:root{--bg-primary: #1a1a2e;--bg-secondary: #16213e;--bg-tertiary: #0f3460;--text-primary: #eaeaea;--text-secondary: #a0a0a0;--accent: #f0a500;--success: #4ecca3;--error: #ff6b6b}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:var(--bg-primary);color:var(--text-primary);min-height:100vh}a{color:var(--accent);text-decoration:none}button{background:var(--accent);color:var(--bg-primary);border:none;padding:.75rem 1.5rem;border-radius:8px;cursor:pointer;font-size:1rem;font-weight:600;transition:opacity .2s}button:hover{opacity:.9}button:disabled{opacity:.5;cursor:not-allowed}input{width:100%;padding:.75rem;border:1px solid var(--bg-tertiary);border-radius:8px;background:var(--bg-secondary);color:var(--text-primary);font-size:1rem;margin-bottom:1rem}input:focus{outline:none;border-color:var(--accent)}.auth-container{min-height:100vh;display:flex;align-items:center;justify-content:center}.auth-card{background:var(--bg-secondary);padding:2rem;border-radius:12px;width:100%;max-width:400px}.auth-card h1{text-align:center;margin-bottom:1.5rem;color:var(--accent)}.auth-card form{display:flex;flex-direction:column}.auth-card button{margin-top:1rem}.auth-card p{text-align:center;margin-top:1rem;color:var(--text-secondary)}.error{background:var(--error);color:#fff;padding:.75rem;border-radius:8px;margin-bottom:1rem;text-align:center}.home-container{display:flex;height:100vh}.sidebar{width:280px;background:var(--bg-secondary);display:flex;flex-direction:column;border-right:1px solid var(--bg-tertiary)}.sidebar-header{padding:1rem;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--bg-tertiary)}.sidebar-header h2{font-size:1.2rem;color:var(--accent)}.new-chat-btn{padding:.5rem 1rem;font-size:.9rem}.session-list{flex:1;overflow-y:auto}.session-item{padding:1rem;cursor:pointer;border-bottom:1px solid var(--bg-tertiary);transition:background .2s}.session-item:hover{background:var(--bg-tertiary)}.session-item.active{background:var(--bg-tertiary);border-left:3px solid var(--accent)}.session-title-wrapper{display:flex;justify-content:space-between;align-items:center}.session-title{flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.edit-btn{background:transparent;color:var(--text-secondary);padding:.25rem .5rem;font-size:.8rem;opacity:0;transition:opacity .2s}.session-item:hover .edit-btn{opacity:1}.edit-btn:hover{color:var(--accent)}.session-edit{display:flex;flex-direction:column;gap:.5rem}.session-edit input{margin-bottom:0;padding:.5rem;font-size:.9rem}.session-edit-actions{display:flex;gap:.5rem}.session-edit-actions button{flex:1;padding:.4rem .75rem;font-size:.8rem}.sidebar-footer{padding:1rem;border-top:1px solid var(--bg-tertiary);display:flex;flex-direction:column;gap:.5rem}.sidebar-footer button{background:transparent;color:var(--text-secondary);text-align:left;padding:.5rem}.sidebar-footer button:hover{color:var(--text-primary)}.chat-panel{flex:1;display:flex;flex-direction:column}.messages{flex:1;overflow-y:auto;padding:1rem;display:flex;flex-direction:column;gap:1rem}.message{max-width:70%;padding:1rem;border-radius:12px}.message.user{align-self:flex-end;background:var(--accent);color:var(--bg-primary)}.message.assistant{align-self:flex-start;background:var(--bg-secondary)}.message-content{white-space:pre-wrap;word-break:break-word}.chat-input{padding:1rem;display:flex;gap:1rem;border-top:1px solid var(--bg-tertiary);background:var(--bg-secondary)}.chat-input input{flex:1;margin-bottom:0}.settings-container{max-width:600px;margin:0 auto;padding:2rem}.settings-container h1{margin-bottom:2rem;color:var(--accent)}.settings-card{background:var(--bg-secondary);padding:2rem;border-radius:12px}.settings-card h2{margin-bottom:1rem}.settings-card form{display:flex;flex-direction:column}.settings-card button{margin-top:1rem}.current-keys{background:var(--bg-tertiary);padding:.75rem;border-radius:8px;margin-bottom:1rem;font-size:.9rem}.delete-btn{background:var(--error);margin-top:1rem}.history-container{max-width:900px;margin:0 auto;padding:2rem}.history-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem}.history-header h1{color:var(--accent)}.back-link{color:var(--text-secondary)}.summary-card{background:var(--bg-secondary);padding:1.5rem;border-radius:12px;margin-bottom:2rem}.summary-card h3{color:var(--text-secondary);margin-bottom:.5rem}.total-amount{font-size:2rem;font-weight:700;color:var(--success)}.history-table{background:var(--bg-secondary);border-radius:12px;overflow:hidden}.history-table table{width:100%;border-collapse:collapse}.history-table th,.history-table td{padding:1rem;text-align:left}.history-table th{background:var(--bg-tertiary);color:var(--text-secondary);font-weight:600}.history-table tr{border-bottom:1px solid var(--bg-tertiary)}.history-table tr:last-child{border-bottom:none}.no-data{text-align:center;padding:2rem;color:var(--text-secondary)}