:root {
  --bg-color: #eaf4ff;
  --text-color: #0b2545;
  --card-bg: #ffffff;
  --border-color: #b8dcf5;
  --accent: #2e9be6;
  --error-color: #d64545;
  --success-color: #1f9d55;
  --input-bg: #ffffff;
}

body.dark-mode {
  --bg-color: #0d1b3f;
  --text-color: #e6f0ff;
  --card-bg: #0d1b3f;
  --border-color: #1f3268;
  --accent: #5c8dff;
  --error-color: #ff6b6b;
  --success-color: #4ade80;
  --input-bg: #122552;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
transition: background-color 0.25s ease, color 0.25s ease;
  min-height: 100vh;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 15px 20px;
  border-bottom: 1px solid var(--border-color);
}

.topbar h1 {
  font-size: 1.4rem;
  margin: 0;
}

#themeToggle {
  background-color: var(--card-bg);
  color: var(--text-color);
  border: 1px solid var(--border-color);
  padding: 8px 16px;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: background-color 0.2s ease, transform 0.15s ease;
}

#themeToggle:hover {
  transform: translateY(-1px);
}

main {
  display: flex;
  justify-content: center;
  padding: 30px 20px;
}

#contactForm {
  width: 100%;
  max-width: 480px;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 32px;
  transition: background-color 0.25s ease, border-color 0.25s ease;
}

.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 6px;
  font-weight: 600;
  font-size: 0.9rem;
}

input,
textarea {
  width: 100%;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: var(--input-bg);
  color: var(--text-color);
  font-size: 0.95rem;
  font-family: inherit;
  resize: vertical;
  transition: border-color 0.2s ease;
}

input:focus,
textarea:focus {
  outline: none;
  border-color: var(--accent);
}

input.invalid,
textarea.invalid {
  border-color: var(--error-color);
}

.error {
  color: var(--error-color);
  font-size: 0.8rem;
  margin: 6px 0 0;
  min-height: 1em;
}

.submit-btn {
  width: 100%;
  padding: 12px;
  border: none;
  border-radius: 8px;
  background-color: var(--accent);
  color: #ffffff;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s ease;
}

.submit-btn:hover {
  opacity: 0.9;
}

.success {
  color: var(--success-color);
  text-align: center;
  font-weight: 600;
  margin-top: 16px;
  min-height: 1em;
}