:root {
    --primary-color: #8a2be2; /* Purple */
    --secondary-color: #ff8c00; /* Orange */
    --text-color: #333;
    --light-text: #f8f9fa;
    --bg-color: #e6e7ee;
    --shadow-light: 3px 3px 6px #d1d9e6, -3px -3px 6px #ffffff;
    --shadow-dark: inset 2px 2px 5px #d1d9e6, inset -3px -3px 7px #ffffff;
    --shadow-pressed: inset 3px 3px 6px #d1d9e6, inset -3px -3px 6px #ffffff;
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --primary-color: #9d4edd; /* Lighter Purple */
    --secondary-color: #ff9e2c; /* Lighter Orange */
    --text-color: #e0e0e0;
    --light-text: #f8f9fa;
    --bg-color: #2d2d3a;
    --shadow-light: 3px 3px 6px #252532, -3px -3px 6px #353542;
    --shadow-dark: inset 2px 2px 5px #252532, inset -3px -3px 7px #353542;
    --shadow-pressed: inset 3px 3px 6px #252532, inset -3px -3px 6px #353542;
}

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

body {
    font-family: 'Poppins', sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
    transition: var(--transition);
    min-height: 100vh;
    padding-top: 80px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: var(--bg-color);
    box-shadow: var(--shadow-light);
    transition: var(--transition);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
}

.logo {
    font-weight: 700;
    font-size: 1.8rem;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
}

.logo i {
    margin-right: 10px;
    color: var(--secondary-color);
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-left: 30px;
}

nav ul li a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    padding: 8px 15px;
    border-radius: 10px;
    box-shadow: var(--shadow-light);
}

nav ul li a:hover {
    box-shadow: var(--shadow-pressed);
}

nav ul li a.active {
    color: var(--primary-color);
    box-shadow: var(--shadow-pressed);
}

.theme-toggle {
    background: var(--bg-color);
    border: none;
    color: var(--text-color);
    font-size: 1.2rem;
    cursor: pointer;
    margin-left: 20px;
    transition: var(--transition);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    box-shadow: var(--shadow-light);
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    box-shadow: var(--shadow-pressed);
}

.hero {
    padding: 80px 0;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 40px;
    border-radius: 20px;
    box-shadow: var(--shadow-light);
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
    max-width: 100%
    white-space: nowrap;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: fadeInUp 1s ease;
}

.hero-subtitle {
    font-size: 0.9rem;
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    animation: fadeInUp 1s ease 0.2s forwards;
    opacity: 0;
}

.hero-subtitle2 {
    font-size: 0.7rem;
    margin-bottom: 3px;
    margin-top: 20px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    animation: fadeInUp 1s ease 0.2s forwards;
    opacity: 0;
}

.cta-button {
    display: inline-block;
    background: var(--bg-color);
    color: var(--primary-color);
    padding: 15px 30px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    box-shadow: var(--shadow-light);
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
    animation: fadeInUp 1s ease 0.4s forwards;
    opacity: 0;
}

.cta-button:hover {
    box-shadow: var(--shadow-pressed);
    transform: translateY(-3px);
}

.process-section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 60px;
    position: relative;
    color: var(--primary-color);
}

.process-steps {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    margin-top: 20px;
}

.process-step {
    flex: 0 0 calc(33.333% - 30px);
    background: var(--bg-color);
    border-radius: 20px;
    padding: 10px 30px;
    text-align: center;
    box-shadow: var(--shadow-light);
    transition: var(--transition);
    position: relative;
    margin-bottom: 15px;
    transform: translateY(50px);
    opacity: 0;
}

.process-step.animated {
    transform: translateY(0);
    opacity: 1;
}

.process-step:hover {
    transform: translateY(-10px);
}

.step-number {
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.2rem;
    box-shadow: var(--shadow-light);
}

.step-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    color: var(--secondary-color);
}

.step-title {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.step-description {
    font-size: 1rem;
    margin-bottom: 20px;
}

