:root {
  --bg: #f4f6fa;
  --text: #1f2937;
  --card: #ffffff;
  --accent: #2563eb;
  --shadow: 0 4px 14px rgba(0, 0, 0, 0.08);
}

body.dark {
  --bg: #0f172a;
  --text: #f1f5f9;
  --card: #1e293b;
  --accent: #3b82f6;
  --shadow: 0 4px 14px rgba(255, 255, 255, 0.05);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  transition: background 0.3s, color 0.3s;
}

header.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  background-color: var(--card);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}

header.header h1 {
  flex: 1;
  text-align: center;
  font-size: 1.8rem;
  margin: 0;
  font-weight: 600;
}

header.header .logo {
  height: 48px;
  object-fit: contain;
}

#toggleThemeBtn {
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--accent);
  transition: transform 0.3s ease;
}

#toggleThemeBtn:hover {
  transform: scale(1.1);
}

.app-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 2rem;
  padding: 2rem 1rem;
  max-width: 1200px;
  margin: 0 auto;
}

.card {
  background: var(--card);
  box-shadow: var(--shadow);
  border-radius: 16px;
  padding: 1.5rem;
  transition: transform 0.3s ease;
  flex: 1 1 400px;
  max-width: 640px;
  width: 100%;
}

.card:hover {
  transform: translateY(-4px);
}

/* Camera & Canvas */
.camera-card video,
.camera-card canvas {
  width: 100%;
  border-radius: 12px;
  border: 2px solid #ccc;
  margin-bottom: 1rem;
}

#gesture-label {
  font-size: 1.25rem;
  text-align: center;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

#ghost-label {
  text-align: center;
  font-style: italic;
  opacity: 0.6;
  font-size: 0.9rem;
}

/* Input and Buttons */
input[type="text"], input[type="file"] {
  width: 100%;
  max-width: 300px;
  padding: 0.6rem;
  font-size: 1rem;
  border-radius: 8px;
  border: 1px solid #ccc;
  margin: 0.5rem 0;
  background-color: white;
}

body.dark input[type="text"],
body.dark input[type="file"] {
  background: #334155;
  color: #fff;
  border: 1px solid #555;
}

button {
  background-color: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  padding: 0.6rem 1rem;
  font-size: 1rem;
  cursor: pointer;
  margin: 0.4rem 0.3rem;
  transition: background-color 0.3s ease, transform 0.2s ease;
}

button:hover {
  background-color: #1d4ed8;
  transform: scale(1.05);
}

/* Sentence Bubble Section */
#sentence-container {
  background: var(--card);
  box-shadow: var(--shadow);
  border-radius: 12px;
  padding: 1rem;
  margin-top: 1rem;
  text-align: center;
}

#sentence-bubbles {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  justify-content: center;
  margin: 1rem 0;
}

.bubble {
  background-color: var(--accent);
  color: #fff;
  padding: 8px 14px;
  border-radius: 9999px;
  font-weight: 500;
  animation: fadeIn 0.3s ease-in-out;
}
.sentence-buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
}

/* History and Gesture List */
#history, #savedGesturesList {
  background: var(--card);
  box-shadow: var(--shadow);
  border-radius: 12px;
  padding: 1rem;
  margin: 1rem auto;
  width: 95%;
  max-width: 800px;
  font-size: 1rem;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(0, 0, 0, 0.75);
  color: #fff;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  z-index: 999;
}

.toast.show {
  opacity: 1;
  pointer-events: auto;
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* Responsive Design */
@media (max-width: 768px) {
  .app-container {
    flex-direction: column;
    padding: 1rem;
  }

  .header {
    flex-direction: column;
    text-align: center;
    gap: 0.5rem;
  }

  .header h1 {
    font-size: 1.5rem;
  }

  button {
    width: 100%;
  }

  input[type="text"], input[type="file"] {
    width: 100%;
  }

  .bubble {
    font-size: 0.9rem;
  }

  #sentence-container,
  #history,
  #savedGesturesList {
    width: 100%;
  }
}
html {
  scroll-behavior: smooth;
}