:root {
  --page-padding: 24px;
  --main-padding: 28px;
  --main-max-width: 1100px;
  --body-font-size: 18px;
  --title-font-size: 1.75rem;
  --heading-font-size: 1.35rem;
  --label-font-size: 1rem;
  --button-font-size: 17px;
  --button-padding: 12px 20px;
  --lang-btn-font-size: 15px;
  --lang-btn-padding: 10px 14px;
  --file-btn-font-size: 15px;
  --file-btn-padding: 12px 18px;
  --file-label-font-size: 15px;
  --file-label-padding: 12px;
  --input-font-size: 16px;
  --input-padding: 10px 12px;
  --input-max-width: 420px;
  --control-label-font-size: 1rem;
  --color-swatch-size: 28px;
  --small-btn-size: 34px;
  --range-max-width: 180px;
  --control-group-min-width: 160px;
  --fieldset-padding: 12px;
  --preview-min-height: 360px;
  --footer-font-size: 0.95rem;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  font-size: var(--body-font-size);
  padding: var(--page-padding);
  background: #f7f7f7;
}

.tool-header {
  max-width: var(--main-max-width);
  margin: 0 auto 12px;
  padding: 0 4px;
}

.tool-home-link {
  color: #1a73e8;
  text-decoration: none;
  font-size: var(--label-font-size);
}

.tool-home-link:hover {
  text-decoration: underline;
}

main {
  max-width: var(--main-max-width);
  margin: 0 auto;
  background: #fff;
  padding: var(--main-padding);
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

h1, h2 {
  margin: 0 0 12px;
  line-height: 1.25;
}

#appTitle {
  font-size: var(--title-font-size);
}

#previewHeading {
  font-size: var(--heading-font-size);
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

#languageSwitcher {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
}

.lang-btn {
  padding: var(--lang-btn-padding);
  font-size: var(--lang-btn-font-size);
  border: 1px solid #ccc;
  border-radius: 6px;
  background: #fff;
  cursor: pointer;
}

.lang-btn.selected {
  background: #333;
  color: #fff;
  border-color: #333;
}

label {
  display: block;
  margin: 12px 0;
  font-size: var(--label-font-size);
}

input[type=file] {
  display: none;
}

input[type=text],
input[type=number],
select {
  font-size: var(--input-font-size);
  padding: var(--input-padding);
  border: 1px solid #ccc;
  border-radius: 4px;
  box-sizing: border-box;
}

input[type=text],
input[type=number] {
  width: 100%;
  max-width: var(--input-max-width);
}

.file-input-wrapper {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 8px;
}

.file-input-button {
  padding: var(--file-btn-padding);
  font-size: var(--file-btn-font-size);
  background: #fff;
  border: 1px solid #ccc;
  border-radius: 4px;
  cursor: pointer;
}

.file-input-button:hover {
  background: #f0f0f0;
}

.file-input-label {
  flex: 1;
  padding: var(--file-label-padding);
  background: #ffffcc;
  border: 1px solid #e0e0e0;
  border-radius: 4px;
  color: #333;
  font-size: var(--file-label-font-size);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

fieldset {
  border: 1px solid #ddd;
  padding: var(--fieldset-padding);
  font-size: var(--label-font-size);
}

button {
  padding: var(--button-padding);
  font-size: var(--button-font-size);
}

#submitButton {
  margin-top: 8px;
}

.control-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin: 12px 0;
  justify-content: flex-start;
}

.control-row .control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 0 1 var(--control-group-min-width);
  min-width: var(--control-group-min-width);
}

.control-group label {
  font-size: var(--control-label-font-size);
  white-space: nowrap;
  margin: 0;
}

.control-row input[type=range],
.control-row select {
  max-width: var(--range-max-width);
  width: 100%;
}

.control-row .control-with-buttons {
  gap: 6px;
}

.reset-group {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 6px;
  margin-left: auto;
  order: 99;
}

.reset-group button {
  min-width: 90px;
  border: 1px solid #ccc;
  border-radius: 6px;
  background: #fff;
  cursor: pointer;
  padding: 8px 12px;
  font-size: var(--file-btn-font-size);
}

.reset-group button:hover {
  background: #f0f0f0;
}

#previewHint {
  margin: 8px 0 0;
  color: #555;
  font-size: var(--control-label-font-size);
}

.color-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 8px 0;
  flex-wrap: wrap;
}

.color-swatch-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  justify-content: flex-end;
}

#colorLabel {
  white-space: nowrap;
  margin-bottom: 0;
}

.color-swatch {
  width: var(--color-swatch-size);
  height: var(--color-swatch-size);
  border-radius: 4px;
  border: 2px solid transparent;
  cursor: pointer;
}

.color-swatch.selected {
  border-color: #333;
}

#result {
  margin-top: 16px;
  font-size: var(--label-font-size);
}

#previewWrap {
  margin-top: 16px;
}

#previewContainer {
  position: relative;
  display: flex;
  justify-content: center;
  max-width: 100%;
  width: 100%;
  min-height: var(--preview-min-height);
  background: #222;
  border: 1px solid #ddd;
}

.preview-stage {
  position: relative;
  display: inline-block;
  line-height: 0;
  max-width: 100%;
}

