:root {
  --bg-color: #f0f2f5;
  --bg-dot-color: #d7d7d7;
  --card-bg: white;
  --card-shadow: rgba(0, 0, 0, 0.1);
  --text-primary: #2c3e50;
  --text-body: #333;
  --border-color: #e2e8f0;
  --input-bg: #f8fafc;
  --btn-bg: #f97316;
  --btn-hover: #ea6c0a;
  --btn-shadow: rgba(249, 115, 22, 0.35);
  --btn-hover-shadow: rgba(234, 108, 10, 0.45);
  --toggle-bg: #e2e8f0;
}

body.dark {
  --bg-color: #0f172a;
  --bg-dot-color: #1e293b;
  --card-bg: #1e293b;
  --card-shadow: rgba(0, 0, 0, 0.4);
  --text-primary: #e2e8f0;
  --text-body: #cbd5e1;
  --border-color: #334155;
  --input-bg: #0f172a;
  --btn-bg: #f97316;
  --btn-hover: #ea6c0a;
  --btn-shadow: rgba(249, 115, 22, 0.35);
  --btn-hover-shadow: rgba(234, 108, 10, 0.45);
  --toggle-bg: #334155;
}

* {
  box-sizing: border-box;
}

body {
  font-family: 'Helvetica Neue', sans-serif;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
  background-color: var(--bg-color);
  background-image: radial-gradient(var(--bg-dot-color) 1px, transparent 0);
  background-size: 40px 40px;
  margin: 0;
  padding: 3rem 1rem;
  color: var(--text-body);
  transition: background-color 0.3s ease, color 0.3s ease;
}

#theme-toggle {
  position: fixed;
  top: 1.2rem;
  right: 1.2rem;
  background-color: var(--toggle-bg);
  border: none;
  border-radius: 50%;
  width: 44px;
  height: 44px;
  font-size: 1.3rem;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  transition: background-color 0.3s ease, transform 0.2s ease;
  z-index: 100;
}

#theme-toggle:hover {
  transform: scale(1.1);
}

.form-container {
  background: var(--card-bg);
  padding: 2.5rem 3rem;
  border-radius: 16px;
  box-shadow: 0 10px 30px var(--card-shadow);
  width: 100%;
  max-width: 500px;
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
  font-size: 2rem;
  font-weight: bold;
  color: var(--text-primary);
  text-align: center;
  margin: 0 0 0.4rem;
  transition: color 0.3s ease;
}

.subtitle {
  text-align: center;
  font-size: 0.9rem;
  color: var(--text-body);
  opacity: 0.7;
  margin: 0 0 2rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1.2rem;
}

.form-group label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
  padding: 0.75rem 1rem;
  border: 1.5px solid var(--border-color);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
  background-color: var(--input-bg);
  color: var(--text-body);
  transition: border-color 0.2s ease, background-color 0.3s ease;
  outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--btn-bg);
}

.form-group textarea {
  resize: vertical;
  min-height: 100px;
}

#submit-btn {
  width: 100%;
  background-color: var(--btn-bg);
  color: white;
  border: none;
  padding: 0.9rem;
  font-size: 1.1rem;
  font-weight: 600;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 4px 15px var(--btn-shadow);
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
  margin-top: 0.5rem;
}

#submit-btn:hover {
  background-color: var(--btn-hover);
  box-shadow: 0 6px 20px var(--btn-hover-shadow);
}

#submit-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.success-msg {
  display: none;
  text-align: center;
  padding: 2rem 1rem;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.8;
}

@media (max-width: 540px) {
  .form-container {
    padding: 2rem 1.5rem;
  }

  h1 {
    font-size: 1.6rem;
  }
}