diff --git a/main/animation.c b/main/animation.c
index 229bd4e..d544356 100644
--- a/main/animation.c
+++ b/main/animation.c
@@ -20,17 +20,22 @@ static animation_mode_t current_mode = ANIM_BLACK;
 static uint8_t global_hue = 0;
 static uint32_t frame_counter = 0;
 
-// Beat calculation helper (similar to FastLED beatsin16)
+// Beat calculation helper
 static int16_t beatsin16(uint8_t bpm, int16_t min_val, int16_t max_val)
 {
-    uint32_t ms = esp_timer_get_time() / 1000;
-    uint32_t beat = (ms * bpm * 256) / 60000;
-    uint8_t beat8 = (beat >> 8) & 0xFF;
+    // Use uint64_t to prevent overflow
+    uint64_t us = esp_timer_get_time(); // Microseconds
 
-    // Sin approximation
-    float angle = (beat8 / 255.0f) * 2.0f * M_PI;
+    // Calculate beat phase (0-65535 repeating at BPM rate)
+    // beats_per_minute → beats_per_microsecond = bpm / 60,000,000
+    uint64_t beat_phase = (us * (uint64_t)bpm * 65536ULL) / 60000000ULL;
+    uint16_t beat16 = (uint16_t)(beat_phase & 0xFFFF);
+
+    // Convert to angle (0 to 2π)
+    float angle = (beat16 / 65535.0f) * 2.0f * M_PI;
     float sin_val = sinf(angle);
 
+    // Map sin (-1 to +1) to output range (min_val to max_val)
     int16_t range = max_val - min_val;
     int16_t result = min_val + (int16_t)((sin_val + 1.0f) * range / 2.0f);
 
@@ -94,7 +99,7 @@ static void anim_white(void)
 
 static void anim_rainbow(void)
 {
-    // FastLED's built-in rainbow generator
+    // Rainbow generator
     uint16_t num_leds_a = led_get_num_leds_a();
     uint16_t num_leds_b = led_get_num_leds_b();
 
@@ -163,14 +168,14 @@ static void anim_sinelon(void)
     led_fade_to_black(20);
 
     uint16_t num_leds = led_get_num_leds_a() + led_get_num_leds_b();
-    int16_t pos = beatsin16(13, 0, num_leds - 1);
+    int16_t pos = beatsin16(13, 0, num_leds);
 
     hsv_t hsv = {global_hue, 255, 192};
     rgb_t color = led_hsv_to_rgb(hsv);
 
     if (pos < led_get_num_leds_a())
     {
-        led_add_pixel_a(pos, color);
+        led_add_pixel_a(led_get_num_leds_a() - pos - 1, color);
     }
     else
     {
@@ -223,9 +228,9 @@ static void anim_navigation(void)
     // Side red (last 3 LEDs of strip A)
     if (num_leds_a >= 3)
     {
-       led_set_pixel_a(num_leds_a - 1, red);
-       led_set_pixel_a(num_leds_a - 2, red);
-       led_set_pixel_a(num_leds_a - 3, red);
+        led_set_pixel_a(num_leds_a - 1, red);
+        led_set_pixel_a(num_leds_a - 2, red);
+        led_set_pixel_a(num_leds_a - 3, red);
     }
 
     // Side green (last 3 LEDs of strip B)
@@ -374,31 +379,31 @@ void animation_update(void)
         anim_white();
         break;
     case ANIM_RAINBOW:
-        //anim_rainbow();
+        // anim_rainbow();
         break;
     case ANIM_RAINBOW_GLITTER:
-        //anim_rainbow_glitter();
+        // anim_rainbow_glitter();
         break;
     case ANIM_CONFETTI:
-        //anim_confetti();
+        // anim_confetti();
         break;
     case ANIM_SINELON:
-        //anim_sinelon();
+        anim_sinelon();
         break;
     case ANIM_BPM:
-        //anim_bpm();
+        // anim_bpm();
         break;
     case ANIM_NAVIGATION:
         anim_navigation();
         break;
     case ANIM_CHASE:
-        //anim_chase();
+        // anim_chase();
         break;
     case ANIM_CHASE_RGB:
-        //anim_chase_rgb();
+        // anim_chase_rgb();
         break;
     case ANIM_RANDOM:
-        //anim_random();
+        // anim_random();
         break;
     default:
         anim_black();