:root {
  --bg: #f8f6f3;
  --panel: #ffffff;
  --panel-2: #ffffff;
  --border: #ece7de;
  --border-soft: #f0ece3;
  --text: #2a2417;
  --muted: #8a8272;
  --muted-2: #b3ab9a;
  --accent: #ee9100;
  --accent-2: #eead00;
  --accent-soft: #ee910014;
  --accent-soft-strong: #ee910022;
  --rm-bg: #ff6b6b1f;
  --rm-text: #d94a4a;
  --add-bg: #22a55e1f;
  --add-text: #1c8a4d;
  --radius-lg: 22px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --shadow: 0 24px 60px -24px rgba(60, 45, 10, 0.18);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  background: var(--bg);
}

body {
  font-family: "Manrope", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  position: relative;
  overflow-x: hidden;
}

.bg-glow {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(650px circle at 12% -8%, #eead0026, transparent 60%),
    radial-gradient(500px circle at 92% 5%, #ee910022, transparent 55%);
}

header {
  position: relative;
  z-index: 1;
  max-width: 880px;
  margin: 0 auto;
  padding: 40px 24px 8px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 28px;
}
.brand-mark {
  width: 32px;
  height: 32px;
  border-radius: 9px;
  background: linear-gradient(to right, var(--accent-2), var(--accent));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 16px;
  color: #ffffff;
}
.brand-name {
  font-weight: 800;
  font-size: 16px;
  letter-spacing: -0.01em;
}
.brand-dot { color: var(--accent); font-weight: 700; }

.header-copy h1 {
  font-weight: 800;
  font-size: clamp(26px, 4vw, 38px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
  max-width: 640px;
  color: var(--text);
}
.subtitle {
  color: var(--muted);
  font-size: 15px;
  line-height: 1.6;
  margin: 0 0 28px;
  max-width: 560px;
}

main {
  position: relative;
  z-index: 1;
  max-width: 880px;
  margin: 0 auto;
  padding: 0 24px 60px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px;
  box-shadow: var(--shadow);
}

.tabs {
  display: flex;
  gap: 4px;
  background: var(--bg);
  border: 1px solid var(--border-soft);
  border-radius: 999px;
  padding: 4px;
  margin-bottom: 18px;
  width: fit-content;
}
.tab-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  background: transparent;
  border: none;
  color: var(--muted);
  border-radius: 999px;
  cursor: pointer;
  font-size: 13.5px;
  font-weight: 700;
  font-family: inherit;
  transition: background 0.15s ease, color 0.15s ease;
}
.tab-btn:hover { color: var(--text); }
.tab-btn.active {
  background: var(--accent-soft-strong);
  color: var(--accent);
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

textarea {
  width: 100%;
  min-height: 240px;
  background: var(--bg);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  color: var(--text);
  padding: 16px;
  font-size: 14.5px;
  font-family: inherit;
  line-height: 1.6;
  resize: vertical;
  transition: border-color 0.15s ease;
}
textarea:focus {
  outline: none;
  border-color: var(--accent);
}
textarea::placeholder { color: var(--muted-2); }

.dropzone {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  text-align: center;
  min-height: 200px;
  border: 1.5px dashed var(--border);
  border-radius: var(--radius-md);
  background: var(--bg);
  color: var(--muted);
  cursor: pointer;
  padding: 24px;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.dropzone svg { color: var(--muted-2); margin-bottom: 4px; }
.dropzone:hover, .dropzone.drag-over {
  border-color: var(--accent);
  background: var(--accent-soft);
}
.dropzone-text { font-size: 14px; color: var(--text); }
.dropzone-text strong { color: var(--accent); font-weight: 700; }
.dropzone-hint { font-size: 12.5px; color: var(--muted-2); }
.file-chosen {
  margin-top: 6px;
  font-size: 13px;
  color: var(--accent);
  font-weight: 700;
  background: var(--accent-soft-strong);
  padding: 6px 12px;
  border-radius: 999px;
}
.file-chosen.hidden { display: none; }

