feat(intro): polish loading transition

src/index.css

@@ -873,72 +873,113 @@ canvas {
   position: fixed;
   inset: 0;
   z-index: 30;
-  display: grid;
-  place-items: center;
+  display: flex;
+  align-items: center;
+  justify-content: center;
   width: 100vw;
   height: 100vh;
-  background: #ffffff;
+  overflow: hidden;
+  background: #04070d;
   pointer-events: none;
   opacity: 1;
-  transition: opacity 640ms ease;
+  transition: opacity 500ms ease;
 }
 
 .scene-loading-overlay--ready {
   opacity: 0;
 }
 
-.scene-loading-overlay__content {
-  display: grid;
-  justify-items: center;
-  gap: 18px;
-  width: min(360px, calc(100vw - 48px));
-  padding: 28px;
-  background: rgba(255, 255, 255, 0.92);
-  border: 1px solid rgba(15, 23, 42, 0.08);
-  border-radius: 28px;
-  box-shadow: 0 24px 80px rgba(15, 23, 42, 0.12);
+.scene-loading-overlay__background,
+.scene-loading-overlay__shade {
+  position: absolute;
+  inset: 0;
 }
 
-.scene-loading-overlay strong {
-  color: #1e293b;
-  font-size: 15px;
-  font-weight: 600;
-  letter-spacing: 0.02em;
-  line-height: 1.45;
-  text-align: center;
+.scene-loading-overlay__background {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+}
+
+.scene-loading-overlay__shade {
+  background: rgba(4, 7, 13, 0.12);
+}
+
+.scene-loading-overlay__logo {
+  position: relative;
+  z-index: 1;
+  width: clamp(180px, 28vw, 320px);
+  max-height: min(38vh, 320px);
+  border-radius: 16px;
+  object-fit: cover;
+  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.28);
+}
+
+.scene-loading-overlay__footer {
+  position: absolute;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: 1;
+  display: grid;
+  gap: 12px;
+  padding: 0 clamp(18px, 4vw, 56px) clamp(22px, 5vh, 48px);
+}
+
+.scene-loading-overlay__meta {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 18px;
+  color: #ffffff;
+  font-family: "Nersans One", "Helvetica Neue", Helvetica, Arial, sans-serif;
+  font-size: clamp(16px, 2.3vw, 30px);
+  line-height: 1;
+  letter-spacing: 0.12em;
+  text-shadow: 0 2px 14px rgba(0, 0, 0, 0.45);
   text-transform: uppercase;
 }
 
+.scene-loading-overlay__label {
+  display: flex;
+  align-items: center;
+  gap: clamp(8px, 1.2vw, 14px);
+  min-width: 0;
+}
+
+.scene-loading-overlay__spinner {
+  flex: 0 0 auto;
+  width: clamp(18px, 2.2vw, 30px);
+  height: clamp(18px, 2.2vw, 30px);
+  color: #ffffff;
+  animation: scene-loading-spin 900ms linear infinite;
+}
+
+.scene-loading-overlay__meta strong {
+  color: inherit;
+  font: inherit;
+}
+
 .scene-loading-overlay__track {
   position: relative;
   overflow: hidden;
   width: 100%;
-  height: 18px;
-  background: #e2e8f0;
-  border-radius: 999px;
-  box-shadow: inset 0 0 0 1px rgba(15, 23, 42, 0.04);
+  height: clamp(7px, 1vw, 12px);
+  background: rgba(255, 255, 255, 0.22);
+  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.22);
 }
 
 .scene-loading-overlay__track span {
   display: block;
   height: 100%;
-  background: linear-gradient(90deg, #2563eb, #38bdf8);
-  border-radius: inherit;
+  background: #3b82f6;
   transition: width 180ms ease;
 }
 
-.scene-loading-overlay__track em {
-  position: absolute;
-  inset: 0;
-  display: grid;
-  place-items: center;
-  color: #ffffff;
-  font-size: 11px;
-  font-style: normal;
-  font-weight: 700;
-  letter-spacing: 0.04em;
-  line-height: 1;
-  text-shadow: 0 1px 4px rgba(15, 23, 42, 0.35);
+@keyframes scene-loading-spin {
+  to {
+    transform: rotate(360deg);
+  }
 }
 
 /* Subtitles */