:root {
  --color-primary: #6a5acd;
  --color-secondary: #f0f2f5;
  --color-background: #121212;
  --color-card-background: #1e1e1e;
  --color-text: #e0e0e0;
  --color-text-muted: #a0a0a0;
  --font-family-main: 'Noto Sans KR', 'Inter', sans-serif;
  --shadow-deep: 0 10px 20px rgba(0, 0, 0, 0.4), 0 6px 6px rgba(0, 0, 0, 0.3);
  --shadow-lifted: 0 4px 8px rgba(0, 0, 0, 0.3);
  --glow-effect: 0 0 15px rgba(106, 90, 205, 0.7);
}

body {
  font-family: var(--font-family-main);
  background-color: var(--color-background);
  color: var(--color-text);
  margin: 0;
  padding: 2rem;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-image: url('data:image/svg+xml,%3Csvg width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"%3E%3Cg fill="%231a1a1a"%3E%3Crect x="0" y="0" width="100" height="100"/%3E%3C/g%3E%3C/svg%3E');
}

.container {
  width: 100%;
  max-width: 600px;
}

.card {
  background-color: var(--color-card-background);
  border-radius: 16px;
  box-shadow: var(--shadow-deep);
  overflow: hidden;
}

.card-header {
  text-align: center;
  padding: 2rem;
  border-bottom: 1px solid #333;
}

.card-header h1 {
  font-size: 2.5rem;
  font-weight: 900;
  margin: 0 0 0.5rem;
  color: var(--color-primary);
}

.card-header p {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  margin: 0;
}

.card-body {
  padding: 2rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

label {
  display: block;
  margin-bottom: 0.75rem;
  font-weight: 700;
  font-size: 1.1rem;
}

.link-input {
  display: flex;
  margin-bottom: 0.75rem;
}

.link-input input,
textarea {
  width: 100%;
  padding: 1rem;
  border: 1px solid #333;
  border-radius: 8px;
  font-size: 1rem;
  background-color: #2c2c2c;
  color: var(--color-text);
  transition: border-color 0.2s, box-shadow 0.2s;
  box-sizing: border-box;
}

.link-input input:focus,
textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--glow-effect);
}

textarea {
  resize: vertical;
  min-height: 80px;
}

.form-actions {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
}

button {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem 1.5rem;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
  box-shadow: var(--shadow-lifted);
}

button span {
  margin: 0 0.5rem;
}

#add-link-btn {
  background-color: #444;
  color: var(--color-text);
  flex-grow: 1;
}

#add-link-btn:hover {
  background-color: #555;
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.4);
}

button[type="submit"] {
  background-color: var(--color-primary);
  color: #fff;
  flex-grow: 1;
}

button[type="submit"]:hover {
  background-color: #7a6be0;
  transform: translateY(-2px);
  box-shadow: var(--shadow-lifted), var(--glow-effect);
}

@media (max-width: 600px) {
  body {
    padding: 1rem;
  }
  .form-actions {
    flex-direction: column;
  }
}