:root {
  --bg-color: #ffffff;
  --text-color: #333333;
  --card-bg: #f8f9fa;
  --input-bg: #ffffff;
  --input-border: #dddddd;
  --accent-color: #007bff;
}

html[data-theme='dark'] {
  --bg-color: #121212;
  --text-color: #e0e0e0;
  --card-bg: #1e1e1e;
  --input-bg: #2d2d2d;
  --input-border: #444444;
  --accent-color: #3793ff;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
  transition: background-color 0.3s, color 0.3s;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.container {
  padding: 2rem;
  border-radius: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  background-color: var(--card-bg);
  width: 100%;
  max-width: 450px;
  margin: 20px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

h1 { font-size: 1.5rem; margin: 0; }
h2 { font-size: 1.2rem; margin-bottom: 1.5rem; }

#theme-toggle {
  background: none;
  font-size: 1.8rem;
  padding: 0;
  border: none;
  cursor: pointer;
}

.intro {
  margin-bottom: 2rem;
  opacity: 0.8;
}

.form-group {
  margin-bottom: 1.2rem;
  text-align: left;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
  font-weight: 600;
}

.form-group input, 
.form-group textarea {
  width: 100%;
  padding: 0.8rem;
  border-radius: 8px;
  border: 1px solid var(--input-border);
  background-color: var(--input-bg);
  color: var(--text-color);
  box-sizing: border-box;
  font-size: 1rem;
}

.form-group input:focus, 
.form-group textarea:focus {
  outline: 2px solid var(--accent-color);
  border-color: transparent;
}

button[type="submit"] {
  width: 100%;
  padding: 1rem;
  background-color: var(--accent-color);
  color: white;
  border: none;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
  transition: opacity 0.2s;
}

button[type="submit"]:hover {
  opacity: 0.9;
}