.preview-hint {
  margin: 0 0 10px;
  color: #555;
  font-size: var(--control-label-font-size);
}

#previewCanvas {
  width: 100%;
  max-width: var(--main-max-width);
  border: none;
  display: block;
  background: #222;
}

.watermark-preview {
  position: absolute;
  pointer-events: auto;
  touch-action: none;
  cursor: grab;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
  user-select: none;
}

.watermark-preview.dragging {
  cursor: grabbing;
  outline: 2px dashed rgba(26, 115, 232, 0.8);
  outline-offset: 4px;
}

.watermark-preview .watermark-text {
  white-space: nowrap;
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK", Arial, sans-serif;
  line-height: 1;
  pointer-events: none;
}

.watermark-preview .watermark-image {
  display: block;
  max-width: none;
  pointer-events: none;
}

.site-footer {
  margin-top: 24px;
  text-align: center;
}

.site-footer a {
  color: #333;
  text-decoration: none;
  font-size: var(--footer-font-size);
}

.site-footer a:hover {
  text-decoration: underline;
}

.control-with-buttons {
  display: flex;
  align-items: center;
  gap: 8px;
}

.small-btn {
  width: var(--small-btn-size);
  height: var(--small-btn-size);
  font-size: var(--button-font-size);
  border: 1px solid #ccc;
  border-radius: 4px;
  background: #fff;
  cursor: pointer;
}

.small-btn:hover {
  background: #f0f0f0;
}

@media (max-width: 600px) {
  :root {
    --page-padding: 12px;
    --main-padding: 16px;
    --body-font-size: 16px;
    --title-font-size: 1.2rem;
    --heading-font-size: 1.05rem;
    --label-font-size: 0.95rem;
    --button-font-size: 16px;
    --button-padding: 12px 16px;
    --lang-btn-font-size: 12px;
    --lang-btn-padding: 8px 10px;
    --file-btn-font-size: 14px;
    --file-btn-padding: 11px 14px;
    --file-label-font-size: 14px;
    --file-label-padding: 11px;
    --input-font-size: 16px;
    --input-padding: 10px;
    --control-label-font-size: 0.9rem;
    --color-swatch-size: 32px;
    --small-btn-size: 40px;
    --range-max-width: 100%;
    --control-group-min-width: calc(50% - 8px);
    --fieldset-padding: 10px;
    --preview-min-height: 280px;
    --footer-font-size: 0.9rem;
  }

  main {
    display: flex;
    flex-direction: column;
  }

  .top-bar {
    order: 0;
  }

  #previewWrap {
    order: 1;
    position: sticky;
    top: 0;
    z-index: 10;
    margin: 0 -4px 12px;
    padding: 8px 4px 12px;
    background: #fff;
    border-bottom: 1px solid #ddd;
  }

  form {
    order: 2;
  }

  .site-footer {
    order: 3;
  }

  #previewHeading {
    margin: 0 0 8px;
  }

  #previewContainer {
    display: flex;
    justify-content: center;
    width: 100%;
    min-height: var(--preview-min-height);
    max-height: min(50vh, 420px);
    overflow: hidden;
    background: #222;
  }

  #previewCanvas {
    width: auto;
    max-width: 100%;
    max-height: min(50vh, 420px);
  }

  input[type=text],
  input[type=number] {
    max-width: 100%;
  }

  .control-row .control-group {
    flex: 1 1 calc(50% - 8px);
  }

  .reset-group {
    flex: 1 1 100%;
    align-items: stretch;
  }

  .reset-group button {
    width: 100%;
  }

  #submitButton {
    width: 100%;
  }
}

@media (min-width: 601px) {
  :root {
    --page-padding: 40px;
    --main-padding: 44px;
    --main-max-width: 1480px;
    --body-font-size: 26px;
    --title-font-size: 3rem;
    --heading-font-size: 2.1rem;
    --label-font-size: 1.3rem;
    --button-font-size: 24px;
    --button-padding: 18px 34px;
    --lang-btn-font-size: 20px;
    --lang-btn-padding: 14px 22px;
    --file-btn-font-size: 21px;
    --file-btn-padding: 16px 26px;
    --file-label-font-size: 21px;
    --file-label-padding: 16px;
    --input-font-size: 24px;
    --input-padding: 16px 18px;
    --input-max-width: 680px;
    --control-label-font-size: 1.25rem;
    --color-swatch-size: 42px;
    --small-btn-size: 52px;
    --range-max-width: 300px;
    --control-group-min-width: 240px;
    --fieldset-padding: 20px;
    --preview-min-height: 580px;
    --footer-font-size: 1.15rem;
  }

  .control-row {
    gap: 22px;
  }

  fieldset label {
    margin: 10px 20px 10px 0;
    display: inline-block;
  }
}

@media (min-width: 1200px) {
  :root {
    --main-max-width: 1600px;
    --body-font-size: 28px;
    --title-font-size: 3.4rem;
    --heading-font-size: 2.35rem;
    --button-font-size: 26px;
    --button-padding: 20px 38px;
    --input-font-size: 26px;
    --preview-min-height: 680px;
  }
}