:root {
  --primary: #2D6A4F;
  --primary-dark: #1B4332;
  --primary-light: #D8E9DF;
  --accent: #F4A261;
  --accent-dark: #E08A3C;
  --bg: #FAF8F4;
  --surface: #FFFFFF;
  --text: #1F2937;
  --text-muted: #6B7280;
  --border: #E5E7EB;
  --border-strong: #D1D5DB;
  --success: #2D6A4F;
  --danger: #DC2626;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.04);
  --shadow: 0 4px 12px rgba(0,0,0,.06);
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Microsoft JhengHei", "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

.container {
  width: 100%;
  max-width: 880px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  padding: 32px 0 28px;
}
.site-header h1 {
  margin: 0 0 8px;
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.site-header .subtitle {
  margin: 0;
  font-size: 15px;
  line-height: 1.6;
  opacity: 0.92;
}

/* Main spacing */
main { padding: 24px 0 8px; }

/* Visually hidden but still focusable / clickable (used for file input) */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Dropzone */
.dropzone {
  display: block;
  background: var(--surface);
  border: 2px dashed var(--border-strong);
  border-radius: var(--radius);
  padding: 36px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color .15s, background .15s, transform .05s;
  margin-bottom: 16px;
  -webkit-tap-highlight-color: rgba(45, 106, 79, 0.1);
}
.dropzone:hover {
  border-color: var(--primary);
  background: #FCFBF7;
}
.dropzone.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
}
.dropzone.processing {
  border-color: var(--primary);
  background: var(--primary-light);
  cursor: progress;
}
.dropzone.received {
  border-color: var(--primary);
  background: var(--primary-light);
}
.dropzone.received .dropzone-icon,
.dropzone.processing .dropzone-icon {
  color: var(--primary-dark);
  animation: pulse 1.4s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(0.92); }
}
.dropzone-icon {
  width: 44px;
  height: 44px;
  color: var(--primary);
  margin-bottom: 12px;
}
.dropzone-main {
  margin: 0 0 6px;
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
}
.dropzone-hint {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
}

/* Settings */
.settings {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-bottom: 16px;
  overflow: hidden;
}

/* Mode selector */
.mode-selector {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  padding: 12px;
}
.mode-btn {
  display: flex;
  flex-direction: column;
  gap: 2px;
  align-items: flex-start;
  padding: 12px 14px;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  text-align: left;
  transition: border-color .15s, background .15s;
  min-height: 60px;
  font-family: inherit;
}
.mode-btn:hover {
  border-color: var(--border-strong);
}
.mode-btn strong {
  font-size: 15px;
  color: var(--text);
  font-weight: 600;
}
.mode-btn span {
  font-size: 12px;
  color: var(--text-muted);
}
.mode-btn.active {
  background: var(--primary-light);
  border-color: var(--primary);
}
.mode-btn.active strong {
  color: var(--primary-dark);
}
.mode-btn.active span {
  color: var(--primary-dark);
  opacity: 0.8;
}

.advanced summary {
  list-style: none;
  cursor: pointer;
  padding: 14px 18px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
  user-select: none;
  min-height: 44px;
}
.advanced summary::-webkit-details-marker { display: none; }
.advanced summary svg { width: 18px; height: 18px; color: var(--text-muted); }
.advanced summary:hover { background: #FCFBF7; }
.advanced[open] summary { border-bottom: 1px solid var(--border); }

.advanced-body {
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.field { display: flex; flex-direction: column; gap: 8px; }
.field-label {
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
}
.field select,
.field input[type="range"] {
  width: 100%;
  font-size: 15px;
  min-height: 44px;
  padding: 0 12px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: #fff;
  color: var(--text);
}
.field input[type="range"] {
  padding: 0;
  border: none;
  background: transparent;
  min-height: 32px;
}
.range-labels {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
}

/* Results */
.results {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 18px;
  margin-bottom: 32px;
}
.results-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 14px;
}
.summary {
  font-size: 14px;
  color: var(--text);
  line-height: 1.5;
}
.summary .saved {
  color: var(--primary);
  font-weight: 600;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  padding: 12px 18px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  min-height: 44px;
  transition: background .15s;
}
.btn-primary:hover { background: var(--primary-dark); }
.btn-primary svg { width: 16px; height: 16px; }
.btn-primary:disabled { background: var(--border-strong); cursor: not-allowed; }

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  font-size: 14px;
  cursor: pointer;
  min-height: 40px;
  width: 100%;
  margin-top: 8px;
}
.btn-ghost:hover { background: #FCFBF7; color: var(--text); }

.result-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.result-item {
  display: grid;
  grid-template-columns: 56px 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 10px;
  background: #FCFBF7;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}
.result-thumb {
  width: 56px;
  height: 56px;
  border-radius: 6px;
  object-fit: cover;
  background: var(--border);
}
.result-info { min-width: 0; }
.result-name {
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin: 0 0 4px;
}
.result-sizes {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
}
.result-sizes .saved {
  color: var(--primary);
  font-weight: 600;
}
.result-sizes .original { text-decoration: line-through; }
.result-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--primary);
  border: 1px solid var(--border);
  cursor: pointer;
  text-decoration: none;
}
.result-action:hover { background: var(--primary-light); }
.result-action svg { width: 18px; height: 18px; }
.result-status {
  font-size: 13px;
  color: var(--text-muted);
}
.result-status.error { color: var(--danger); }

/* Education */
.education {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 40px 0 48px;
}
.education h2 {
  font-size: 20px;
  margin: 0 0 16px;
  color: var(--primary-dark);
  letter-spacing: -0.01em;
}
.education h2:not(:first-child) {
  margin-top: 36px;
}
.edu-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin-bottom: 8px;
}
.edu-card {
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
}
.edu-card h3 {
  margin: 0 0 6px;
  font-size: 15px;
  color: var(--text);
}
.edu-card p {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.7;
}
.edu-block {
  margin-bottom: 16px;
}
.edu-block h3 {
  margin: 0 0 6px;
  font-size: 15px;
  color: var(--text);
}
.edu-block p {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.7;
}
.edu-list {
  margin: 0 0 12px;
  padding-left: 22px;
  font-size: 14px;
  color: var(--text);
  line-height: 1.8;
}
.edu-tip {
  background: var(--primary-light);
  color: var(--primary-dark);
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  margin: 0;
}

/* Footer */
.site-footer {
  background: #1F2937;
  color: #D1D5DB;
  padding: 24px 0;
  font-size: 13px;
  text-align: center;
}
.site-footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}
.site-footer a:hover { text-decoration: underline; }

/* Tablet and up */
@media (min-width: 640px) {
  .container { padding: 0 24px; }
  .site-header { padding: 48px 0 40px; }
  .site-header h1 { font-size: 32px; }
  .site-header .subtitle { font-size: 16px; }
  main { padding: 32px 0 16px; }
  .dropzone { padding: 56px 24px; }
  .dropzone-icon { width: 52px; height: 52px; }
  .dropzone-main { font-size: 17px; }
  .results-header {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
  .edu-grid {
    grid-template-columns: 1fr 1fr;
    gap: 16px;
  }
  .education { padding: 56px 0 64px; }
  .education h2 { font-size: 22px; }
}

/* Desktop */
@media (min-width: 960px) {
  .site-header h1 { font-size: 36px; }
}