@media (max-width:1240px){.hero-stage{grid-template-columns:1fr}.hero-shell h1{max-width:11ch}}@media (max-width:1040px){body{padding:0;overflow:auto}.screen{width:100%}.auth-screen,.app-shell{min-height:100vh;border-radius:0}.auth-screen{height:auto;grid-template-columns:1fr;overflow:visible}.auth-card{border-left:0;border-top:1px solid var(--line)}.app-shell{grid-template-columns:320px minmax(0,1fr)}.main-panel{padding:18px}.message-stream{min-height:280px}.settings-grid{grid-template-columns:1fr}}@media (max-width:840px){.app-shell{grid-template-columns:1fr;grid-template-rows:auto minmax(0,1fr) auto;height:auto;min-height:100dvh}.mobile-topbar{position:sticky;top:0;z-index:4;display:flex}.main-panel{order:2;overflow:visible}.sidebar{order:3;border-right:0;border-bottom:0;border-top:1px solid var(--line);overflow:visible}.chat-list{max-height:260px}.chat-panel,.empty-state{min-height:60vh}.chat-header{flex-direction:column;align-items:flex-start}.chat-actions{justify-content:flex-start}.settings-panel{width:min(900px,100%)}.desktop-user-hub{display:none}}@media (max-width:680px){.lang-switcher{top:14px;right:14px;left:14px;justify-content:center}.auth-hero,.auth-card,.mobile-topbar,.sidebar,.main-panel,.settings-panel{padding-left:18px;padding-right:18px}.auth-hero{padding-top:72px}.hero-foot,.sidebar-stats{grid-template-columns:1fr;flex-direction:column}.toolbar-actions{width:100%;justify-content:stretch}.workspace-menu{top:calc(14px+env(safe-area-inset-top,0px));right:14px;left:14px;width:auto}.workspace-menu-actions{grid-template-columns:1fr}.toolbar-actions .ghost-btn{flex:1 1 120px}.profile-card,.avatar-upload-section{flex-direction:column;align-items:flex-start}.search-row{grid-template-columns:1fr}.chat-item-top{flex-wrap:wrap}.message-stream{padding:18px;min-height:46vh}.message-bubble{max-width:92%}.message-compose{grid-template-columns:auto minmax(0,1fr)}.send-btn{grid-column:1 / -1;width:100%}.modal{padding:0}.settings-panel{max-height:100vh;border-radius:0}}@media (max-width:520px){.auth-hero{gap:20px}.hero-shell h1{max-width:none;font-size:clamp(2.3rem,10vw,3.1rem)}.showcase-card{min-height:0}.sidebar-top,.mobile-topbar,.settings-header,.workspace-menu-head{flex-direction:column;align-items:flex-start}.toolbar-actions,.chat-actions{width:100%}.toolbar-actions .ghost-btn,.chat-actions .ghost-btn,.chat-actions .username-chip,.chat-actions .status-badge,.empty-card .ghost-btn,.workspace-menu-item,.mobile-user-hub{width:100%;justify-content:center}.mobile-user-hub{max-width:none}.sidebar-stats{grid-template-columns:1fr}.chat-header{padding:18px}.chat-title{width:100%}.chat-title-copy h2{font-size:1.08rem}.chat-title-copy p{font-size:0.84rem}.empty-card{padding:28px 22px}.empty-card h2{font-size:2rem}.settings-card{padding:18px}}