:root {
  --bg: #f2f2f2;
  --panel: #ffffff;
  --text: #151515;
  --muted: #4b4b4b;
  --border: rgba(0, 0, 0, 0.10);
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
  --focus: rgba(0, 120, 255, 0.35);
  --primary: #3f3f3f;
  --primary-2: #2e2e2e;

  --input-bg: #ffffff;
  --input-text: #151515;
  --placeholder: rgba(0,0,0,0.45);

  --btn-bg: #e9e9e9;
  --btn-hover: #dedede;

  --danger: #b00020;
  --ok: #0a7a2f;

  --radius: 14px;
  --radius-sm: 10px;
  --gap: 14px;

  --font: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
}

:root[data-theme="dark"] {
  --bg: #121212;
  --panel: #1a1a1a;
  --text: #ededed;
  --muted: #b8b8b8;
  --border: rgba(255, 255, 255, 0.12);
  --shadow: 0 12px 40px rgba(0, 0, 0, 0.35);
  --focus: rgba(120, 170, 255, 0.35);
  --primary: #ededed;
  --primary-2: #ffffff;

  --input-bg: #141414;
  --input-text: #ededed;
  --placeholder: rgba(255,255,255,0.55);

  --btn-bg: rgba(255,255,255,0.08);
  --btn-hover: rgba(255,255,255,0.12);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.4;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

.topbar {
  max-width: 1050px;
  margin: 22px auto 0;
  padding: 0 16px;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}

.logo{
  width: 70px;
  height: auto;
  border-radius: 90px;
  display: grid;
  place-items: center;
  display: block;
}

.container {
  max-width: 1050px;
  margin: 18px auto 30px;
  padding: 0 16px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
}

.card--secondary {
  margin-top: 14px;
}

.h1 {
  margin: 0 0 8px;
  font-size: 1.4rem;
  letter-spacing: 0.2px;
}
.h2 { margin: 0 0 10px; font-size: 1.15rem; }

.muted { color: var(--muted); }

.formula {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 0.98em;
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--gap);
  margin-top: 10px;
}

.field { grid-column: span 6; }
.field--wide { grid-column: span 12; }

label {
  display: block;
  margin-bottom: 6px;
  font-weight: 680;
  letter-spacing: 0.15px;
}

input[type="text"],
.select {
  width: 100%;
  padding: 11px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--input-bg);
  color: var(--input-text);
  outline: none;
}

input[type="text"]::placeholder {
  color: var(--placeholder);
}

input[type="text"]:focus,
.select:focus {
  box-shadow: 0 0 0 4px var(--focus);
}

.input-with-suffix {
  position: relative;
}
.input-with-suffix input {
  padding-right: 40px;
}
.suffix {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  font-weight: 650;
  pointer-events: none;
}

.hint {
  margin: 8px 0 0;
  font-size: 0.9rem;
  color: var(--muted);
}
.hint code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  background: rgba(127,127,127,0.12);
  padding: 1px 6px;
  border-radius: 999px;
}

.actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--btn-bg);
  color: var(--text);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.05s ease, background 0.15s ease;
}
.btn:hover { background: var(--btn-hover); }
.btn:active { transform: translateY(1px); }
.btn--ghost {
  background: transparent;
}
.btn--danger {
  border-color: rgba(176,0,32,0.35);
  color: var(--danger);
}

.result {
  padding: 14px;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--border);
  background: rgba(127,127,127,0.06);
}

.result__label {
  font-weight: 750;
  letter-spacing: 0.15px;
  margin-bottom: 6px;
}
.result__value {
  font-size: 1.6rem;
  font-weight: 850;
}
.result__meta {
  margin-top: 6px;
  font-size: 0.95rem;
}

.details {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  background: rgba(127,127,127,0.05);
}
details summary {
  cursor: pointer;
  font-weight: 700;
}
details summary::-webkit-details-marker { display: none; }
details summary::after { content: " ▾"; color: var(--muted); }
details[open] summary::after { content: " ▴"; }

.list {
  margin: 0;
  padding-left: 18px;
}
.list li { margin: 8px 0; }

.select {
  cursor: pointer;
}

.theme-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

@media (max-width: 860px) {
  .field { grid-column: span 12; }
  .topbar { align-items: stretch; flex-direction: column; }
}