/* General Styles */
:root {
    --primary-color: #007BFF;
    --primary-hover-color: #0056b3;
    --secondary-color: #6c757d;
    --background-color: #f8f9fa;
    --surface-color: #ffffff;
    --text-color: #343a40;
    --heading-color: #212529;
    --border-color: #dee2e6;
    --container-width: 1200px;
    --border-radius: 12px;
    --shadow: 0 10px 25px rgba(0, 0, 0, 0.07);
    --transition-speed: 0.3s;
}

body {
    font-family: 'Poppins', sans-serif;
    color: var(--text-color);
    background-color: var(--background-color);
    margin: 0;
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

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

h1, h2, h3 {
    color: var(--heading-color);
    font-weight: 700;
}

h1 { font-size: 3.2em; line-height: 1.2; }
h2 { font-size: 2.5em; margin-bottom: 24px; }
h3 { font-size: 1.5em; }

section {
    padding: 80px 0;
}

/* Header */
.header {
    background: var(--surface-color);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all var(--transition-speed) ease;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    font-size: 1.8em;
    font-weight: 700;
    color: var(--primary-color);
}

.main-nav {
    display: flex;
    align-items: center;
}

.main-nav a {
    margin: 0 20px;
    font-weight: 600;
    color: var(--text-color);
    position: relative;
    padding: 8px 0;
}

.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width var(--transition-speed) ease;
}

.main-nav a:hover::after {
    width: 100%;
}

.hamburger-menu {
    display: none;
    cursor: pointer;
    font-size: 24px;
    color: var(--text-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(45deg, var(--primary-color), var(--primary-hover-color));
    color: #fff;
    text-align: center;
    padding: 100px 0;
}

.hero h1 {
    color: #fff;
    margin-bottom: 20px;
    font-weight: 700;
}

.hero p {
    font-size: 1.2em;
    max-width: 600px;
    margin: 0 auto 30px;
    opacity: 0.9;
}

/* Buttons */
.btn {
    padding: 14px 30px;
    border-radius: var(--border-radius);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border: none;
    cursor: pointer;
    transition: all var(--transition-speed) ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

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

.btn-primary:hover {
    background-color: var(--primary-hover-color);
    box-shadow: 0 6px 20px rgba(0, 123, 255, 0.4);
    transform: translateY(-3px);
}

.btn-secondary {
    background-color: var(--surface-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: #f1f3f5;
    transform: translateY(-3px);
}


/* Download Section */
.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 32px;
}

.download-card {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.download-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
}

.card-image img {
    width: 100%;
    height: 220px;
    object-fit: cover;
}

.card-content {
    padding: 24px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.card-details {
    flex-grow: 1;
}

.card-details p {
    margin-bottom: 12px;
}

.more-info {
    display: none;
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border-color);
    font-size: 0.9em;
    color: #555;
}

.toggle-more {
    background: none;
    border: none;
    color: var(--primary-color);
    font-weight: 600;
    cursor: pointer;
    padding: 8px 0;
    margin-top: 12px;
    align-self: flex-start;
}

.card-actions {
    margin-top: 24px;
    display: flex;
    gap: 12px;
}

/* About & Contact Sections */
.about-section {
    background-color: var(--surface-color);
}

.contact-section {
    background-color: var(--background-color);
}

.contact-methods {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 32px;
    margin-top: 40px;
}

.contact-card {
    background: var(--surface-color);
    padding: 40px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.contact-card h3 {
    margin-top: 0;
}

#contact-form label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}

#contact-form input,
#contact-form textarea {
    width: 100%;
    padding: 14px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 16px;
    box-sizing: border-box;
    transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
}

#contact-form input:focus,
#contact-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.2);
}

#contact-form button {
    width: 100%;
}

/* Footer */
.footer {
    background-color: var(--heading-color);
    color: rgba(255, 255, 255, 0.8);
    text-align: center;
    padding: 40px 0;
    margin-top: 60px;
}

/* Notification */
.notification {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background-color: #28a745;
    color: white;
    padding: 16px 28px;
    border-radius: var(--border-radius);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    z-index: 1001;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-speed) cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.notification.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* --- Responsive Design --- */

/* Tablets and small desktops */
@media (max-width: 992px) {
    h1 { font-size: 2.8em; }
    h2 { font-size: 2.2em; }
    
    .main-nav {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--surface-color);
        box-shadow: 0 10px 10px rgba(0,0,0,0.05);
        padding: 16px 0;
    }

    .main-nav.active {
        display: flex;
    }

    .main-nav a {
        margin: 12px 24px;
        text-align: center;
    }

    .hamburger-menu {
        display: block;
    }

    #btn-kembali { display: none; }
}

/* Small tablets */
@media (max-width: 768px) {
    h1 { font-size: 2.4em; }
    h2 { font-size: 2em; }
    section { padding: 60px 0; }

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

    .contact-methods {
        grid-template-columns: 1fr;
    }
}

/* Mobile phones */
@media (max-width: 576px) {
    h1 { font-size: 2em; }
    h2 { font-size: 1.8em; }
    
    .hero {
        padding: 80px 0;
    }

    .btn {
        padding: 12px 24px;
        font-size: 0.9em;
    }

    .card-content {
        padding: 20px;
    }
}