/* Color Palette */
:root {
    --tan: #D2B48C;
    --cream: #FFFDD0;
    --dark-tan: #8B7355;
    --light-cream: #FFFFF0;
    --text-dark: #3d3d3d;
    --border-light: #E8D4C4;
    --hover-accent: #C9A880;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background: linear-gradient(135deg, var(--light-cream) 0%, var(--cream) 100%);
    min-height: 100vh;
}

html {
    scroll-behavior: smooth;
}

/* Header Styles */
header {
    background: linear-gradient(135deg, var(--tan) 0%, var(--hover-accent) 100%);
    color: white;
    padding: 3rem 1rem;
    box-shadow: 0 4px 12px rgba(211, 180, 140, 0.25);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.95;
    font-weight: 300;
}

/* Main Content */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 1rem;
}

/* Section Styles */
.math-section {
    margin-bottom: 4rem;
    animation: fadeIn 0.6s ease-in;
    border-bottom: 2px solid var(--tan);
}

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

.section-header {
    margin-bottom: 2.5rem;
    padding-bottom: 1.5rem;
}

.section-header h2 {
    font-size: 2rem;
    color: var(--dark-tan);
    margin-bottom: 1rem;
    font-weight: 700;
}

.section-description {
    font-size: 1.05rem;
    color: var(--text-dark);
    line-height: 1.8;
    max-width: 900px;
}

/* PDF Container Grid */
.pdf-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

/* PDF Card Styles */
.pdf-card {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 8px rgba(139, 115, 85, 0.1);
    transition: all 0.3s ease;
    border-top: 4px solid var(--tan);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.pdf-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(211, 180, 140, 0.2);
    border-top-color: var(--hover-accent);
}

.pdf-info {
    flex-grow: 1;
    margin-bottom: 1.5rem;
}

.pdf-info h3 {
    font-size: 1.3rem;
    color: var(--dark-tan);
    margin-bottom: 0.75rem;
    font-weight: 600;
}

.pdf-description {
    font-size: 0.95rem;
    color: #666;
    line-height: 1.7;
}

/* Labels Styles */
.pdf-labels {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin-bottom: 1.5rem;
    margin-top: auto;
}

.label {
    display: inline-block;
    background: linear-gradient(135deg, var(--cream) 0%, var(--light-cream) 100%);
    color: var(--dark-tan);
    padding: 0.4rem 0.9rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid var(--tan);
    transition: all 0.2s ease;
}

.label:hover {
    background: linear-gradient(135deg, var(--tan) 0%, var(--hover-accent) 100%);
    color: white;
    border-color: var(--hover-accent);
}

.label-subtitle {
    display: inline-block;
    background: transparent;
    color: var(--tan);
    padding: 0.4rem 0.9rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid var(--tan);
    transition: all 0.2s ease;
}

.label-subtitle:hover {
    background: var(--tan);
    color: white;
}

/* PDF Link Button Styles */
.pdf-link {
    display: inline-block;
    background: linear-gradient(135deg, var(--tan) 0%, var(--hover-accent) 100%);
    color: white;
    padding: 0.75rem 1.75rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    text-align: center;
    cursor: pointer;
    box-shadow: 0 3px 10px rgba(211, 180, 140, 0.2);
}

.pdf-link:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(211, 180, 140, 0.35);
    background: linear-gradient(135deg, var(--hover-accent) 0%, var(--dark-tan) 100%);
}

.pdf-link:active {
    transform: translateY(0);
}

.pdf-link span {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

/* Section-level Labels (for Colored Space section) */
.math-section > .pdf-labels {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: linear-gradient(135deg, var(--cream) 0%, var(--light-cream) 100%);
    border-radius: 8px;
    border-left: 4px solid var(--tan);
}

/* Footer Styles */
footer {
    background: linear-gradient(135deg, var(--dark-tan) 0%, #6B5344 100%);
    color: white;
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 4rem;
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    main {
        padding: 2rem 1rem;
    }

    .section-header h2 {
        font-size: 1.6rem;
    }

    .section-description {
        font-size: 1rem;
    }

    .pdf-container {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .pdf-card {
        padding: 1.5rem;
    }

    .pdf-info h3 {
        font-size: 1.1rem;
    }

    .math-section {
        margin-bottom: 3rem;
    }

    .section-header {
        margin-bottom: 2rem;
        padding-bottom: 1rem;
    }
}

@media (max-width: 480px) {
    header {
        padding: 2rem 1rem;
    }

    header h1 {
        font-size: 1.6rem;
    }

    .subtitle {
        font-size: 0.9rem;
    }

    main {
        padding: 1.5rem 0.75rem;
    }

    .section-header h2 {
        font-size: 1.4rem;
    }

    .section-description {
        font-size: 0.95rem;
    }

    .pdf-card {
        padding: 1.25rem;
    }

    .pdf-info h3 {
        font-size: 1rem;
    }

    .pdf-link {
        padding: 0.65rem 1.25rem;
        font-size: 0.9rem;
    }

    .label, .label-subtitle {
        font-size: 0.8rem;
        padding: 0.35rem 0.75rem;
    }

    .pdf-labels {
        gap: 0.5rem;
    }
}

/* Print Styles */
@media print {
    header {
        background: var(--tan);
    }

    .pdf-link {
        page-break-inside: avoid;
    }

    body {
        background: white;
    }
}