:root{color-scheme:light;font-family:Avenir Next,Trebuchet MS,sans-serif;--bg-soft: #f9f7f2;--bg-strong: #eff6ff;--ink: #1f2937;--ink-soft: #475569;--panel: #fffdf8;--line: #d8dfef;--brand: #0e7490;--brand-dark: #155e75;--highlight: #f97316}*{box-sizing:border-box}body{margin:0;min-height:100vh;color:var(--ink);background:radial-gradient(circle at 20% 18%,#dcfce7 0%,transparent 34%),radial-gradient(circle at 85% 10%,#dbeafe 0%,transparent 28%),linear-gradient(140deg,var(--bg-soft) 0%,var(--bg-strong) 100%)}.page{min-height:100vh;padding:28px;width:100%;display:flex;flex-direction:column;gap:20px}.site-header{display:flex;justify-content:space-between;align-items:center}.site-brand{display:grid;gap:2px}.site-logo{margin:0;font-weight:800;letter-spacing:.14em;text-transform:uppercase;color:var(--highlight);font-size:1.02rem}.site-tagline{margin:0;font-size:.78rem;color:var(--ink-soft);font-weight:600}.site-actions{display:flex;align-items:center;gap:12px}.auth-links{display:flex;align-items:center;gap:8px}.auth-btn{padding:7px 12px;border-radius:999px;font-size:.82rem;font-weight:700}.auth-btn-ghost{border:1px solid #bac8e2;background:#fff;color:var(--ink)}.auth-btn-ghost:hover{background:#f8fafc}.auth-btn-solid{border:1px solid transparent;background:var(--brand);color:#fff}.welcome-main{flex:1;display:grid;grid-template-rows:1fr auto;gap:24px}.home-header{display:grid;grid-template-columns:1.2fr 1fr;gap:28px;align-items:start;align-self:center}.brand h1{margin:4px 0 12px;font-size:clamp(2.1rem,4.2vw,3.2rem);line-height:1.05}.kicker{margin:0;font-size:.78rem;letter-spacing:.16em;text-transform:uppercase;color:var(--highlight);font-weight:700}.summary{margin:0;max-width:580px;color:var(--ink-soft);font-size:1.05rem}.prompt-launcher{background:#ffffffe0;border:1px solid var(--line);border-radius:18px;padding:16px;box-shadow:0 16px 32px #02061714}.prompt-launcher label{display:block;margin-bottom:8px;font-weight:700;font-size:.92rem}.prompt-launcher textarea{width:100%;resize:none;border-radius:12px;border:1px solid #c9d5ea;padding:11px 12px;font:inherit;color:var(--ink);background:#fff;min-height:104px}.prompt-launcher textarea:focus{outline:3px solid rgba(14,116,144,.16)}.prompt-launcher button{margin-top:10px;width:100%}.home-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;margin-top:0}.feature{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:18px}.feature h2{margin:0 0 8px;font-size:1.08rem}.feature p{margin:0;color:var(--ink-soft)}.site-footer{display:flex;justify-content:space-between;align-items:center;border-top:1px solid var(--line);padding-top:12px}.site-footer p{margin:0;color:var(--ink-soft);font-size:.84rem}.auth-modal-backdrop{position:fixed;top:0;right:0;bottom:0;left:0;background:#0f172a73;display:grid;place-items:center;z-index:1000;padding:16px}.auth-modal{width:min(480px,100%);background:#fff;border:1px solid var(--line);border-radius:16px;box-shadow:0 20px 40px #0f172a3d;padding:16px}.auth-modal-header{display:flex;justify-content:space-between;align-items:center;gap:12px}.auth-modal-header h2{margin:0;font-size:1.2rem}.auth-close-btn{padding:3px 9px;border-radius:8px;border:1px solid #cbd5e1;background:#fff;color:var(--ink);line-height:1}.auth-close-btn:hover{background:#f8fafc}.auth-modal-tabs{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;margin-top:12px}.auth-tab{border:1px solid #cbd5e1;border-radius:10px;background:#fff;color:var(--ink)}.auth-tab.active{border-color:var(--brand);background:#e0f2fe;color:#0c4a6e}.auth-form{margin-top:14px;display:grid;gap:12px}.google-auth-btn{margin-top:14px;width:100%;min-height:40px;display:inline-flex;align-items:center;justify-content:center;gap:10px;padding:9px 14px;background:#fff;color:#3c4043;border:1px solid #dadce0;border-radius:999px;font-family:Roboto,Helvetica Neue,Arial,sans-serif;font-size:.92rem;font-weight:500;letter-spacing:.01em;transition:box-shadow .16s ease,border-color .16s ease,background-color .16s ease}.google-auth-btn:hover{background:#fff;border-color:#c7c9cc;box-shadow:0 1px 2px #3c404333,0 1px 3px 1px #3c40431a}.google-auth-btn:focus-visible{outline:2px solid #1a73e8;outline-offset:2px}.google-auth-btn:disabled{cursor:not-allowed;opacity:.7;box-shadow:none}.google-auth-icon{width:18px;height:18px;display:inline-flex;align-items:center;justify-content:center;flex-shrink:0}.auth-separator{margin:12px 0 4px;text-align:center;color:#64748b;font-size:.82rem;text-transform:uppercase;letter-spacing:.08em}.auth-form label{display:grid;gap:6px;font-size:.9rem;font-weight:600;color:var(--ink)}.auth-form input{border:1px solid #cbd5e1;border-radius:10px;padding:10px 11px;font:inherit}.auth-form input:focus{outline:3px solid rgba(14,116,144,.15)}.auth-submit{margin-top:4px;width:100%}.auth-feedback{margin:0;border-radius:10px;padding:10px 12px;font-size:.88rem;line-height:1.4}.auth-feedback-error{background:#fef2f2;border:1px solid #fecaca;color:#991b1b}.auth-feedback-success{background:#ecfdf5;border:1px solid #bbf7d0;color:#166534}.row{display:grid;gap:6px;margin-bottom:12px}.label{font-size:.85rem;color:#525f70}code{display:inline-block;background:#f8f9fc;border:1px solid #dde4f3;border-radius:8px;padding:8px 10px;word-break:break-all}button{border:none;border-radius:11px;background:var(--brand);color:#fff;padding:10px 14px;font-weight:700;cursor:pointer}button:hover{background:var(--brand-dark)}.status{margin-top:12px;font-weight:600}.chat-page{min-height:100vh;display:grid;grid-template-columns:300px 1fr;gap:18px;padding:20px}.chat-page.sidebar-collapsed{grid-template-columns:82px 1fr}.chat-history,.chat-main{background:#fff;border:1px solid var(--line);border-radius:18px}.chat-history{padding:14px;display:flex;flex-direction:column;max-height:calc(100vh - 40px)}.chat-history.collapsed{padding:10px 8px}.sidebar-toggle{margin:0 0 10px;border:1px solid #dbe4f1;background:#f8fafc;color:#334155}.sidebar-toggle:hover{background:#e2e8f0}.history-head h2{margin:0;font-size:1.15rem}.history-head p{margin:3px 0 0;color:var(--ink-soft);font-size:.85rem}.new-chat{margin-top:12px}.history-list{margin-top:12px;display:flex;flex-direction:column;gap:10px;overflow-y:auto;overflow-x:hidden;flex:1;min-height:0;padding-right:2px}.history-collapsed-rail{display:flex;flex-direction:column;align-items:center;flex:1}.icon-action-btn{margin-top:6px;width:44px;height:44px;padding:0;border-radius:12px;border:1px solid #c7d2fe;background:#eef2ff;color:#1e3a8a;display:inline-flex;align-items:center;justify-content:center}.icon-action-btn:hover{background:#dbeafe}.history-item{text-align:left;background:#f8fafc;color:var(--ink);border:1px solid #e2e8f0;padding:12px;border-radius:12px;min-height:auto}.history-item.active{background:#ecfeff;border-color:#67e8f9}.history-item strong,.history-item span,.history-item