/* ── Reset & tokens ─────────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f5f5f5;
  --surface: #ffffff;
  --surface2: #f0f0f0;
  --border: #d0d0d0;
  --text: #1a1a1a;
  --text-sub: #666666;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #eff6ff;
  --success: #16a34a;
  --error: #dc2626;
  --radius: 8px;
  --radius-sm: 4px;
  --shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,.07), 0 2px 4px rgba(0,0,0,.05);
  --font: system-ui, -apple-system, 'Segoe UI', sans-serif;
  --mono: 'Menlo', 'Consolas', 'Monaco', monospace;
}

[data-theme="dark"] {
  --bg: #0f0f0f;
  --surface: #1e1e1e;
  --surface2: #2a2a2a;
  --border: #3a3a3a;
  --text: #f0f0f0;
  --text-sub: #999999;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --accent-light: #1e3a5f;
  --success: #22c55e;
  --error: #f87171;
}

/* ── Base ───────────────────────────────────────────────────────────────────── */
html { font-size: 16px; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); }
a:hover { color: var(--accent-hover); }

.hidden { display: none !important; }

.text-sub { color: var(--text-sub); font-size: .85rem; }

/* ── Header ─────────────────────────────────────────────────────────────────── */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: .75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: .75rem;
}

.logo-icon { font-size: 2rem; line-height: 1; }

.logo h1 {
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.2;
}

.subtitle {
  font-size: .8rem;
  color: var(--text-sub);
  margin-top: .1rem;
}

.header-actions {
  display: flex;
  gap: .5rem;
}

.icon-btn {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  cursor: pointer;
  font-size: .875rem;
  font-weight: 600;
  padding: .35rem .75rem;
  transition: background .15s;
}
.icon-btn:hover { background: var(--border); }

/* ── Main ───────────────────────────────────────────────────────────────────── */
main {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem;
  flex: 1;
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* ── Toolbar / Tabs ──────────────────────────────────────────────────────────── */
.toolbar {
  display: flex;
  align-items: center;
  gap: .75rem;
  flex-wrap: wrap;
}

.tab-group {
  display: flex;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface2);
}

.tab-btn {
  background: transparent;
  border: none;
  border-right: 1px solid var(--border);
  color: var(--text-sub);
  cursor: pointer;
  font-size: .875rem;
  font-weight: 500;
  padding: .5rem 1rem;
  transition: background .15s, color .15s;
}
.tab-btn:last-child { border-right: none; }
.tab-btn:hover { background: var(--border); color: var(--text); }
.tab-btn.active {
  background: var(--accent);
  color: #fff;
}

/* ── Cipher description ─────────────────────────────────────────────────────── */
.cipher-desc {
  font-size: .875rem;
  color: var(--text-sub);
  padding: .5rem .75rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

/* ── Direction row ───────────────────────────────────────────────────────────── */
.dir-row {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.btn-group {
  display: flex;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.dir-btn {
  background: var(--surface2);
  border: none;
  border-right: 1px solid var(--border);
  color: var(--text-sub);
  cursor: pointer;
  font-size: .875rem;
  font-weight: 500;
  padding: .45rem 1.1rem;
  transition: background .15s, color .15s;
}
.dir-btn:last-child { border-right: none; }
.dir-btn:hover { background: var(--border); color: var(--text); }
.dir-btn.active { background: var(--accent); color: #fff; }

/* ── Param group ─────────────────────────────────────────────────────────────── */
.param-group {
  display: flex;
  align-items: center;
  gap: .6rem;
  flex-wrap: wrap;
}

.param-label {
  font-size: .875rem;
  font-weight: 500;
  color: var(--text-sub);
  white-space: nowrap;
}

.param-val {
  font-size: .875rem;
  font-weight: 700;
  min-width: 2ch;
  text-align: right;
}

input[type="range"] {
  accent-color: var(--accent);
  cursor: pointer;
  width: 140px;
}

.key-input {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: var(--mono);
  font-size: .875rem;
  padding: .35rem .65rem;
  width: 220px;
}
.key-input:focus {
  outline: 2px solid var(--accent);
  outline-offset: -1px;
}

/* ── I/O Panel ───────────────────────────────────────────────────────────────── */
.io-panel {
  display: flex;
  gap: .75rem;
  align-items: stretch;
}

