*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}:root{--color-bg: #f5f5f7;--color-surface: #ffffff;--color-surface-secondary: #f5f5f7;--color-border: #e5e5ea;--color-text-primary: #1d1d1f;--color-text-secondary: #6e6e73;--color-text-tertiary: #aeaeb2;--color-accent: #0071e3;--color-accent-hover: #0077ed;--color-accent-light: #e8f2ff;--color-error: #d93025;--color-error-light: #fce8e6;--color-warning: #92400e;--color-warning-light: #fef3c7;--color-success: #065f46;--color-success-light: #d1fae5;--color-user-bubble: #0071e3;--color-assistant-bubble: #f5f5f7;--radius-sm: 8px;--radius-md: 12px;--radius-lg: 16px;--font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;--font-mono: "SF Mono", "Fira Code", "Consolas", monospace;--shadow-sm: 0 1px 4px rgba(0, 0, 0, .06);--shadow-md: 0 2px 16px rgba(0, 0, 0, .08)}html,body{height:100%;font-family:var(--font-sans);background:var(--color-bg);color:var(--color-text-primary);font-size:15px;line-height:1.5;-webkit-font-smoothing:antialiased}#root,.app{height:100%;display:flex;flex-direction:column}.app-header{display:flex;align-items:center;gap:12px;padding:0 20px;height:52px;background:var(--color-surface);border-bottom:1px solid var(--color-border);flex-shrink:0;position:sticky;top:0;z-index:10}.app-header__logo{font-size:1rem;font-weight:700;color:var(--color-text-primary);letter-spacing:-.02em}.app-header__spacer{flex:1}.app-body{flex:1;display:flex;overflow:hidden}.sidebar{width:260px;flex-shrink:0;background:var(--color-surface);border-right:1px solid var(--color-border);display:flex;flex-direction:column;overflow:hidden}.sidebar__header{padding:14px 16px 10px;display:flex;align-items:center;gap:8px}.sidebar__title{font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--color-text-tertiary);flex:1}.sidebar__new-btn{display:flex;align-items:center;gap:6px;font-size:.8rem;font-weight:500;color:var(--color-accent);background:none;border:none;cursor:pointer;padding:4px 8px;border-radius:var(--radius-sm);transition:background .15s}.sidebar__new-btn:hover{background:var(--color-accent-light)}.sidebar__list{flex:1;overflow-y:auto;padding:4px 8px 16px}.sidebar__empty{padding:24px 16px;font-size:.85rem;color:var(--color-text-tertiary);text-align:center}.sidebar__loading{padding:16px;font-size:.85rem;color:var(--color-text-tertiary);text-align:center}.session-item{display:flex;align-items:center;gap:8px;padding:8px 10px;border-radius:var(--radius-sm);cursor:pointer;transition:background .12s;position:relative;min-width:0}.session-item:hover{background:var(--color-surface-secondary)}.session-item--active{background:var(--color-accent-light)}.session-item__title{flex:1;font-size:.85rem;color:var(--color-text-primary);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;min-width:0}.session-item--active .session-item__title{color:var(--color-accent);font-weight:500}.session-item__delete{flex-shrink:0;opacity:0;background:none;border:none;cursor:pointer;padding:2px 4px;border-radius:4px;color:var(--color-text-tertiary);font-size:1rem;line-height:1;transition:opacity .12s,color .12s,background .12s}.session-item:hover .session-item__delete{opacity:1}.session-item__delete:hover{color:var(--color-error);background:var(--color-error-light)}.chat-main{flex:1;display:flex;flex-direction:column;overflow:hidden}.message-list{flex:1;overflow-y:auto;padding:24px 0;display:flex;flex-direction:column;gap:4px}.message-list__empty{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:8px;padding:48px 24px;color:var(--color-text-secondary)}.message-list__empty-icon{font-size:2.5rem;margin-bottom:8px}.message-list__empty-title{font-size:1.1rem;font-weight:600;color:var(--color-text-primary)}.message-list__empty-desc{font-size:.875rem;color:var(--color-text-secondary);text-align:center;max-width:300px}.message{display:flex;padding:2px 20px}.message--user{justify-content:flex-end}.message--assistant{justify-content:flex-start}.message__bubble{max-width:72%;padding:10px 14px;border-radius:var(--radius-md);font-size:.9rem;line-height:1.6;white-space:pre-wrap;word-break:break-word}.message--user .message__bubble{background:var(--color-user-bubble);color:#fff;border-bottom-right-radius:4px}.message--assistant .message__bubble{background:var(--color-assistant-bubble);color:var(--color-text-primary);border-bottom-left-radius:4px;border:1px solid var(--color-border)}.message__streaming-cursor{display:inline-block;width:2px;height:1em;background:var(--color-text-secondary);animation:blink 