:root {
  --bg: #0b1020;
  --card: rgba(255,255,255,0.08);
  --card-border: rgba(255,255,255,0.12);
  --text: #e9eefc;
  --muted: rgba(233,238,252,0.72);
  --btn: rgba(255,255,255,0.10);
  --btn-hover: rgba(255,255,255,0.16);
  --accent: #7c5cff;
  --danger: #ff5c7a;
  --shadow: 0 18px 50px rgba(0,0,0,0.45);
  --radius: 16px;
  --radius-sm: 12px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
}

* { box-sizing: border-box; }
html, body { height: 100%; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--text);
  background:
    radial-gradient(900px 450px at 80% -10%, rgba(124,92,255,0.35), transparent 70%),
    radial-gradient(700px 380px at 10% 0%, rgba(255,92,122,0.20), transparent 70%),
    radial-gradient(900px 600px at 50% 120%, rgba(92,255,192,0.10), transparent 60%),
    var(--bg);
  display: grid;
  place-items: center;
  padding: 24px;
}

.shell {
  width: min(980px, 100%);
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 24px;
  align-items: start;
}

@media (max-width: 860px) {
  .shell { grid-template-columns: 1fr; }
}

header {
  padding: 24px;
  border-radius: var(--radius);
  background: var(--card);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

h1 {
  margin: 0 0 10px;
  font-size: clamp(26px, 4vw, 40px);
  letter-spacing: -0.02em;
}

p {
  margin: 0;
  color: var(--muted);
  line-height: 1.55;
  font-size: 15px;
}

.tips {
  margin-top: 16px;
  display: grid;
  gap: 10px;
  color: var(--muted);
  font-size: 14px;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--card-border);
  background: rgba(0,0,0,0.15);
  padding: 8px 12px;
  border-radius: 999px;
  width: fit-content;
  font-family: var(--mono);
  font-size: 12px;
  color: rgba(233,238,252,0.82);
}

.calc-card {
  border-radius: var(--radius);
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  overflow: hidden;
}

.display {
  padding: 18px 18px 12px;
  border-bottom: 1px solid var(--card-border);
  background: rgba(0,0,0,0.16);
}

.display .history {
  min-height: 18px;
  font-family: var(--mono);
  font-size: 12px;
  color: rgba(233,238,252,0.60);
  text-align: right;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.display .value {
  margin-top: 6px;
  font-family: var(--mono);
  font-size: 34px;
  letter-spacing: -0.02em;
  text-align: right;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 14px;
}

button {
  appearance: none;
  border: 1px solid var(--card-border);
  background: var(--btn);
  color: var(--text);
  border-radius: var(--radius-sm);
  padding: 14px 12px;
  font-size: 16px;
  font-family: var(--mono);
  cursor: pointer;
  transition: transform 0.05s ease, background 0.15s ease;
  user-select: none;
}

button:hover { background: var(--btn-hover); }
button:active { transform: translateY(1px); }
button:focus-visible { outline: 2px solid rgba(124,92,255,0.7); outline-offset: 2px; }

.op { background: rgba(124,92,255,0.20); border-color: rgba(124,92,255,0.40); }
.op:hover { background: rgba(124,92,255,0.28); }

.danger { background: rgba(255,92,122,0.18); border-color: rgba(255,92,122,0.38); }
.danger:hover { background: rgba(255,92,122,0.24); }

.equals {
  background: linear-gradient(135deg, rgba(124,92,255,0.55), rgba(124,92,255,0.20));
  border-color: rgba(124,92,255,0.60);
  grid-column: span 2;
  font-weight: 700;
}

.wide { grid-column: span 2; }

.footer-note {
  margin-top: 12px;
  padding: 0 14px 14px;
  color: rgba(233,238,252,0.55);
  font-size: 12px;
  text-align: center;
}

/* Category buttons (home page) */
.cat-card {
  border-radius: var(--radius);
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  overflow: hidden;
}

