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

body {
  font-family: "Poppins", sans-serif;
  background: #e0e0e0;
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  width: 100%;
  background-color: #111;
  padding: 20px;
  text-align: center;
}

header h1,
header h2 {
  color: #f0f0f0;
  font-size: 2rem;
  font-weight: bold;
  text-shadow: 2px 2px 8px #fff;
}

/* 入力エリア */
.container {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin: 2% auto 0;
  width: 80%;
  max-width: 1400px;
  padding: 20px;
  background: #e0e0e0;
  border-radius: 15px;
  box-shadow:
    10px 10px 15px rgba(0, 0, 0, 0.1),
    -10px -10px 15px rgba(255, 255, 255, 0.7);
}

.code-container {
  display: flex;
  flex-direction: column;
  width: 48%;
}

.code.drag-over {
  outline: 2px dashed #888;
  background: #e8e8e8;
}

.code-container label {
  font-weight: bold;
  margin-bottom: 5px;
  color: #555;
}

.code {
  width: 100%;
  height: 35vh;
  padding: 15px;
  font-family: monospace;
  font-size: 16px;
  white-space: pre-wrap;
  word-wrap: break-word;
  border: none;
  background: #f0f0f0;
  border-radius: 10px;
  box-shadow:
    inset 5px 5px 10px rgba(0, 0, 0, 0.1),
    inset -5px -5px 10px rgba(255, 255, 255, 0.7);
  overflow-y: auto;
}

/* ボタン */
.button-container {
  display: flex;
  gap: 10px;
  margin: 20px auto;
  width: 80%;
  max-width: 1400px;
}

button {
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
  background: #e0e0e0;
  border: none;
  border-radius: 10px;
  box-shadow:
    6px 6px 12px rgba(0, 0, 0, 0.1),
    -6px -6px 12px rgba(255, 255, 255, 0.7);
  transition: all 0.3s ease;
}

button:hover {
  background-color: #d1d1d1;
  box-shadow:
    4px 4px 8px rgba(0, 0, 0, 0.1),
    -4px -4px 8px rgba(255, 255, 255, 0.7);
}

button:active {
  box-shadow:
    inset 2px 2px 5px rgba(0, 0, 0, 0.2),
    inset -2px -2px 5px rgba(255, 255, 255, 0.7);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.option-label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 16px;
  cursor: pointer;
  color: #555;
  user-select: none;
}

.option-label input[type="checkbox"] {
  width: 16px;
  height: 16px;
  cursor: pointer;
}

/* サマリー */
.diff-summary {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  padding: 10px 20px;
  margin: 0 auto 12px;
  width: 80%;
  max-width: 1400px;
  background: #f0f0f0;
  border-radius: 10px;
  font-weight: bold;
  box-shadow:
    4px 4px 8px rgba(0, 0, 0, 0.08),
    -4px -4px 8px rgba(255, 255, 255, 0.6);
}

.summary-changed { color: #b45309; }
.summary-added   { color: #166534; }
.summary-removed { color: #991b1b; }

/* 並列diff */
.split-diff {
  display: flex;
  width: 80%;
  max-width: 1400px;
  margin: 0 auto 32px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow:
    6px 6px 12px rgba(0, 0, 0, 0.1),
    -6px -6px 12px rgba(255, 255, 255, 0.7);
}

.split-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

.split-panel:first-child {
  border-right: 2px solid #ccc;
}

.split-panel-header {
  padding: 10px 16px;
  font-family: "Poppins", sans-serif;
  font-weight: 600;
  font-size: 16px;
  background: #2a2a2a;
  color: #f0f0f0;
  flex-shrink: 0;
}

.split-panel-body {
  overflow-y: auto;
  max-height: 55vh;
  background: #fafafa;
  font-family: monospace;
  font-size: 16px;
}

/* 各行 */
.split-line {
  display: flex;
  align-items: baseline;
  min-height: 1.6em;
  border-bottom: 1px solid rgba(0, 0, 0, 0.04);
}

.split-line.line-unchanged   { background: #fafafa; }
.split-line.line-changed-old { background: #fff0f0; }
.split-line.line-changed-new { background: #f0fff4; }
.split-line.line-removed     { background: #ffe4e4; }
.split-line.line-added       { background: #dcfce7; }
.split-line.line-placeholder {
  background: #e8e8e8;
  background-image: repeating-linear-gradient(
    45deg,
    transparent,
    transparent 5px,
    rgba(0, 0, 0, 0.05) 5px,
    rgba(0, 0, 0, 0.05) 10px
  );
}

.ln {
  min-width: 3em;
  padding: 2px 8px;
  color: #ccc;
  user-select: none;
  text-align: right;
  flex-shrink: 0;
  border-right: 1px solid #e0e0e0;
  font-size: 16px;
}

.split-content {
  flex: 1;
  padding: 2px 12px;
  white-space: pre-wrap;
  word-wrap: break-word;
  min-width: 0;
}

/* 単語・文字レベルのハイライト */
.char-removed {
  background: #fca5a5;
  border-radius: 2px;
  padding: 0 1px;
}

.char-added {
  background: #6ee7b7;
  border-radius: 2px;
  padding: 0 1px;
}

.fullwidth-marker {
  background: #fbbf24;
  color: #78350f;
  border-radius: 3px;
  padding: 0 3px;
  font-weight: bold;
  outline: 1px solid #d97706;
}

/* 全角スペース警告 */
.fullwidth-warning {
  padding: 10px 20px;
  margin: 0 auto 8px;
  width: 80%;
  max-width: 1400px;
  background: #fff8e1;
  color: #7a5400;
  border-radius: 10px;
  font-size: 16px;
  font-weight: bold;
  box-shadow:
    4px 4px 8px rgba(0, 0, 0, 0.06),
    -4px -4px 8px rgba(255, 255, 255, 0.6);
}

/* 完全一致 */
.match-message {
  text-align: center;
  padding: 15px;
  margin: 0 auto 24px;
  width: 80%;
  max-width: 1400px;
  background: #dcfce7;
  color: #166534;
  border-radius: 10px;
  font-weight: bold;
}

footer {
  padding: 24px 20px;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: auto;
}

footer a {
  color: #555;
  text-decoration: none;
  margin: 0 12px;
}

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

footer .howto-link {
  display: inline-block;
  padding: 8px 20px;
  background: #2a2a2a;
  color: #f0f0f0;
  border-radius: 10px;
  font-weight: 600;
  text-decoration: none;
  box-shadow:
    6px 6px 12px rgba(0, 0, 0, 0.15),
    -6px -6px 12px rgba(255, 255, 255, 0.7);
  transition: all 0.3s ease;
}

footer .howto-link:hover {
  background: #444;
  text-decoration: none;
}

@media screen and (max-width: 768px) {
  .container      { flex-direction: column; gap: 20px; }
  .code-container { width: 100%; }
  .code           { height: 120px; }
  .button-container { width: 95%; margin-top: 20px; }
  button          { width: 100%; }
  .split-diff     { flex-direction: column; width: 95%; }
  .split-panel:first-child { border-right: none; border-bottom: 2px solid #ccc; }
  .diff-summary, .match-message { width: 95%; }
}