1s step-end infinite;margin-left:2px;vertical-align:text-bottom}@keyframes blink{0%,to{opacity:1}50%{opacity:0}}.chat-input-area{padding:16px 20px 20px;background:var(--color-surface);border-top:1px solid var(--color-border);flex-shrink:0}.chat-input-form{display:flex;gap:10px;align-items:flex-end;max-width:800px;margin:0 auto}.chat-input{flex:1;min-height:44px;max-height:160px;padding:10px 14px;font-size:.9rem;font-family:var(--font-sans);color:var(--color-text-primary);background:var(--color-surface-secondary);border:1px solid var(--color-border);border-radius:var(--radius-md);resize:none;outline:none;transition:border-color .15s,box-shadow .15s;line-height:1.5}.chat-input:focus{border-color:var(--color-accent);box-shadow:0 0 0 3px #0071e326}.chat-input:disabled{opacity:.6;cursor:not-allowed}.chat-input::placeholder{color:var(--color-text-tertiary)}.chat-send-btn{flex-shrink:0;width:44px;height:44px;border-radius:50%;background:var(--color-accent);color:#fff;border:none;cursor:pointer;display:flex;align-items:center;justify-content:center;transition:background .15s,transform .1s;font-size:1.1rem}.chat-send-btn:hover:not(:disabled){background:var(--color-accent-hover)}.chat-send-btn:active:not(:disabled){transform:scale(.95)}.chat-send-btn:disabled{opacity:.5;cursor:not-allowed}.chat-stop-btn{flex-shrink:0;padding:0 16px;height:44px;border-radius:var(--radius-md);background:var(--color-surface-secondary);color:var(--color-text-secondary);border:1px solid var(--color-border);cursor:pointer;font-size:.85rem;font-weight:500;transition:background .15s,color .15s}.chat-stop-btn:hover{background:var(--color-error-light);color:var(--color-error);border-color:var(--color-error)}.model-selector{display:flex;align-items:center;gap:6px}.model-selector__label{font-size:.8rem;color:var(--color-text-secondary)}.model-selector__select{font-size:.8rem;font-family:var(--font-sans);color:var(--color-text-primary);background:var(--color-surface-secondary);border:1px solid var(--color-border);border-radius:6px;padding:4px 8px;cursor:pointer;outline:none;transition:border-color .15s}.model-selector__select:focus{border-color:var(--color-accent)}.error-toast-container{position:fixed;top:60px;left:50%;transform:translate(-50%);z-index:100;display:flex;flex-direction:column;gap:8px;pointer-events:none;width:calc(100% - 40px);max-width:560px}.error-toast{display:flex;align-items:flex-start;gap:10px;background:var(--color-surface);border:1px solid var(--color-border);border-left:4px solid var(--color-error);border-radius:var(--radius-sm);padding:12px 14px;box-shadow:var(--shadow-md);pointer-events:auto;animation:toast-in .2s ease-out}.error-toast--warning{border-left-color:#f59e0b}.error-toast__icon{flex-shrink:0;font-size:1rem;margin-top:1px}.error-toast__body{flex:1;min-width:0}.error-toast__message{font-size:.875rem;color:var(--color-text-primary);line-height:1.4}.error-toast__retry{margin-top:6px;font-size:.8rem;font-weight:500;color:var(--color-accent);background:none;border:none;cursor:pointer;padding:0;text-decoration:underline}.error-toast__retry:hover{color:var(--color-accent-hover)}.error-toast__close{flex-shrink:0;background:none;border:none;cursor:pointer;color:var(--color-text-tertiary);font-size:1rem;padding:0;line-height:1;transition:color .12s}.error-toast__close:hover{color:var(--color-text-secondary)}@keyframes toast-in{0%{opacity:0;transform:translateY(-8px)}to{opacity:1;transform:translateY(0)}}.btn{display:inline-flex;align-items:center;gap:6px;padding:8px 16px;border-radius:var(--radius-sm);font-size:.875rem;font-weight:500;font-family:var(--font-sans);cursor:pointer;border:none;transition:background .15s,color .15s}.btn--primary{background:var(--color-accent);color:#fff}.btn--primary:hover{background:var(--color-accent-hover)}.btn--secondary{background:var(--color-surface-secondary);color:var(--color-text-secondary);border:1px solid var(--color-border)}.btn--secondary:hover{background:var(--color-border)}.sidebar__list::-webkit-scrollbar,.message-list::-webkit-scrollbar{width:4px}.sidebar__list::-webkit-scrollbar-track,.message-list::-webkit-scrollbar-track{background:transparent}.sidebar__list::-webkit-scrollbar-thumb,.message-list::-webkit-scrollbar-thumb{background:var(--color-border);border-radius:2px}@media (max-width: 640px){.sidebar{display:none}.message__bubble{max-width:88%}}