:root {
  --bg-color: #0d1117;
  --panel-bg: #161b22;
  --card-bg: #1c2128;
  --border-color: #30363d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  
  --diff-add-bg: rgba(46, 160, 67, 0.15);
  --diff-add-text: #3fb950;
  --diff-add-highlight: rgba(46, 160, 67, 0.4);
  
  --diff-rem-bg: rgba(248, 81, 73, 0.15);
  --diff-rem-text: #f85149;
  --diff-rem-highlight: rgba(248, 81, 73, 0.4);

  --font-sans: 'Inter', -apple-system, sans-serif;
  --font-mono: 'Fira Code', ui-monospace, SFMono-Regular, monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
}

.code-font { font-family: var(--font-mono); font-size: 14px; }

header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  border-bottom: 1px solid var(--border-color);
  padding: 1.5rem 2rem;
}

.header-left h1 { font-size: 1.5rem; font-weight: 600; margin-top: 0.5rem; }
.header-right p { color: var(--text-secondary); font-size: 0.875rem; }

.back-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s;
  display: inline-block;
  margin-bottom: 0.5rem;
}
.back-link:hover { color: var(--accent-color); }

.main-content {
  padding: 1.5rem 2rem;
  max-width: 1600px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  height: calc(100vh - 100px);
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
}

button {
  cursor: pointer;
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 6px;
  padding: 0.5rem 1.25rem;
  transition: 0.2s;
}

.primary-btn { background-color: #238636; color: #fff; border: 1px solid rgba(240, 246, 252, 0.1); }
.primary-btn:hover { background-color: #2ea043; }
.secondary-btn { background-color: var(--panel-bg); color: var(--text-primary); border: 1px solid var(--border-color); }
.secondary-btn:hover { background-color: #30363d; border-color: #8b949e; }
.secondary-btn.danger { color: #f85149; }
.secondary-btn.danger:hover { background-color: rgba(248, 81, 73, 0.1); border-color: #f85149; }

.controls-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.view-toggles { display: flex; gap: 0.5rem; }
.toggle-btn { background: transparent; border: 1px solid transparent; color: var(--text-secondary); }
.toggle-btn:hover { color: var(--text-primary); }
.toggle-btn.active { background: var(--panel-bg); border-color: var(--border-color); color: var(--text-primary); }

.actions { display: flex; gap: 0.5rem; }

/* Input Layout */
.input-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  flex-grow: 1;
}

.pane { display: flex; flex-direction: column; }
.pane-header { margin-bottom: 0.75rem; }
.pane-header h2 { font-size: 1rem; color: var(--text-secondary); font-weight: 500;}

.diff-input {
  flex-grow: 1;
  width: 100%;
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  padding: 1rem;
  resize: none;
  outline: none;
  line-height: 1.5;
  white-space: pre;
  overflow-wrap: normal;
  overflow-x: auto;
}
.diff-input:focus { border-color: var(--accent-color); }

/* Output Layout */
.output-section {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.output-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}
.output-header h2 { font-size: 1.125rem;}

.legend { display: flex; gap: 1rem; }
.legend-item { font-family: var(--font-mono); font-size: 0.875rem; padding: 0.2rem 0.5rem; border-radius: 4px; }
.bg-added { background-color: var(--diff-add-bg); color: var(--diff-add-text); }
.bg-removed { background-color: var(--diff-rem-bg); color: var(--diff-rem-text); }

.diff-container {
  flex-grow: 1;
  overflow-y: auto;
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
}

/* Diff Render Styles */
.diff-table {
  width: 100%;
  border-collapse: collapse;
  table-layout: fixed;
}

.diff-row { display: flex; width: 100%; }
.diff-row:hover { background-color: rgba(255,255,255,0.02); }

.diff-num {
  width: 40px;
  min-width: 40px;
  padding: 0 0.5rem;
  text-align: right;
  color: var(--text-secondary);
  user-select: none;
  border-right: 1px solid var(--border-color);
  opacity: 0.5;
}

.diff-text {
  flex-grow: 1;
  padding: 0 1rem;
  white-space: pre-wrap;
  word-break: break-all;
  min-height: 1.5em; /* force empty lines to render */
}

/* Unified View Specifics */
.diff-row.added { background-color: var(--diff-add-bg); }
.diff-row.removed { background-color: var(--diff-rem-bg); }
.diff-row.added .diff-text { color: var(--text-primary); }
.diff-row.removed .diff-text { color: var(--text-primary); }

.diff-text .char-add { background-color: var(--diff-add-highlight); }
.diff-text .char-rm { background-color: var(--diff-rem-highlight); }

/* Split View Specifics */
.split-table {
  display: flex;
  width: 100%;
}
.split-side {
  width: 50%;
  display: flex;
  flex-direction: column;
}
.split-side.left { border-right: 1px solid var(--border-color); }

.split-line {
  display: flex;
  width: 100%;
}
.split-line.added { background-color: var(--diff-add-bg); }
.split-line.removed { background-color: var(--diff-rem-bg); }
.split-line.empty { background-color: rgba(0,0,0,0.2); }