:root { --main: #117c9a; --main-dark: #0c4d60; --bg: #f8fbff; }
      body { background: var(--bg); margin: 0; font-family: "Segoe UI", Arial, sans-serif; color: #234; }
      .container { max-width: 610px; margin: 38px auto 0 auto; background: #fff; border-radius: 18px; box-shadow: 0 4px 22px #117c9a33; padding: 28px 18px 22px 18px; }
      .logo { font-size: 1.25em; font-weight: bold; text-align: center; color: var(--main-dark); margin-bottom: 10px; }
      .desc { text-align: center; color: #19788a; margin-bottom: 16px; font-size: 1.03em; }
      .textarea-wrap { display: flex; gap: 12px; margin-bottom: 10px; flex-wrap: wrap; }
      textarea { flex: 1; min-width: 210px; min-height: 110px; border: 1.3px solid #afdbe6; border-radius: 8px; padding: 11px; font-size: 1.06em; background: #fafdff; font-family: "Fira Mono", "Menlo", monospace; resize: vertical; transition: border 0.18s; }
      textarea:focus { border-color: var(--main); }
      .label-row { display: flex; gap: 12px; justify-content: space-between; margin-bottom: 4px; font-size: 0.98em; }
      .label-row label { color: #127080; }
      .action-btn { background: var(--main); color: #fff; border: none; border-radius: 8px; padding: 11px 0; width: 100%; font-size: 1.13em; font-weight: bold; cursor: pointer; margin-top: 8px; margin-bottom: 13px; box-shadow: 0 2px 12px #117c9a28; transition: background 0.15s; }
      .action-btn:active { background: var(--main-dark); }
      .diff-result { min-height: 42px; background: #f7fcff; border: 1.1px solid #b2e0ee; border-radius: 7px; font-family: "Fira Mono", "Menlo", monospace; font-size: 1.06em; padding: 14px; white-space: pre-wrap; word-break: break-all; margin-bottom: 10px; }
      .footer { color: #789; text-align: center; font-size: 0.93em; margin-top: 15px; }
      .ins { background: #c6ffd8; color: #22843a; border-radius: 3px; padding: 1px 2px; }
      .del { background: #ffe3e3; color: #c13a3a; border-radius: 3px; padding: 1px 2px; }
      #backBtn { position: fixed; left: 50%; bottom: 32px; transform: translateX(-50%); background: #117c9a; color: #fff; font-weight: 700; border: none; border-radius: 2rem; padding: 0.58em 1.5em; box-shadow: 0 4px 16px #13d2b066; font-size: 1.09em; text-decoration: none; cursor: pointer; letter-spacing: 0.01em; transition: background 0.15s, transform 0.12s; z-index: 2000; }
      #backBtn:hover { background: #0c4d60; transform: translateX(-50%) scale(1.04); }
      @media (max-width: 700px) {
        .container { max-width: 99vw; padding: 11px 2vw 14px 2vw; }
        textarea { font-size: 1em; }
        #backBtn { bottom: 18px; font-size: 0.98em; padding: 0.48em 1em; }
      }
      section#faq { margin-top: 30px; }
      section#faq h2 { margin-bottom: 13px; color: #117c9a; font-size: 1.11em; text-align: center; }
      section#faq dt { font-weight: bold; margin-top: 8px; }
      section#faq dd { margin: 0 0 7px 0; font-size: 0.99em; color: #19788a; }