.io-col {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: .35rem;
}

.io-label {
  font-size: .8rem;
  font-weight: 600;
  color: var(--text-sub);
  letter-spacing: .03em;
  text-transform: uppercase;
}

.io-textarea {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  flex: 1;
  font-family: var(--mono);
  font-size: .9rem;
  line-height: 1.55;
  min-height: 160px;
  padding: .75rem;
  resize: vertical;
  transition: border-color .15s;
  width: 100%;
}
.io-textarea:focus {
  border-color: var(--accent);
  outline: 2px solid var(--accent);
  outline-offset: -1px;
}
.io-textarea[readonly] {
  background: var(--surface2);
  cursor: default;
}

.io-sep {
  align-items: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.swap-btn {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-sub);
  cursor: pointer;
  font-size: .8rem;
  padding: .45rem .6rem;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  transition: background .15s, color .15s;
}
.swap-btn:hover { background: var(--border); color: var(--text); }

/* ── Action row ─────────────────────────────────────────────────────────────── */
.action-row {
  display: flex;
  gap: .65rem;
  flex-wrap: wrap;
}

.btn-secondary {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  cursor: pointer;
  font-size: .875rem;
  font-weight: 500;
  padding: .45rem 1rem;
  transition: background .15s, border-color .15s;
}
.btn-secondary:hover {
  background: var(--surface2);
  border-color: var(--accent);
  color: var(--accent);
}
.btn-secondary:disabled {
  cursor: default;
  opacity: .55;
}

/* ── Card ───────────────────────────────────────────────────────────────────── */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: .75rem;
}

.section-title {
  font-size: 1rem;
  font-weight: 700;
}

/* ── Brute Force Table ───────────────────────────────────────────────────────── */
.table-wrap {
  max-height: 400px;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.bf-table {
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: .8rem;
  width: 100%;
}
.bf-table th {
  background: var(--surface2);
  border-bottom: 1px solid var(--border);
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .05em;
  padding: .4rem .75rem;
  position: sticky;
  text-align: left;
  text-transform: uppercase;
  top: 0;
}
.bf-table td {
  border-bottom: 1px solid var(--border);
  padding: .35rem .75rem;
  vertical-align: top;
}
.bf-table tr:last-child td { border-bottom: none; }
.bf-table tr { cursor: pointer; transition: background .1s; }
.bf-table tr:hover { background: var(--surface2); }
.bf-table tr.best-row { background: var(--accent-light); font-weight: 600; }
[data-theme="dark"] .bf-table tr.best-row { background: var(--accent-light); }

.shift-num {
  color: var(--accent);
  font-weight: 700;
  white-space: nowrap;
  width: 4ch;
}
.result-text {
  word-break: break-all;
}

/* ── Frequency bars ─────────────────────────────────────────────────────────── */
.freq-meta {
  font-size: .875rem;
  color: var(--text-sub);
}

.freq-bars {
  display: grid;
  gap: .3rem;
}

.freq-row {
  display: grid;
  align-items: center;
  gap: .5rem;
  grid-template-columns: 1.5ch 1fr 6ch;
}

.freq-letter {
  font-family: var(--mono);
  font-size: .8rem;
  font-weight: 700;
  text-align: center;
  color: var(--accent);
}

.freq-bar-wrap {
  background: var(--surface2);
  border-radius: 2px;
  height: 10px;
  overflow: hidden;
}

.freq-bar {
  background: var(--accent);
  height: 100%;
  border-radius: 2px;
  transition: width .3s ease;
}

.freq-count {
  font-size: .75rem;
  text-align: right;
  color: var(--text-sub);
}
.freq-count small { color: var(--text-sub); }

/* ── Footer ─────────────────────────────────────────────────────────────────── */
footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  color: var(--text-sub);
  font-size: .8rem;
  padding: .75rem 1.5rem;
  text-align: center;
}

/* ── Responsive ──────────────────────────────────────────────────────────────── */
@media (max-width: 640px) {
  .io-panel {
    flex-direction: column;
  }
  .io-sep {
    flex-direction: row;
  }
  .swap-btn {
    writing-mode: horizontal-tb;
  }
  input[type="range"] {
    width: 100px;
  }
}