Add WebGL book scene checkpoint

public/css/style.css

@@ -1926,3 +1926,195 @@ body:not([data-game-running="true"]) #start_prompt {
 .openai-setting {
     display: none; /* Hidden by default, shown when the relevant provider is selected */
 }
+
+body.webgl-mode {
+    background: #090705;
+    align-items: stretch;
+    justify-content: stretch;
+}
+
+#webgl_app {
+    position: fixed;
+    inset: 0;
+    overflow: hidden;
+    background: #090705;
+}
+
+#webgl_canvas {
+    position: absolute;
+    inset: 0;
+    width: 100%;
+    height: 100%;
+    display: block;
+}
+
+#top_menu {
+    position: fixed;
+    z-index: 50;
+    top: 0;
+    left: 0;
+    right: 0;
+    height: 38px;
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 18px;
+    box-sizing: border-box;
+    color: rgba(246, 231, 201, 0.94);
+    background: linear-gradient(180deg, rgba(13, 10, 7, 0.88), rgba(13, 10, 7, 0.46));
+    border-bottom: 1px solid rgba(246, 231, 201, 0.18);
+    font-size: 16px;
+    line-height: 1;
+}
+
+#top_menu_title {
+    overflow: hidden;
+    white-space: nowrap;
+    text-overflow: ellipsis;
+    min-width: 0;
+}
+
+#top_menu_controls {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    flex: 0 0 auto;
+}
+
+#top_menu_controls button,
+.modal-overview-row {
+    font-family: 'EB Garamond', serif;
+    font-size: 14px;
+    line-height: 1;
+    color: rgba(246, 231, 201, 0.92);
+    background: rgba(44, 28, 17, 0.72);
+    border: 1px solid rgba(246, 231, 201, 0.24);
+    border-radius: 4px;
+    padding: 6px 10px;
+    cursor: pointer;
+}
+
+#top_menu_controls button:hover,
+.modal-overview-row:hover {
+    background: rgba(87, 55, 31, 0.78);
+}
+
+#modal_overview {
+    position: fixed;
+    z-index: 45;
+    top: 52px;
+    right: 14px;
+    width: 164px;
+    color: rgba(246, 231, 201, 0.9);
+    background: rgba(12, 9, 7, 0.58);
+    border: 1px solid rgba(246, 231, 201, 0.18);
+    border-radius: 6px;
+    padding: 8px;
+    box-sizing: border-box;
+    backdrop-filter: blur(10px);
+}
+
+.modal-overview-title {
+    font-size: 13px;
+    line-height: 1;
+    margin: 0 0 8px;
+    color: rgba(246, 231, 201, 0.68);
+}
+
+#modal_overview_list {
+    display: grid;
+    gap: 6px;
+}
+
+.modal-overview-row {
+    display: flex;
+    justify-content: space-between;
+    width: 100%;
+    text-align: left;
+    padding: 6px 8px;
+}
+
+.modal-overview-row span:last-child {
+    color: rgba(246, 231, 201, 0.62);
+}
+
+body.webgl-mode #book {
+    position: fixed;
+    z-index: 20;
+    inset: 38px 0 0;
+    width: 100vw;
+    height: calc(100vh - 38px);
+    max-width: none;
+    max-height: none;
+    background: transparent;
+    pointer-events: none;
+    transform: none;
+    opacity: 0;
+}
+
+body.webgl-mode #page_left,
+body.webgl-mode #page_right {
+    pointer-events: none;
+    top: 10%;
+    bottom: auto;
+    height: 68vh;
+    max-height: 760px;
+    width: min(31vw, 500px);
+    background: #f2dfb8;
+    border: 0;
+    box-shadow: none;
+    opacity: 1;
+    mix-blend-mode: normal;
+}
+
+body.webgl-mode #page_left {
+    left: calc(50vw - min(33vw, 530px));
+    transform: none;
+    transform-origin: right center;
+}
+
+body.webgl-mode #page_right {
+    right: calc(50vw - min(33vw, 530px));
+    transform: none;
+    transform-origin: left center;
+}
+
+body.webgl-mode #lighting {
+    display: none;
+}
+
+@media (max-width: 780px) {
+    #modal_overview {
+        display: none;
+    }
+
+    #top_menu {
+        height: auto;
+        min-height: 42px;
+        gap: 8px;
+        padding: 6px 10px;
+    }
+
+    #top_menu_controls button {
+        padding: 6px 7px;
+    }
+
+    body.webgl-mode #book {
+        inset: 46px 0 0;
+    }
+
+    body.webgl-mode #page_left,
+    body.webgl-mode #page_right {
+        width: 44vw;
+        height: 66vh;
+        top: 12%;
+    }
+
+    body.webgl-mode #page_left {
+        left: 6vw;
+    }
+
+    body.webgl-mode #page_right {
+        right: 6vw;
+    }
+}