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

:root {
  --green:       #1DB868;
  --green-light: #e6f7ef;
  --green-dark:  #148a4a;
  --text:        #1C1C1E;
  --text-2:      #3A3A3C;
  --text-3:      #6e6e73;
  --sep:         #e5e5ea;
  --bg:          #ffffff;
  --bg-2:        #f5f5f7;
  --radius:      18px;
  --radius-sm:   12px;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Hiragino Sans', sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  line-height: 1.5;
}

button, input, select { font: inherit; }

/* ── NAV ── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.82);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--sep);
}
.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.3px;
  color: var(--text);
  text-decoration: none;
}
.nav-logo span { color: var(--green); }
.nav-tool-name {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-3);
}

/* ── HERO ── */
.app-shell {
  max-width: 1100px;
  margin: 0 auto;
  padding: 56px 24px 72px;
}

.hero {
  text-align: center;
  margin-bottom: 48px;
}
.hero-badge {
  display: inline-block;
  background: var(--green-light);
  color: var(--green-dark);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.5px;
  padding: 5px 14px;
  border-radius: 100px;
  margin-bottom: 20px;
  text-transform: uppercase;
}
.hero h1 {
  font-size: clamp(28px, 5vw, 48px);
  font-weight: 700;
  letter-spacing: -1.5px;
  line-height: 1.1;
  color: var(--text);
  margin-bottom: 16px;
}
.hero h1 em {
  font-style: normal;
  color: var(--green);
}
.hero-copy {
  font-size: clamp(15px, 1.8vw, 17px);
  color: var(--text-3);
  max-width: 540px;
  margin: 0 auto;
  line-height: 1.65;
  font-weight: 400;
}

/* ── WORKSPACE ── */
.workspace {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

.controls {
  display: grid;
  gap: 12px;
}

/* ── PANEL ── */
.panel {
  background: var(--bg-2);
  border-radius: var(--radius);
  padding: 20px;
}

.panel label,
.stage-title {
  display: block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: -0.1px;
  color: var(--text-2);
  margin-bottom: 10px;
}

.hint,
.status {
  font-size: 12px;
  color: var(--text-3);
  line-height: 1.55;
  margin-top: 8px;
}

/* ── FILE PICKER ── */
.file-picker {
  position: relative;
  display: block;
  padding: 20px;
  border: 1.5px dashed rgba(29, 184, 104, 0.4);
  border-radius: var(--radius-sm);
  background: var(--green-light);
  cursor: pointer;
  text-align: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--green-dark);
  transition: transform 150ms ease, background 150ms ease, border-color 150ms ease;
}
.file-picker input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}
.file-picker.drag-over {
  transform: translateY(-2px);
  background: #d0f0e0;
  border-color: var(--green);
}

/* ── FORM CONTROLS ── */
select {
  width: 100%;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--sep);
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  margin-bottom: 12px;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--green);
  margin-bottom: 12px;
}

/* ── META GRID ── */
.meta-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}
.meta-label {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  color: var(--text-3);
}
.meta-grid strong,
.source-meta strong {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-top: 3px;
}

/* ── BUTTONS ── */
.button-row {
  display: flex;
  gap: 8px;
}
button {
  flex: 1;
  border: 0;
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  font-size: 14px;
  font-weight: 500;
  background: var(--bg);
  color: var(--text-2);
  cursor: pointer;
  transition: opacity 0.15s, transform 0.15s;
  border: 1px solid var(--sep);
}
button:hover:not(:disabled) {
  opacity: 0.78;
  transform: translateY(-1px);
}
button:disabled {
  cursor: not-allowed;
  opacity: 0.4;
}
button.primary {
  background: var(--text);
  color: #fff;
  border-color: transparent;
  font-weight: 600;
}
button.primary:hover:not(:disabled) {
  opacity: 0.82;
}

/* ── NOTE PANEL ── */
.note h2 {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.6px;
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: 12px;
}
.note ul {
  margin: 0;
  padding-left: 16px;
}
.note li {
  font-size: 12px;
  color: var(--text-3);
  line-height: 1.6;
}
.note li + li { margin-top: 6px; }

/* ── STAGE ── */
.stage-area {
  background: var(--bg-2);
  border-radius: var(--radius);
  padding: 20px;
}
.stage-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 16px;
  margin-bottom: 14px;
}
.stage-title {
  margin-bottom: 2px;
}
.stage-subtitle {
  font-size: 12px;
  color: var(--text-3);
}
.source-meta {
  text-align: right;
}
.source-meta span {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  color: var(--text-3);
}

.canvas-frame {
  position: relative;
  min-height: 600px;
  display: grid;
  place-items: center;
  border-radius: 14px;
  overflow: hidden;
  background:
    linear-gradient(45deg, rgba(0,0,0,0.03) 25%, transparent 25%, transparent 75%, rgba(0,0,0,0.03) 75%),
    linear-gradient(45deg, rgba(0,0,0,0.03) 25%, transparent 25%, transparent 75%, rgba(0,0,0,0.03) 75%),
    var(--bg);
  background-size: 20px 20px;
  background-position: 0 0, 10px 10px;
  border: 1px solid var(--sep);
}

#previewCanvas {
  max-width: 100%;
  max-height: 70vh;
  display: block;
  border-radius: 12px;
  box-shadow: 0 12px 32px rgba(0,0,0,0.10);
  cursor: grab;
}
#previewCanvas.dragging { cursor: grabbing; }

.empty-state {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  text-align: center;
  padding: 24px;
  color: var(--text-3);
  font-size: 14px;
  pointer-events: none;
}

/* ── FOOTER ── */
footer {
  border-top: 1px solid var(--sep);
  margin-top: 0;
}
.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.footer-copy {
  font-size: 13px;
  color: var(--text-3);
}
.footer-link {
  font-size: 13px;
  color: var(--green);
  text-decoration: none;
}
.footer-link:hover { opacity: 0.7; }

/* ── RESPONSIVE ── */
@media (max-width: 900px) {
  .workspace {
    grid-template-columns: 1fr;
  }
  .canvas-frame {
    min-height: 440px;
  }
}

@media (max-width: 600px) {
  .app-shell {
    padding: 32px 16px 56px;
  }
  .button-row,
  .stage-header {
    flex-direction: column;
    align-items: stretch;
  }
  .source-meta { text-align: left; }
  .canvas-frame {
    min-height: 320px;
  }
  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}