.library-section {
    padding: 80px 0;
}

.papers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 50px;
}

.paper-card {
    background: var(--bg-color);
    border-radius: 20px;
    overflow: hidden;
    box-shadow: var(--shadow-light);
    transition: var(--transition);
    transform: translateY(50px);
    opacity: 0;
}

.paper-card.animated {
    transform: translateY(0);
    opacity: 1;
}

.paper-card:hover {
    transform: translateY(-10px);
}

.paper-image {
    height: 200px;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    position: relative;
    overflow: hidden;
}

.paper-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0.8;
    transition: var(--transition);
}

.paper-card:hover .paper-image img {
    transform: scale(1.1);
    opacity: 1;
}

.paper-content {
    padding: 25px;
}

.paper-title {
    font-size: 1.3rem;
    margin-bottom: 10px;
    line-height: 1.4;
    color: var(--primary-color);
}

.paper-description {
    font-size: 0.9rem;
    margin-bottom: 15px;
    color: var(--text-color);
}

.paper-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 20px;
}

.paper-price {
    font-weight: 700;
    color: var(--secondary-color);
    font-size: 1.2rem;
}

.paper-button {
    background: var(--bg-color);
    color: var(--primary-color);
    padding: 8px 15px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    box-shadow: var(--shadow-light);
}

.paper-button:hover {
    box-shadow: var(--shadow-pressed);
}

.paper-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 15px;
}

.paper-tag {
    background: var(--bg-color);
    padding: 5px 10px;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-color);
    box-shadow: var(--shadow-light);
}

footer {
    background: var(--bg-color);
    color: var(--text-color);
    padding: 20px 0;
    text-align: center;
    box-shadow: var(--shadow-light);
    margin-top: 80px;
}

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

.footer-content a {
    color: var(--text-color);
    margin: 0 15px;
    text-decoration: none;
    transition: var(--transition);
    padding: 8px 15px;
    border-radius: 10px;
    box-shadow: var(--shadow-light);
}

.footer-content a:hover {
    box-shadow: var(--shadow-pressed);
    color: var(--primary-color);
}

.support-email {
    display: flex;
    align-items: center;
}

.support-email i {
    margin-right: 5px;
    color: var(--secondary-color);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Modal styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--bg-color);
    border-radius: 20px;
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    padding: 30px;
    position: relative;
    box-shadow: var(--shadow-light);
    transform: scale(0.8);
    transition: all 0.3s ease;
}

.modal.active .modal-content {
    transform: scale(1);
}

.modal-close {
    position: absolute;
    top: 20px;
    right: 20px;
    background: var(--bg-color);
    border: none;
    font-size: 1.5rem;
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-light);
}

.modal-close:hover {
    box-shadow: var(--shadow-pressed);
    color: var(--primary-color);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--primary-color);
}

.form-control {
    width: 100%;
    padding: 12px 15px;
    border: none;
    border-radius: 10px;
    font-family: 'Poppins', sans-serif;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--bg-color);
    color: var(--text-color);
    box-shadow: var(--shadow-dark);
}

.form-control:focus {
    outline: none;
    box-shadow: var(--shadow-pressed);
}

textarea.form-control {
    min-height: 150px;
    resize: vertical;
}

.modal-title {
    font-size: 1.8rem;
    margin-bottom: 20px;
    text-align: center;
    color: var(--primary-color);
}

/* Mobile responsiveness */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .process-step {
        flex: 0 0 100%;
        margin-bottom: 50px;
    }

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

    nav ul {
        display: none;
    }

    .mobile-menu-btn {
        display: block;
    }
}

.mobile-menu-btn {
    display: none;
    background: var(--bg-color);
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    box-shadow: var(--shadow-light);
}

.mobile-menu-btn:hover {
    box-shadow: var(--shadow-pressed);
}

/* View All button */
.view-all-container {
    text-align: center;
    margin-top: 50px;
}