*{box-sizing:border-box;}
html,body{margin:0;height:100%;font-family:'Segoe UI',system-ui,sans-serif;background:var(--bg-0);color:var(--text-0);}
#app-root{display:flex;flex-direction:column;height:100vh;}
#app-header{display:flex;align-items:center;justify-content:space-between;padding:0.75rem 1.5rem;
  background:var(--bg-1);border-bottom:1px solid var(--glass-border);}
.logo{font-size:1.1rem;margin:0;} .logo span{color:var(--accent);font-weight:300;margin-left:.4rem;}
#theme-toggle{cursor:pointer;font-size:1.4rem;padding:.3rem .6rem;border-radius:.6rem;}
#theme-toggle:hover{background:var(--glass);}
#screen-container{flex:1;overflow:auto;position:relative;}
.screen{width:100%;height:100%;padding:1rem;display:grid;}
.home-screen{grid-template-rows:auto 1fr;place-items:center;position:relative;overflow:hidden;}
.home-menu{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:.8rem;
  max-width:1100px;width:100%;z-index:2;padding:1rem;}
.build-screen{grid-template-columns:220px 1fr 260px;gap:.8rem;height:100%;}
#bike-canvas-wrap{position:relative;border-radius:1rem;overflow:hidden;background:var(--bg-2);}
#bike-canvas{width:100%;height:100%;display:block;}
#parts-tray,#inspector-panel{overflow-y:auto;padding:.8rem;border-radius:1rem;}
@media (max-width:900px){
  .home-screen{grid-template-columns:minmax(0,1fr);height:auto;min-height:100%;overflow:visible;}
  .home-menu{grid-template-columns:repeat(3,minmax(0,1fr));min-width:0;max-width:100%;}
  .home-menu button{min-width:0;overflow-wrap:anywhere;}
  .build-screen{
    grid-template-columns:1fr 1fr;
    grid-template-rows:auto auto;
    gap:.5rem;
    height:auto;
    min-height:100%;
  }
  #parts-tray{grid-column:1;grid-row:1;padding:.5rem;max-height:52vh;overflow-y:auto;}
  #bike-canvas-wrap{grid-column:2;grid-row:1;height:auto;min-height:0;max-height:52vh;overflow-y:auto;}
  #bike-canvas{height:auto;min-height:0;}
  #slot-drop-area{height:auto !important;overflow-y:visible;padding:.5rem !important;}
  #inspector-panel{grid-column:1 / span 2;grid-row:2;max-height:none;overflow-y:visible;padding:.6rem;}

  /* Compact parts & slots so two columns fit comfortably side by side */
  #parts-tray .part-card{padding:.45rem;gap:.35rem;margin-bottom:.35rem;border-width:1px;}
  #parts-tray .part-icon{font-size:1rem;}
  #parts-tray .part-name{font-size:.72rem;line-height:1.15;overflow-wrap:break-word;}
  #slot-drop-area h4{font-size:.85rem;margin:0 0 .4rem;}
  #slot-drop-area .dropzone{min-height:38px;padding:.35rem;margin-bottom:.3rem;font-size:.7rem;gap:.3rem;}
  #slot-drop-area .slot-label{overflow-wrap:break-word;}
}
@media (max-width:600px){
  .home-menu{grid-template-columns:repeat(2,minmax(0,1fr));padding:.5rem;}
}