:root {
  --bg: #f5f5f5;
  --text: #333;
  --text-light: #888;
  --border: #d0d0d0;
  --white: #fff;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --diff-added-text: #25d930;
  --diff-deleted-text: #d93025;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
  --radius: 10px;
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-size: 16px;
  --line-height: 1.6;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: var(--font-size);
}

body {
  font-family: var(--font);
  line-height: var(--line-height);
  color: var(--text);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

body.modal-open {
  overflow: hidden;
}

.header {
  text-align: center;
  padding: 32px 20px 16px;
}

.header__title {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.3px;
}

.header__accent {
  color: var(--primary);
}

.header__subtitle {
  margin-top: 4px;
  font-size: 14px;
  color: var(--text-light);
}

.main {
  flex: 1;
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px 40px;
}

.upload__areas {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 24px;
}

.upload-zone {
  display: flex;
  flex-direction: column;
}

.upload-zone__label {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-light);
  margin-bottom: 8px;
}

.upload-zone__drop {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 160px;
  padding: 32px 16px;
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  background: var(--white);
  cursor: pointer;
  text-align: center;
  transition: border-color 0.2s, background 0.2s;
}

.upload-zone__drop:hover {
  border-color: var(--primary);
}

.upload-zone__drop.drag-over {
  border-color: var(--primary);
  background: #eff6ff;
}

.upload-zone__input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
  z-index: 2;
}

.upload-zone__placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--text-light);
  pointer-events: none;
}

.upload-zone__icon {
  width: 40px;
  height: 40px;
  opacity: 0.4;
}

.upload-zone__file {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  pointer-events: none;
}

.upload-zone__filename {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  max-width: 100%;
  word-break: break-all;
}

.upload-zone__filesize {
  font-size: 13px;
  color: var(--text-light);
}

.upload-zone__clear {
  align-self: flex-end;
  margin-top: 8px;
  padding: 4px 14px;
  font-size: 13px;
  color: var(--text-light);
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
}

.upload-zone__clear:hover {
  color: var(--diff-deleted-text);
  border-color: var(--diff-deleted-text);
}

.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  padding: 10px 28px;
  font-size: 15px;
  font-weight: 600;
  border: 2px solid transparent;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
}

.btn--primary {
  background: var(--primary);
  color: var(--white);
  border-color: var(--primary);
}

.btn--primary:hover:not(:disabled) {
  background: var(--primary-hover);
  border-color: var(--primary-hover);
}

.btn--primary:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn--outline {
  background: var(--white);
  color: var(--text);
  border-color: var(--border);
}

.btn--outline:hover:not(:disabled) {
  border-color: var(--primary);
  color: var(--primary);
}

.btn--outline:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  border-color: var(--border);
  color: var(--text-light);
}

.upload__areas[hidden] {
  display: none;
}

.upload-summary[hidden] {
  display: none;
}

.upload-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 20px;
  margin-bottom: 24px;
  background: var(--white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  animation: fadeIn 0.3s;
}

.upload-summary__info {
  font-size: 14px;
  color: var(--text);
  line-height: 1.5;
}

.upload__actions {
  display: flex;
  justify-content: center;
  gap: 12px;
}

.loader {
  text-align: center;
  padding: 40px 20px;
  animation: fadeIn 0.3s;
}

.loader__spinner {
  width: 40px;
  height: 40px;
  margin: 0 auto 16px;
  border: 4px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

.loader__text {
  font-size: 14px;
  color: var(--text-light);
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.result {
  margin-top: 32px;
  animation: fadeIn 0.4s;
}

.result__toolbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 12px;
}

.result__title {
  font-size: 18px;
  font-weight: 600;
}

.result__actions {
  display: flex;
  gap: 10px;
}

.result__content {
  padding: 0;
  background: none;
}

.batch-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  padding: 12px;
  margin-bottom: 20px;
  background: var(--white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.batch-nav__filename {
  min-width: 120px;
  text-align: center;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
}

.batch-nav__select {
  padding: 6px 10px;
  font-size: 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--white);
  color: var(--text);
  cursor: pointer;
  max-width: 200px;
}

.batch-nav__select:focus {
  outline: none;
  border-color: var(--primary);
}

.result-tabs__header {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border);
  margin-bottom: 0;
}

.result-tabs__btn {
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-light);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  transition: all 0.2s;
}

.result-tabs__btn:hover {
  color: var(--text);
}

.result-tabs__btn--active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.result-tabs__body {
  display: none;
  padding: 20px 0;
}

.result-tabs__body--active {
  display: block;
}

.visual-diff {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}

.visual-diff__title {
  font-size: 14px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-light);
  text-align: center;
  margin-bottom: 12px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.visual-diff__pages {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.visual-page {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.visual-page__num {
  font-size: 12px;
  font-style: italic;
  color: var(--text-light);
  margin-bottom: 6px;
}

.visual-page__canvas-wrap {
  line-height: 0;
  overflow: hidden;
  border-radius: 4px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.visual-page__canvas-wrap canvas {
  display: block;
}

.pixel-diff__hint {
  text-align: center;
  font-size: 13px;
  font-style: italic;
  color: var(--text-light);
  margin-bottom: 20px;
}

.result__identical {
  text-align: center;
  padding: 40px;
  font-size: 18px;
  font-weight: 600;
  color: var(--diff-added-text);
}

.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: none;
  justify-content: center;
  align-items: center;
  background: rgba(0, 0, 0, 0.4);
}

.modal-overlay--active {
  display: flex;
  animation: fadeIn 0.2s;
}

.modal {
  position: relative;
  background: var(--white);
  border-radius: 12px;
  padding: 32px 40px;
  min-width: 280px;
  max-width: 90vw;
  text-align: center;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}

.modal__close {
  position: absolute;
  top: 8px;
  right: 12px;
  font-size: 24px;
  line-height: 1;
  color: var(--text-light);
  background: none;
  border: none;
  cursor: pointer;
}

.modal__close:hover {
  color: var(--text);
}

.modal__body {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.modal__logo {
  width: 96px;
  height: 96px;
  margin-bottom: 12px;
}

.modal__text {
  margin: 0;
  font-size: 14px;
  color: var(--text);
}

.notifications {
  position: fixed;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  pointer-events: none;
}

.notification {
  pointer-events: auto;
  padding: 12px 24px;
  max-width: 420px;
  font-size: 14px;
  font-weight: 500;
  text-align: center;
  background: var(--white);
  border-radius: 8px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  animation: slideDown 0.3s;
}

.notification--error {
  border-left: 4px solid var(--diff-deleted-text);
  color: var(--diff-deleted-text);
}

.notification--success {
  border-left: 4px solid var(--diff-added-text);
  color: var(--diff-added-text);
}

.notification--info {
  border-left: 4px solid var(--primary);
  color: var(--text);
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.notification.fade-out {
  animation: fadeOut 0.3s forwards;
}

@keyframes fadeOut {
  to {
    opacity: 0;
    transform: translateY(-12px);
  }
}

@media (max-width: 800px) {
  .upload__areas {
    grid-template-columns: 1fr;
  }

  .visual-diff {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .result__toolbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .result__actions {
    width: 100%;
  }

  .result__actions .btn {
    flex: 1;
  }

  .header__title {
    font-size: 22px;
  }

  .batch-nav {
    flex-wrap: wrap;
  }
}