:root {
    /* Color Palette */
    --primary-color: #4361ee;
    --primary-dark: #3f37c9;
    --primary-light: #4895ef;
    --secondary-color: #3a0ca3;
    --accent-color: #4cc9f0;
    --success-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f1c40f;
    --text-main: #2b2d42;
    --text-muted: #8d99ae;
    --bg-body: #f8f9fa;
    --bg-card: #ffffff;
    --border-color: #e9ecef;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
}

body {
    font-family: 'Inter', 'Segoe UI', system-ui, sans-serif;
    background-color: var(--bg-body);
    color: var(--text-main);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

/* Navbar Modernization */
.navbar-custom {
    background: var(--bg-card);
    box-shadow: var(--shadow-sm);
    padding: 1rem 0;
}

.navbar-brand {
    font-weight: 800;
    font-size: 1.5rem;
    color: var(--primary-color) !important;
    letter-spacing: -0.5px;
}

.nav-link {
    font-weight: 500;
    color: var(--text-main) !important;
    transition: color 0.2s;
}

.nav-link:hover {
    color: var(--primary-color) !important;
}

.btn-auth {
    border-radius: 50px;
    padding: 0.5rem 1.5rem;
    font-weight: 600;
    transition: transform 0.2s;
}

.btn-auth:hover {
    transform: translateY(-2px);
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 4rem 0;
    border-radius: var(--radius-lg);
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1440 320"><path fill="%23ffffff" fill-opacity="0.1" d="M0,224L48,213.3C96,203,192,181,288,181.3C384,181,480,203,576,224C672,245,768,267,864,261.3C960,256,1056,224,1152,197.3C1248,171,1344,149,1392,138.7L1440,128L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>') bottom no-repeat;
    background-size: cover;
    pointer-events: none;
}

/* Cards */
.card-custom {
    background: var(--bg-card);
    border: 1px solid rgba(0,0,0,0.05);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    height: 100%;
    overflow: hidden;
}

.card-custom:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.card-header-custom {
    background: transparent;
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem;
    font-weight: 700;
    color: var(--text-main);
}

.card-body-custom {
    padding: 1.5rem;
}

/* Questions */
.question-card {
    background: white;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    margin-bottom: 2rem;
    border-left: 5px solid var(--primary-color);
    overflow: hidden;
}

.question-header {
    padding: 1.5rem;
    background: #fff;
}

.question-text {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-main);
    margin-bottom: 1.5rem;
}

.option-item {
    padding: 1rem;
    margin-bottom: 0.8rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.option-item:hover {
    background-color: #f0f4ff;
    border-color: var(--primary-light);
}

.option-item.correct {
    background-color: #d1fae5;
    border-color: var(--success-color);
    color: #065f46;
}

.option-letter {
    width: 32px;
    height: 32px;
    background: var(--border-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.option-item:hover .option-letter {
    background: var(--primary-color);
    color: white;
}

.option-item.correct .option-letter {
    background: var(--success-color);
    color: white;
}

/* Buttons */
.btn-primary-custom {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    transition: all 0.2s;
}

.btn-primary-custom:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(67, 97, 238, 0.3);
}

.btn-outline-custom {
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    background: transparent;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
}

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

/* Search */
.search-wrapper {
    position: relative;
    max-width: 600px;
    margin: 0 auto;
}

.search-input {
    width: 100%;
    padding: 1rem 1.5rem;
    border-radius: 50px;
    border: 2px solid rgba(255,255,255,0.2);
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    color: white;
    font-size: 1.1rem;
    outline: none;
}

.search-input::placeholder {
    color: rgba(255,255,255,0.8);
}

.search-input:focus {
    background: white;
    color: var(--text-main);
    border-color: white;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

/* Profile */
.profile-header {
    background: white;
    border-radius: var(--radius-md);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: center;
    gap: 2rem;
    margin-bottom: 2rem;
}

.profile-avatar {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid white;
    box-shadow: var(--shadow-md);
}

.badge-pro {
    background: linear-gradient(45deg, #f1c40f, #f39c12);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 50px;
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    box-shadow: 0 4px 10px rgba(241, 196, 15, 0.4);
}

/* Floating Action Button (if needed) */
.fab {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    box-shadow: var(--shadow-lg);
    transition: transform 0.3s;
    z-index: 1000;
}

.fab:hover {
    transform: scale(1.1) rotate(90deg);
}

/* Footer */
footer {
    background: white;
    padding: 3rem 0;
    margin-top: 4rem;
    border-top: 1px solid var(--border-color);
}