(--text); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn[disabled] { opacity: 0.55; cursor: not-allowed; transform: none; }

/* ---------- main ---------- */
.nav-main { position: relative; z-index: 1; padding-top: 46px; padding-bottom: 80px; }

/* login */
.login-view { display: grid; place-items: center; min-height: calc(100vh - 200px); }
.login-card {
  width: 100%;
  max-width: 420px;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 38px 34px 32px;
  background: linear-gradient(168deg, rgba(13, 18, 26, 0.94), rgba(7, 9, 14, 0.97));
  box-shadow: 0 40px 90px -60px rgba(56, 189, 248, 0.55);
}
.login-tag { margin: 0 0 14px; font-family: var(--mono); font-size: 9px; letter-spacing: 0.28em; color: var(--accent-2); }
.login-card h1 { font-size: 24px; }
.login-sub { margin: 12px 0 28px; font-size: 13px; color: var(--muted); line-height: 1.75; }

.field { display: flex; flex-direction: column; gap: 8px; margin-bottom: 16px; }
.field > span { font-size: 12px; color: var(--muted); letter-spacing: 0.04em; }
.field input {
  width: 100%;
  background: rgba(5, 7, 11, 0.72);
  border: 1px solid rgba(120, 160, 190, 0.18);
  border-radius: 9px;
  color: var(--text);
  font-family: inherit;
  font-size: 14px;
  padding: 12px 14px;
  outline: none;
  transition: border-color 0.22s ease, box-shadow 0.22s ease;
}
.field input::placeholder { color: #4a566b; }
.field input:focus { border-color: rgba(94, 234, 212, 0.6); box-shadow: 0 0 0 3px rgba(94, 234, 212, 0.1); }
.login-error { min-height: 18px; margin: 12px 0 0; font-size: 12.5px; color: var(--danger); }

/* board */
.board-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 32px; flex-wrap: wrap; margin-bottom: 26px; }
.board-tag { margin: 0 0 12px; font-family: var(--mono); font-size: 9px; letter-spacing: 0.28em; color: var(--accent-2); }
.board-sub { margin: 10px 0 0; font-size: 13px; color: var(--muted); }
.board-tools { display: flex; align-items: center; gap: 10px; }
.search {
  width: 280px;
  height: 38px;
  padding: 0 14px;
  border-radius: 9px;
  border: 1px solid var(--line);
  background: rgba(8, 11, 17, 0.85);
  color: var(--text);
  font-family: inherit;
  font-size: 13.5px;
  outline: none;
  transition: border-color 0.22s ease;
}
.search::placeholder { color: #4a566b; }
.search:focus { border-color: rgba(94, 234, 212, 0.55); }

.cat-filter { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 30px; }
.chip {
  height: 32px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(9, 12, 18, 0.7);
  color: var(--muted);
  font-size: 12.5px;
  cursor: pointer;
  transition: all 0.22s ease;
}
.chip em { font-family: var(--mono); font-style: normal; font-size: 10px; color: var(--dim); margin-left: 6px; }
.chip:hover { color: var(--text); border-color: rgba(94, 234, 212, 0.36); }
.chip.active { background: rgba(94, 234, 212, 0.1); border-color: rgba(94, 234, 212, 0.5); color: var(--accent); }
.chip.active em { color: rgba(94, 234, 212, 0.75); }

.board { display: flex; flex-direction: column; gap: 34px; }

.cat-section { scroll-margin-top: 90px; }
.cat-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
}
.cat-head h2 { margin: 0; font-size: 15px; font-weight: 600; letter-spacing: 0.02em; }
.cat-head span { font-family: var(--mono); font-size: 10px; letter-spacing: 0.16em; color: var(--dim); }

.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(268px, 1fr)); gap: 12px; }

.card {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 13px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(9, 12, 18, 0.82);
  transition: border-color 0.24s ease, background 0.24s ease, transform 0.2s ease;
  overflow: hidden;
}
.card::after {
  content: "";
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--accent), rgba(56, 189, 248, 0.4));
  opacity: 0;
  transition: opacity 0.24s ease;
}
.card:hover {
  border-color: rgba(94, 234, 212, 0.4);
  background: rgba(12, 18, 26, 0.94);
  transform: translateY(-2px);
}
.card:hover::after { opacity: 1; }

.card-icon {
  width: 36px; height: 36px;
  flex: none;
  border-radius: 9px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(94, 234, 212, 0.22);
  background: rgba(94, 234, 212, 0.06);
  color: var(--accent);
}
.card-icon svg { width: 17px; height: 17px; }
.card-body { min-width: 0; flex: 1; }
.card-body strong { display: block; font-size: 14px; font-weight: 600; letter-spacing: 0.01em; }
.card-body small { display: block; margin-top: 4px; font-size: 12px; color: var(--muted); line-height: 1.55; }
.card-body code {
  display: block;
  margin-top: 7px;
  font-family: var(--mono);
  font-size: 10px;
  color: var(--dim);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.card-arrow {
  flex: none;
  color: var(--dim);
  transition: color 0.24s ease, transform 0.24s ease;
  align-self: center;
}
.card:hover .card-arrow { color: var(--accent); transform: translate(2px, -2px); }
.card-arrow svg { width: 14px; height: 14px; display: block; }

.board-empty { margin: 40px 0 0; text-align: center; color: var(--dim); font-size: 13.5px; }

/* ---------- responsive ---------- */
@media (max-width: 860px) {
  .wrap { padding: 0 18px; }
  .header-tag, .session { display: none; }
  .nav-main { padding-top: 30px; }
  .board-head { flex-direction: column; align-items: flex-start; gap: 18px; }
  .board-tools { width: 100%; }
  .search { width: 100%; }
  .card-grid { grid-template-columns: 1fr; }
  .login-card { padding: 30px 22px 26px; }
}