:root{color-scheme:light;--bg: #f5f8ff;--panel: #ffffff;--ink: #162028;--muted: #687580;--line: #dbe5f4;--accent: #2563eb;--accent-strong: #1d4ed8;--danger: #a53b3b}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Microsoft YaHei,sans-serif}button,select{font:inherit}button{min-height:38px;border:1px solid var(--line);border-radius:6px;background:#fff;color:var(--ink);cursor:pointer;transition:border-color .16s ease,background .16s ease,color .16s ease}button:hover{border-color:var(--accent)}select{width:100%;min-height:36px;margin-top:6px;padding:0 10px;border:1px solid var(--line);border-radius:6px;background:#fff}.editor-shell{min-height:100vh;padding:24px}.topbar{display:flex;align-items:center;justify-content:space-between;gap:20px;max-width:1280px;margin:0 auto 18px}.eyebrow,.panel-label{margin:0;color:var(--accent-strong);font-size:12px;font-weight:800;letter-spacing:.08em;text-transform:uppercase}.topbar h1{margin:6px 0 0;font-size:30px;line-height:1.1}.topbar-status{min-width:150px;padding:12px 14px;border:1px solid var(--line);border-radius:8px;background:#ffffffb8;box-shadow:0 18px 46px #2563eb14;text-align:right}.topbar-status span{display:block;color:var(--muted);font-size:12px}.topbar-status strong{display:block;margin-top:2px}.workspace{display:grid;grid-template-columns:270px minmax(0,1fr);gap:18px;max-width:1280px;margin:0 auto}.tool-panel,.document-area,.html-output{border:1px solid var(--line);border-radius:8px;background:var(--panel);box-shadow:0 22px 60px #2563eb12}.tool-panel{display:grid;align-content:start;gap:16px;padding:16px}.panel-group{display:grid;gap:8px}.button-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.icon-button{min-width:0;font-weight:800}.icon-button.active,.primary-action{border-color:var(--accent);background:var(--accent);color:#fff}.danger-action{color:var(--danger)}.document-area{min-height:680px;padding:24px;overflow:auto}.paper{width:min(100%,860px);min-height:620px;margin:0 auto;padding:52px 58px;border:1px solid #e5eaef;border-radius:6px;background:#fff;box-shadow:0 18px 50px #2563eb14;outline:none;font-family:var(--editor-font-family, system-ui);font-size:var(--editor-font-size, 16px);line-height:1.75}.paper h1,.paper h2,.paper h3{line-height:1.25}.paper blockquote{margin-left:0;padding-left:16px;border-left:4px solid var(--accent);color:#42505a}.paper img{max-width:100%;border-radius:6px}.html-output{display:grid;grid-template-columns:220px minmax(0,1fr);gap:16px;max-width:1280px;margin:18px auto 0;padding:16px}.html-output p{margin:8px 0 0;color:var(--muted);font-size:14px}.html-output pre{max-height:240px;margin:0;padding:14px;overflow:auto;border:1px solid var(--line);border-radius:6px;background:#f8fbff;font-size:13px}@media(max-width:860px){.editor-shell{padding:14px}.topbar,.workspace,.html-output{grid-template-columns:1fr}.topbar{align-items:stretch;flex-direction:column}.topbar-status{text-align:left}.document-area{min-height:520px;padding:12px}.paper{min-height:480px;padding:28px 22px}}