:root {
  --bg-dark: #050608;
  --bg-light: #f4f4f7;

  --text-dark: #f9fafb;
  --text-light: #111827;

  --card-dark: #111827;
  --card-light: #ffffff;

  --border-dark: #1f2937;
  --border-light: #d1d5db;

  --accent: #6ec1e4;
}

/* GLOBAL */

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

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 32px 16px 40px;
  transition: background 0.3s ease, color 0.3s ease;
}

body.dark {
  background: radial-gradient(circle at top, #111827 0, #020617 60%);
  color: var(--text-dark);
}

body.light {
  background: radial-gradient(circle at top, #ffffff 0, #e5e7eb 60%);
  color: var(--text-light);
}

/* WIDTH */

h1,
p,
.controls,
textarea,
.overlay,
a,
footer {
  width: min(900px, 100%);
}

/* HEADER */

h1 {
  margin: 0 0 8px;
  font-size: 2rem;
  text-align: center;
}

p {
  margin: 0 0 18px;
  font-size: 0.95rem;
  text-align: center;
  opacity: 0.9;
}

/* CONTROLS */

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-bottom: 16px;
}

.controls label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.controls input[type="color"],
.controls input[type="range"] {
  padding: 4px 6px;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.7);
  background: rgba(15, 23, 42, 0.95);
  cursor: pointer;
}

body.light .controls input[type="color"],
body.light .controls input[type="range"] {
  background: #ffffff;
}

/* TEXTAREA */

textarea {
  width: 100%;
  min-height: 160px;
  border-radius: 14px;
  border: 1px solid rgba(148, 163, 184, 0.75);
  padding: 14px 12px;
  resize: vertical;
  font-size: 0.96rem;
  font-family: inherit;
  background: rgba(15, 23, 42, 0.95);
  color: var(--text-dark);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.55);
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

body.light textarea {
  background: #ffffff;
  color: var(--text-light);
  box-shadow: 0 14px 28px rgba(15, 23, 42, 0.12);
}

textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 1px rgba(110, 193, 228, 0.6);
}

/* OVERLAY */

.overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  mix-blend-mode: multiply;
}

/* LINK & FOOTER */

a {
  margin-top: 22px;
  font-size: 0.9rem;
  color: var(--accent);
  text-decoration: none;
  text-align: center;
  position: relative;
  z-index: 1; /* above overlay */
}

a:hover {
  text-decoration: underline;
}

footer {
  position: relative;
  z-index: 1;
  margin-top: 26px;
  font-size: 0.85rem;
  text-align: center;
  opacity: 0.75;
}

/* RESPONSIVE */

@media (max-width: 640px) {
  .controls {
    flex-direction: column;
    align-items: stretch;
  }

  .controls label {
    justify-content: space-between;
  }
}