@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
    --primary-color: #6366f1; /* Indigo */
    --primary-hover: #4f46e5;
    --bg-color: #0f172a; /* Slate 900 */
    --surface-color: #1e293b; /* Slate 800 */
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    
    --success-color: #10b981;
    --danger-color: #ef4444;

    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* NAVBAR */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 5%;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

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

/* MAIN CONTAINER */
.hero-section {
    text-align: center;
    padding: 6rem 5%;
    background: radial-gradient(circle at top, #1e293b 0%, #0f172a 100%);
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 3rem;
}

.container {
    flex: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 5% 4rem;
    width: 100%;
}

/* BUTTONS */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    font-family: inherit;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(99, 102, 241, 0.5);
}

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

.btn-outline:hover {
    background-color: rgba(99, 102, 241, 0.1);
}

/* CARDS */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.course-card {
    background: rgba(30, 41, 59, 0.6);
    backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
}

.course-card:hover {
    transform: translateY(-8px);
    border-color: var(--primary-color);
    box-shadow: 0 20px 40px rgba(0,0,0,0.4), 0 0 20px rgba(99, 102, 241, 0.15);
}

.course-image {
    width: 100%;
    height: 180px;
    object-fit: cover;
    border-radius: 8px;
    margin-bottom: 1rem;
    background: #2a364a; 
}

.course-title {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.course-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-price {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
}

/* TYPOGRAPHY */
h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #fff 0%, #818cf8 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -1px;
}

h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

/* UTILS */
.text-center { text-align: center; }
.mb-4 { margin-bottom: 1rem; }
.mt-4 { margin-top: 1rem; }

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    border-radius: 8px;
    font-family: inherit;
    transition: var(--transition);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.error-text {
    color: var(--danger-color);
    font-size: 0.85rem;
    margin-top: 0.25rem;
    display: none;
}

/* CHECKOUT SPECIFIC */
.checkout-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    background: var(--surface-color);
    padding: 2.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.summary-card {
    background: var(--bg-color);
    padding: 1.5rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

/* MESSAGES */
.status-card {
    max-width: 500px;
    margin: 4rem auto;
    text-align: center;
    background: var(--surface-color);
    padding: 3rem;
    border-radius: 16px;
    border: 1px solid var(--border-color);
}

.status-icon {
    font-size: 4rem;
    margin-bottom: 1.5rem;
}

.status-icon.success { color: var(--success-color); }
.status-icon.error { color: var(--danger-color); }

/* FOOTER */
footer {
    text-align: center;
    padding: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.9rem;
    background: var(--surface-color);
}

/* RESPONSIVE */
@media (max-width: 768px) {
    .checkout-wrapper {
        grid-template-columns: 1fr;
    }
    .navbar {
        flex-direction: column;
        gap: 1rem;
    }
}