feat: add styles for slider and color picker fields

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

styles.css

@@ -301,6 +301,97 @@
 }
 
 
+/* ==========================================================================
+   Slider
+   ========================================================================== */
+
+.ff-slider-wrapper {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+}
+
+.ff-slider {
+  flex: 1;
+  height: 6px;
+  -webkit-appearance: none;
+  appearance: none;
+  background: var(--background-modifier-border);
+  border-radius: 3px;
+  outline: none;
+  cursor: pointer;
+}
+
+.ff-slider::-webkit-slider-thumb {
+  -webkit-appearance: none;
+  width: 18px;
+  height: 18px;
+  border-radius: 50%;
+  background: var(--interactive-accent);
+  cursor: pointer;
+  transition: box-shadow 0.15s ease;
+}
+
+.ff-slider::-webkit-slider-thumb:hover {
+  box-shadow: 0 0 0 4px color-mix(in srgb, var(--interactive-accent) 20%, transparent);
+}
+
+.ff-slider::-moz-range-thumb {
+  width: 18px;
+  height: 18px;
+  border: none;
+  border-radius: 50%;
+  background: var(--interactive-accent);
+  cursor: pointer;
+}
+
+.ff-slider-value {
+  min-width: 36px;
+  text-align: right;
+  font-size: 0.85rem;
+  font-weight: 500;
+  color: var(--text-normal);
+  font-variant-numeric: tabular-nums;
+}
+
+
+/* ==========================================================================
+   Color Picker
+   ========================================================================== */
+
+.ff-color-wrapper {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+}
+
+.ff-color-input {
+  width: 40px;
+  height: 32px;
+  padding: 2px;
+  border: 1px solid var(--background-modifier-border);
+  border-radius: 4px;
+  background: var(--background-primary);
+  cursor: pointer;
+}
+
+.ff-color-input::-webkit-color-swatch-wrapper {
+  padding: 2px;
+}
+
+.ff-color-input::-webkit-color-swatch {
+  border: none;
+  border-radius: 2px;
+}
+
+.ff-color-hex {
+  font-size: 0.85rem;
+  font-family: var(--font-monospace);
+  color: var(--text-muted);
+  letter-spacing: 0.03em;
+}
+
+
 /* ==========================================================================
    Form Modal
    ========================================================================== */