:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #ec4899;
    --accent-color: #8b5cf6;
    --background-bg: #f3f4f6;
    --card-bg: #ffffff;
    --text-main: #1f2937;
    --text-light: #6b7280;
    --success: #10b981;
    --error: #ef4444;
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.5);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: 'Outfit', sans-serif;
    background: linear-gradient(135deg, #e0e7ff 0%, #f3e8ff 100%);
    color: var(--text-main);
    min-height: 100vh;
    padding: 20px;
    padding-top: 100px;
    /* Compensação para o menu fixo */
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

/* Header */
header {
    text-align: center;
    padding: 60px 20px;
    background: linear-gradient(to right, rgba(255, 255, 255, 0.5), rgba(255, 255, 255, 0.8));
}

h1 {
    font-size: 3rem;
    background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 700;
    margin-bottom: 15px;
    animation: fadeInDown 0.8s ease;
}

.subtitle {
    color: var(--text-light);
    font-size: 1.2rem;
    margin-bottom: 10px;
}

/* Navigation - FIXED MENU */
nav {
    background: rgba(255, 255, 255, 0.95);
    padding: 15px 20px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.nav-links {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
    list-style: none;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-btn {
    padding: 12px 24px;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 12px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(99, 102, 241, 0.2);
}

.nav-btn:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: 0 6px 15px rgba(99, 102, 241, 0.4);
}

/* Main Content */
main {
    padding: 50px 40px;
}

.content-section {
    background: white;
    padding: 40px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    margin-bottom: 30px;
    animation: fadeIn 0.6s ease;
}

h2 {
    font-size: 2.2rem;
    margin-bottom: 20px;
    color: var(--primary-dark);
}

h3 {
    font-size: 1.6rem;
    margin-bottom: 15px;
    color: var(--secondary-color);
}

p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 20px;
    color: var(--text-main);
}

.card {
    background: white;
    padding: 25px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    margin-bottom: 25px;
    border-left: 4px solid var(--secondary-color);
    transition: all 0.3s ease;
}

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

/* Tables */
.table-responsive {
    overflow-x: auto;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    margin-bottom: 30px;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: white;
}

th,
td {
    padding: 15px 20px;
    text-align: left;
}

th {
    background: var(--primary-color);
    color: white;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.9rem;
    letter-spacing: 0.05em;
}

tr:nth-child(even) {
    background: #f9fafb;
}

tr:hover {
    background: #f3f4f6;
}

/* Examples */
.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.example-card {
    background: #f8f9ff;
    padding: 20px;
    border-radius: 12px;
    border-left: 4px solid var(--accent-color);
}

.example-en {
    font-size: 1.15rem;
    color: var(--primary-dark);
    font-weight: 600;
    margin-bottom: 8px;
}

.example-pt {
    color: var(--text-light);
    font-style: italic;
}

/* Exercises */
.exercise {
    background: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    margin-bottom: 20px;
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

.exercise:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.exercise-number {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 5px 15px;
    border-radius: 20px;
    font-weight: 700;
    margin-bottom: 15px;
}

.exercise-question {
    font-size: 1.1rem;
    margin-bottom: 15px;
    color: var(--text-main);
}

.exercise-input {
    width: 100%;
    padding: 12px;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-family: inherit;
    font-size: 1rem;
    margin-bottom: 10px;
    transition: border-color 0.2s;
}

.exercise-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.radio-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 10px;
}

.radio-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    background: #f9fafb;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s;
}

.radio-option:hover {
    background: #f3f4f6;
}

.radio-option input[type="radio"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.btn {
    padding: 10px 20px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px rgba(99, 102, 241, 0.2);
}

.btn:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(99, 102, 241, 0.3);
}

.btn-small {
    padding: 8px 16px;
    font-size: 0.9rem;
}

.answer {
    display: none;
    margin-top: 15px;
    padding: 15px;
    background: #ecfdf5;
    border-left: 4px solid var(--success);
    border-radius: 8px;
    font-weight: 600;
    color: var(--success);
}

.answer.show {
    display: block;
    animation: slideDown 0.3s ease;
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideDown {
    from {
        opacity: 0;
        max-height: 0;
    }

    to {
        opacity: 1;
        max-height: 200px;
    }
}

/* Footer */
footer {
    text-align: center;
    padding: 30px 20px;
    color: var(--text-light);
    font-size: 0.95rem;
    border-top: 1px solid rgba(0, 0, 0, 0.05);
    background: rgba(255, 255, 255, 0.5);
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
    transition: all 0.3s ease;
    opacity: 0;
    visibility: hidden;
    z-index: 1000;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
    animation: float 3s ease-in-out infinite;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-5px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.6);
}

.back-to-top:active {
    transform: translateY(-2px);
}

/* Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 2.2rem;
    }

    h2 {
        font-size: 1.8rem;
    }

    main {
        padding: 30px 20px;
    }

    .content-section {
        padding: 25px 20px;
    }

    .examples-grid {
        grid-template-columns: 1fr;
    }

    .nav-links {
        flex-direction: column;
        align-items: center;
    }
}