small{display:block}.history-item span{margin-top:4px;font-weight:500;color:var(--ink-soft);font-size:.84rem}.history-item small{margin-top:6px;font-size:.74rem;color:#6b7280}.history-list::-webkit-scrollbar{width:8px}.history-list::-webkit-scrollbar-track{background:transparent}.history-list::-webkit-scrollbar-thumb{background:#cbd5e1;border-radius:999px}.history-list::-webkit-scrollbar-thumb:hover{background:#94a3b8}.chat-user-panel{margin-top:12px;position:relative}.chat-user-actions{display:grid;grid-template-columns:1fr 1fr;gap:8px}.collapsed-panel{margin-top:10px}.collapsed-actions{grid-template-columns:1fr}.user-name-btn{background:#e2e8f0;color:#1e293b;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.user-name-btn:hover{background:#cbd5e1}.user-logout-btn{background:#b91c1c}.user-logout-btn:hover{background:#991b1b}.icon-user-badge,.icon-logout-btn{width:44px;height:44px;padding:0;margin:0 auto;border-radius:12px}.icon-user-badge{background:#e2e8f0;color:#1e293b}.icon-user-badge:hover{background:#cbd5e1}.icon-logout-btn{background:#b91c1c;color:#fff}.icon-logout-btn:hover{background:#991b1b}.profile-submenu{position:absolute;bottom:calc(100% + 8px);left:0;right:0;border:1px solid #dbe4f1;border-radius:12px;background:#fff;box-shadow:0 10px 24px #0f172a2e;padding:8px;display:grid;gap:6px;z-index:4}.collapsed-submenu{left:calc(100% + 8px);right:auto;bottom:0;min-width:220px}.profile-submenu-item{text-align:left;border:1px solid #e2e8f0;background:#fff;color:#334155;font-weight:600}.chat-main{padding:18px;display:grid;grid-template-rows:auto 1fr auto;max-height:calc(100vh - 40px)}.chat-header h1{margin:0 0 6px;font-size:1.4rem}.chat-header p{margin:0;color:var(--ink-soft)}.messages{margin-top:14px;overflow:auto;padding-right:4px}.message{border-radius:12px;padding:12px;margin-bottom:10px;max-width:85%}.message h3{margin:0 0 6px;font-size:.9rem}.message p{margin:0}.message a{color:#0c4a6e;font-weight:700}.message.student{background:#dbeafe;margin-left:auto}.message.assistant{background:#ecfccb}.empty-chat{margin:0;color:var(--ink-soft);background:#fff7ed;border:1px solid #fed7aa;border-radius:12px;padding:12px}.composer{margin-top:12px;display:grid;gap:10px}.composer textarea{width:100%;resize:vertical;min-height:100px;border-radius:12px;border:1px solid #c9d5ea;padding:11px 12px;font:inherit}.composer textarea:focus{outline:3px solid rgba(14,116,144,.16)}.practice-main{max-width:960px;margin:0 auto;display:grid;gap:14px}.practice-header h1{margin:0 0 4px}.practice-header p{margin:0 0 8px;color:var(--ink-soft)}.practice-header a{color:#0c4a6e;font-weight:700}.practice-filters,.practice-item{background:#fff;border:1px solid #dbe4f1;border-radius:12px;padding:12px}.practice-filters pre{margin:0;white-space:pre-wrap;word-break:break-word}.practice-list{display:grid;gap:10px}.practice-item h3{margin:0 0 8px}.practice-item ol{margin:0;padding-left:20px}@media (max-width: 980px){.page{padding:18px}.site-header{align-items:flex-start;flex-direction:column;gap:10px}.site-actions{width:100%;justify-content:space-between}.welcome-main{display:flex;justify-content:flex-start}.home-header,.home-grid{grid-template-columns:1fr}.site-footer{flex-direction:column;align-items:flex-start;gap:6px}.auth-modal{padding:14px}.chat-page,.chat-page.sidebar-collapsed{grid-template-columns:1fr}.chat-history.collapsed{padding:14px}.chat-history,.chat-main{max-height:none}}