.cat-head {
  padding: 14px 16px 10px;
  border-bottom: 1px solid var(--card-border);
  background: rgba(0,0,0,0.10);
}

.cat-title {
  font-weight: 700;
  letter-spacing: -0.01em;
}

.cat-sub {
  margin-top: 4px;
  font-size: 12px;
  color: rgba(233,238,252,0.62);
}

.cat-grid {
  padding: 12px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  max-height: 270px;
  overflow: auto;
}

@media (max-width: 860px) {
  .cat-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    max-height: 220px;
  }
}

@media (max-width: 520px) {
  .cat-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.cat-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  border-radius: 999px;
  padding: 14px 16px;
  min-height: 48px;
  font-size: 12px;
  font-family: var(--mono);
  background: rgba(0,0,0,0.14);
  border: 1px solid var(--card-border);
  color: rgba(233,238,252,0.86);
  text-decoration: none;
  line-height: 1.1;
}

.cat-btn:hover { background: rgba(0,0,0,0.22); }
.cat-btn:focus-visible { outline: 2px solid rgba(124,92,255,0.7); outline-offset: 2px; }

/* Calculator lists (category pages) */
.calc-grid {
  margin-top: 14px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

@media (max-width: 860px) {
  .calc-grid { grid-template-columns: 1fr; }
}

.calc-tile {
  display: grid;
  gap: 6px;
  padding: 14px;
  border-radius: 14px;
  text-decoration: none;
  border: 1px solid var(--card-border);
  background: rgba(0,0,0,0.14);
  color: var(--text);
}

.calc-tile:hover { background: rgba(0,0,0,0.22); }
.calc-tile:focus-visible { outline: 2px solid rgba(124,92,255,0.7); outline-offset: 2px; }

.calc-name {
  font-weight: 700;
  letter-spacing: -0.01em;
}

.calc-desc {
  font-size: 13px;
  color: rgba(233,238,252,0.68);
  line-height: 1.35;
}

/* Shared page layout for secondary pages */
.page {
  width: min(980px, 100%);
  display: grid;
  gap: 18px;
}

.card {
  padding: 22px;
  border-radius: var(--radius);
  background: var(--card);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

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

.nav-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.nav-links a {
  color: rgba(233,238,252,0.82);
  text-decoration: none;
  border: 1px solid var(--card-border);
  padding: 8px 10px;
  border-radius: 999px;
  background: rgba(0,0,0,0.12);
  font-size: 12px;
  font-family: var(--mono);
}

.nav-links a:hover { background: rgba(0,0,0,0.20); }

.site-footer {
  margin-top: 22px;
  padding: 16px 18px;
  border-radius: var(--radius);
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--card-border);
  backdrop-filter: blur(10px);
}

.site-footer .links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
}

.site-footer a {
  color: rgba(233,238,252,0.82);
  text-decoration: none;
  font-size: 13px;
  border-bottom: 1px dotted rgba(233,238,252,0.35);
}

.site-footer a:hover { color: var(--text); border-bottom-color: rgba(233,238,252,0.65); }

.site-footer .copyright {
  margin-top: 10px;
  text-align: center;
  color: rgba(233,238,252,0.55);
  font-size: 12px;
}

.form {
  display: grid;
  gap: 12px;
  margin-top: 12px;
}

.input {
  display: grid;
  gap: 6px;
}

label {
  font-size: 13px;
  color: rgba(233,238,252,0.82);
}

input, textarea {
  width: 100%;
  padding: 12px 12px;
  border-radius: 12px;
  border: 1px solid var(--card-border);
  background: rgba(0,0,0,0.18);
  color: var(--text);
  font-family: var(--sans);
}

textarea { min-height: 120px; resize: vertical; }

.small {
  font-size: 12px;
  color: rgba(233,238,252,0.60);
}

.btn {
  width: fit-content;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid rgba(124,92,255,0.55);
  background: rgba(124,92,255,0.22);
  color: var(--text);
  cursor: pointer;
  font-family: var(--mono);
}

.btn:hover { background: rgba(124,92,255,0.30); }