:root {
    --primary-color: #6366f1; /* Indigo 500 */
    --primary-hover: #4f46e5; /* Indigo 600 */
    --background-dark: #111827; /* Gray 900 */
    --surface-dark: #1f2937; /* Gray 800 */
    --text-primary: #f3f4f6; /* Gray 100 */
    --text-secondary: #9ca3af; /* Gray 400 */
    --error-color: #ef4444; /* Red 500 */
    --success-color: #10b981; /* Emerald 500 */
    --border-radius: 12px;
    --transition-speed: 0.3s;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-dark);
    color: var(--text-primary);
    margin: 0;
    padding: 0;
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Utilities */
.hidden { display: none !important; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.w-full { width: 100%; }
.h-screen { height: 100vh; }
.text-center { text-align: center; }
.mt-4 { margin-top: 1rem; }
.mb-4 { margin-bottom: 1rem; }
.p-4 { padding: 1rem; }

/* Buttons */
.btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: background-color var(--transition-speed);
    font-size: 1rem;
}

.btn:hover {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: transparent;
    border: 1px solid var(--text-secondary);
    color: var(--text-secondary);
}

.btn-secondary:hover {
    border-color: var(--text-primary);
    color: var(--text-primary);
}

/* Forms */
.input-group {
    margin-bottom: 1rem;
    width: 100%;
    max-width: 400px;
}

input {
    width: 100%;
    padding: 0.75rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--surface-dark);
    background-color: var(--surface-dark);
    color: var(--text-primary);
    font-size: 1rem;
    box-sizing: border-box; /* Important for padding */
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

/* Cards */
.card {
    background-color: var(--surface-dark);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
    animation: fadeIn 0.5s ease-out forwards;
}

/* Navigation */
nav {
    background-color: var(--surface-dark);
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    margin-left: 1rem;
    font-weight: 500;
    transition: color 0.2s;
}

nav a:hover, nav a.active {
    color: var(--primary-color);
}