:root {
    --bg-color: #f4f7f6;
    --text-color: #333;
    --section-bg: #fff;
    --header-bg: #005f73;
    --header-text: #fff;
    --accent-color: #00a9b8;
    --accent-dark: #00778a;
    --tab-bg: #e9f5f9;
    --shadow: rgba(0, 0, 0, 0.1);
    --footer-bg: #001219;
    --viewer-bg: #1a1a1a;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --section-bg: #1e1e1e;
    --header-bg: #003d4d;
    --header-text: #e0e0e0;
    --accent-color: #00d1e0;
    --accent-dark: #00a9b8;
    --tab-bg: #2d2d2d;
    --shadow: rgba(0, 0, 0, 0.5);
    --footer-bg: #000;
    --viewer-bg: #000;
}

/* General Styles */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Header */
header {
    background-color: var(--header-bg);
    color: var(--header-text);
    text-align: center;
    padding: 2rem 0;
    position: relative;
}

header h1 {
    margin: 0;
    font-size: 2.5rem;
}

/* Theme Toggle Button */
.theme-switch-wrapper {
    position: absolute;
    top: 1rem;
    right: 1rem;
    display: flex;
    align-items: center;
}

#theme-toggle {
    background: none;
    border: 2px solid var(--header-text);
    color: var(--header-text);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s ease;
}

#theme-toggle:hover {
    background-color: var(--header-text);
    color: var(--header-bg);
}

/* Main Content */
main {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
}

section {
    background-color: var(--section-bg);
    margin-bottom: 2rem;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 8px var(--shadow);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h2 {
    color: var(--header-bg);
    border-bottom: 2px solid var(--header-bg);
    padding-bottom: 0.5rem;
    margin-top: 0;
}

/* Applications Section Tabs */
.tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    background-color: var(--tab-bg);
    border: 2px solid var(--accent-color);
    border-radius: 4px;
    color: var(--accent-dark);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
}

.tab-btn:hover {
    background-color: var(--accent-color);
    color: white;
}

.tab-btn.active {
    background-color: var(--accent-color);
    color: white;
}

.tab-content {
    display: none;
    background-color: var(--tab-bg);
    padding: 1.5rem;
    border-radius: 4px;
    border-left: 5px solid var(--accent-color);
    animation: fadeIn 0.5s ease;
    color: var(--text-color);
}

.tab-content.active {
    display: block;
}

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

/* 3D Viewer Container */
#zeolite-3d-viewer {
    width: 100%;
    height: 500px;
    background-color: var(--viewer-bg);
    border: none;
    overflow: hidden;
    border-radius: 12px;
    box-shadow: inset 0 0 50px rgba(0,0,0,0.5);
    margin-top: 1rem;
}

/* Contact Form Styles */
#contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: bold;
    color: var(--text-color);
}

.form-group input,
.form-group textarea {
    padding: 0.75rem;
    border: 1px solid var(--accent-color);
    border-radius: 4px;
    background-color: var(--section-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--header-bg);
    box-shadow: 0 0 0 3px rgba(0, 169, 184, 0.2);
}

.submit-btn {
    padding: 1rem;
    background-color: var(--header-bg);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.submit-btn:hover {
    background-color: var(--accent-dark);
    transform: translateY(-2px);
}

.submit-btn:active {
    transform: translateY(0);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0;
    background-color: var(--footer-bg);
    color: #fff;
    margin-top: 4rem;
}

footer p {
    margin: 0;
}