.plagiarism-hint {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.6;
  margin: 0 0 16px;
  background: var(--accent-soft);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.dropzone-group { display: flex; flex-direction: column; gap: 8px; }
.dropzone-label { font-size: 12.5px; font-weight: 700; color: var(--text); }
.dropzone-sm { min-height: 140px; padding: 16px; }

@media (max-width: 560px) {
  .two-col { grid-template-columns: 1fr; }
}

.level-picker { margin-top: 20px; }
.level-picker.hidden { display: none; }
.level-label {
  display: block;
  font-size: 12.5px;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
}
.level-options {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}
.level-opt {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  background: var(--bg);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  cursor: pointer;
  font-family: inherit;
  text-align: left;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.level-opt:hover { border-color: var(--muted-2); }
.level-opt.active {
  border-color: var(--accent);
  background: var(--accent-soft-strong);
}
.level-title { font-size: 13.5px; font-weight: 700; color: var(--text); }
.level-desc { font-size: 11.5px; color: var(--muted); }
.level-opt.active .level-title { color: var(--accent); }

.submit-btn {
  width: 100%;
  margin-top: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: linear-gradient(to right, var(--accent-2), var(--accent));
  color: #ffffff;
  border: none;
  border-radius: var(--radius-md);
  padding: 14px;
  font-size: 14.5px;
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
  box-shadow: 0 12px 24px -10px #ee910066;
  transition: filter 0.15s ease, transform 0.1s ease;
}
.submit-btn:hover:not(:disabled) { filter: brightness(1.05); }
.submit-btn:active:not(:disabled) { transform: scale(0.99); }
.submit-btn:disabled { opacity: 0.6; cursor: not-allowed; }

.btn-spinner {
  width: 15px;
  height: 15px;
  border: 2px solid #ffffff66;
  border-top-color: #ffffff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}
.btn-spinner.hidden { display: none; }
@keyframes spin { to { transform: rotate(360deg); } }

.status {
  margin-top: 14px;
  font-size: 13.5px;
  color: var(--muted);
  min-height: 18px;
  text-align: center;
}
.status.error { color: var(--rm-text); }
.status.success { color: var(--add-text); }

.results { margin-top: 32px; }
.results.hidden { display: none; }
.results-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.results-header h2 {
  font-size: 20px;
  font-weight: 800;
  margin: 0 0 4px;
}
.results-meta { color: var(--muted); font-size: 13px; margin: 0; }

.download-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  font-size: 13.5px;
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
  transition: border-color 0.15s ease;
}
.download-btn:hover { border-color: var(--accent); color: var(--accent); }

.legend {
  display: flex;
  gap: 16px;
  margin: 14px 0 4px;
}
.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--muted);
}
.dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
.dot.rm { background: var(--rm-text); }
.dot.add { background: var(--add-text); }

#diffList { margin-top: 12px; display: flex; flex-direction: column; gap: 14px; }
.para-block {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  box-shadow: 0 10px 24px -18px rgba(60, 45, 10, 0.15);
}
.para-label {
  font-size: 10.5px;
  text-transform: uppercase;
  color: var(--muted-2);
  margin-bottom: 8px;
  letter-spacing: 0.08em;
  font-weight: 800;
}
.para-orig, .para-result { line-height: 1.7; font-size: 14px; }
.para-orig { color: var(--muted); margin-bottom: 10px; padding-bottom: 10px; border-bottom: 1px dashed var(--border-soft); }
.para-result { color: var(--text); }
span.rm { background: var(--rm-bg); color: var(--rm-text); text-decoration: line-through; border-radius: 4px; padding: 1px 3px; }
span.add { background: var(--add-bg); color: var(--add-text); border-radius: 4px; padding: 1px 3px; }

footer {
  position: relative;
  z-index: 1;
  text-align: center;
  color: var(--muted-2);
  font-size: 12.5px;
  padding: 20px;
}

@media (max-width: 560px) {
  .level-options { grid-template-columns: 1fr; }
  .results-header { flex-direction: column; }
  .download-btn { width: 100%; justify-content: center; }
}