:root {
  --green: #07432e;
  --green-dark: #04301f;
  --red: #8a1a1a;
  --red-bright: #c62020;
  --bg: #0b0d0c;
  --bg-2: #13171a;
  --bg-3: #1c2025;
  --fg: #f3f5f4;
  --fg-dim: #9aa3a0;
  --border: #262b2e;
  --radius: 14px;
  --radius-lg: 18px;
  --shadow: 0 10px 40px rgba(0, 0, 0, 0.6);
  --tap: 48px; 

  --sa-top:    env(safe-area-inset-top, 0px);
  --sa-right:  env(safe-area-inset-right, 0px);
  --sa-bottom: env(safe-area-inset-bottom, 0px);
  --sa-left:   env(safe-area-inset-left, 0px);
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "SF Pro Text",
               "Noto Sans Bengali", "Segoe UI", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  overscroll-behavior-y: none;
}

body {
  min-height: 100vh;
  min-height: 100dvh;
  background:
    radial-gradient(ellipse at top, rgba(7, 67, 46, 0.35), transparent 60%),
    radial-gradient(ellipse at bottom, rgba(7, 67, 46, 0.15), transparent 60%),
    var(--bg);
  display: flex;
  flex-direction: column;
  padding-top: var(--sa-top);
  padding-left: var(--sa-left);
  padding-right: var(--sa-right);
  padding-bottom: var(--sa-bottom);
}


.site-header {
  text-align: center;
  padding: 24px 16px 4px;
}
.site-header h1 {
  margin: 0 0 6px;
  font-size: clamp(20px, 5.5vw, 32px);
  font-weight: 800;
  letter-spacing: -0.02em;
  display: flex;
  flex-direction: column;
  gap: 2px;
  line-height: 1.15;
}
.site-header h1 .bn {
  color: #26b670;
}
.site-header h1 .en {
  color: var(--fg);
  font-size: 0.68em;
  font-weight: 600;
  letter-spacing: 0.05em;
}
.tagline {
  margin: 0;
  color: var(--fg-dim);
  font-size: clamp(12px, 3.2vw, 14px);
  letter-spacing: 0.02em;
}


.editor {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 16px 16px 32px;
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
}


.canvas-stage {
  width: 100%;
  display: flex;
  justify-content: center;
}
.canvas-wrap {
  position: relative;
  width: 100%;
  
  max-width: min(560px, calc(100dvh - 340px));
  aspect-ratio: 1 / 1;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background:
    linear-gradient(135deg, #1a1d1b 25%, transparent 25%) -10px 0 / 20px 20px,
    linear-gradient(225deg, #1a1d1b 25%, transparent 25%) -10px 0 / 20px 20px,
    linear-gradient(315deg, #1a1d1b 25%, transparent 25%) 0 0 / 20px 20px,
    linear-gradient(45deg,  #1a1d1b 25%, transparent 25%) 0 0 / 20px 20px,
    var(--bg-2);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}

#canvas {
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
  cursor: grab;
  user-select: none;
  -webkit-user-select: none;
  -webkit-user-drag: none;
}
#canvas.dragging { cursor: grabbing; }
#canvas.empty { cursor: pointer; }

.empty-hint {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--fg-dim);
  pointer-events: none;
  text-align: center;
  padding: 20px;
}
.empty-hint p {
  margin: 0;
  font-size: 13px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.empty-hint .bn {
  font-size: 15px;
  color: var(--fg);
  font-weight: 600;
}
.empty-hint.hidden { display: none; }


.controls {
  width: 100%;
  max-width: 560px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.control-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.file-row { justify-content: space-between; }


.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: var(--tap);
  padding: 12px 18px;
  border-radius: 12px;
  border: 1px solid transparent;
  font-size: 15px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: transform 0.08s ease, background 0.15s ease,
              border-color 0.15s ease, opacity 0.15s ease,
              box-shadow 0.15s ease;
  user-select: none;
  touch-action: manipulation;
}
.btn:active:not(:disabled) { transform: scale(0.97); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-primary {
  background: var(--green);
  color: #fff;
  flex: 1;
}
.btn-primary:hover:not(:disabled) { background: #0a553a; }

.btn-ghost {
  background: var(--bg-3);
  color: var(--fg);
  border-color: var(--border);
  padding: 12px 14px;
}
.btn-ghost:hover:not(:disabled) {
  background: #252a2f;
  border-color: #353b40;
}

.btn-download {
  background: linear-gradient(180deg, #0a553a, var(--green));
  color: #fff;
  padding: 16px 22px;
  font-size: 17px;
  font-weight: 700;
  min-height: 56px;
  box-shadow: 0 6px 24px rgba(7, 67, 46, 0.55);
  margin-top: 4px;
}
.btn-download:hover:not(:disabled) {
  background: linear-gradient(180deg, #0c6344, #0a553a);
  box-shadow: 0 8px 32px rgba(7, 67, 46, 0.7);
}


.slider-row {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
  flex-direction: column;
  align-items: stretch;
  gap: 10px;
}
.slider-row label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 14px;
}
.label-text { color: var(--fg-dim); font-weight: 500; }
.label-value {
  color: var(--fg);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: var(--bg-3);
  border-radius: 999px;
  outline: none;
  
  padding: 14px 0;
  margin: -14px 0;
}
input[type="range"]:disabled { opacity: 0.4; }
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #26b670;
  border: 3px solid #fff;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
  transition: transform 0.1s ease;
}
input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.1); }
input[type="range"]::-moz-range-thumb {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #26b670;
  border: 3px solid #fff;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
}

.tip {
  margin: 0;
  text-align: center;
  font-size: 12px;
  color: var(--fg-dim);
  line-height: 1.6;
}
.tip .bn { display: block; color: var(--fg); margin-bottom: 2px; font-size: 13px; }


.toast {
  position: fixed;
  bottom: calc(24px + var(--sa-bottom));
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--bg-3);
  color: var(--fg);
  padding: 12px 20px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease, transform 0.25s ease;
  z-index: 100;
  max-width: calc(100vw - 40px);
  text-align: center;
}
.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}


@media (max-width: 380px) {
  .site-header { padding: 18px 12px 2px; }
  .editor { padding: 12px 12px 24px; gap: 12px; }
  .tagline { display: none; }
  .btn-primary span { font-size: 14px; }
  .btn-download { padding: 14px 18px; font-size: 16px; }
}


@media (max-height: 640px) and (orientation: landscape) {
  .site-header {
    padding: 10px 16px 2px;
  }
  .site-header h1 {
    font-size: 18px;
    flex-direction: row;
    justify-content: center;
    gap: 8px;
    align-items: baseline;
  }
  .site-header h1 .en { font-size: 0.75em; }
  .tagline { display: none; }

  .editor {
    flex-direction: row;
    align-items: flex-start;
    max-width: 920px;
    padding: 8px 16px 16px;
    gap: 16px;
  }
  .canvas-wrap {
    max-width: min(420px, calc(100dvh - 140px));
  }
  .controls {
    flex: 1;
    max-width: 340px;
  }
  .btn-download { margin-top: 0; }
}


@media (min-width: 760px) and (orientation: portrait),
       (min-width: 900px) {
  .site-header { padding: 32px 20px 6px; }
  .editor {
    max-width: 920px;
    flex-direction: row;
    align-items: flex-start;
    padding: 28px 24px 48px;
    gap: 28px;
  }
  .canvas-stage { flex: 0 0 auto; }
  .canvas-wrap {
    width: 480px;
    max-width: none;
  }
  .controls {
    flex: 1;
    max-width: 340px;
    gap: 14px;
  }
}


@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition: none !important;
    animation: none !important;
  }
}