/* ==========================================
   QuantaraX Blog - Professional Education Platform
   ========================================== */

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

:root {
    /* Professional QuantaraX Colors */
    --primary-purple: #7c3aed;
    --primary-blue: #2563eb;
    --accent-purple: #a78bfa;
    --accent-blue: #60a5fa;

    /* Dark Theme */
    --dark-bg: #0f172a;
    --darker-bg: #020617;
    --card-bg: #1e293b;

    /* Text Colors */
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;

    /* Borders */
    --border-color: #334155;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #7c3aed 0%, #2563eb 100%);
    --gradient-hover: linear-gradient(135deg, #8b5cf6 0%, #3b82f6 100%);
    --gradient-subtle: linear-gradient(135deg, rgba(124, 58, 237, 0.1) 0%, rgba(37, 99, 235, 0.1) 100%);
}

html {
    scroll-behavior: smooth;
    color: white;
    color-scheme: var(--dark-bg);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', sans-serif;
    background-color: var(--dark-bg);
    color: var(--text-primary);
    line-height: 1.6;
    letter-spacing: 0.01em;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== HEADER ===== */
.top-header {
    background: var(--darker-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 14px 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.top-header .container {
    display: flex;
    align-items: center;
    gap: 24px;
}

.logo {
    font-size: 22px;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    white-space: nowrap;
    letter-spacing: 0.5px;
}

.search-box {
    flex: 1;
    display: flex;
    gap: 10px;
    max-width: 650px;
}

.search-input {
    flex: 1;
    padding: 10px 16px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 14px;
    transition: all 0.2s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-purple);
    background: var(--dark-bg);
    box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.1);
}

.search-input::placeholder {
    color: var(--text-muted);
}

.filter-toggle {
    padding: 10px 14px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.filter-toggle:hover {
    border-color: var(--primary-purple);
    background: var(--dark-bg);
}

.filter-toggle.active {
    background: var(--gradient-primary);
    border-color: transparent;
}

.filter-toggle.active svg {
    stroke: white;
}

/* ===== FILTER PANEL ===== */
.filter-panel {
    background: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 14px 0;
    display: none;
    animation: slideDown 0.25s ease;
}

.filter-panel.active {
    display: block;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-12px);
    }

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

.filter-panel .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    flex-wrap: wrap;
}

.filter-options {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 7px 18px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 24px;
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--primary-purple);
    color: var(--text-primary);
    background: var(--gradient-subtle);
}

.filter-btn.active {
    background: var(--gradient-primary);
    border-color: transparent;
    color: white;
}

.sort-select {
    padding: 7px 14px;
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 13px;
    cursor: pointer;
}

.sort-select:focus {
    outline: none;
    border-color: var(--primary-purple);
}

/* ===== BLOG LIST ===== */
.blog-list {
    padding: 28px 0;
    min-height: 70vh;
}

.blog-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    margin-bottom: 20px;
    overflow: hidden;
    transition: all 0.3s ease;
    cursor: pointer;
}

.blog-item:hover {
    border-color: var(--primary-purple);
    transform: translateY(-4px);
    box-shadow: 0 12px 28px rgba(124, 58, 237, 0.2), 0 4px 8px rgba(0, 0, 0, 0.3);
}

.blog-image-container {
    width: 100%;
    height: 220px;
    overflow: hidden;
    background: var(--gradient-subtle);
}

.blog-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    transition: transform 0.4s ease;
}

.blog-item:hover .blog-image {
    transform: scale(1.05);
}

.blog-content {
    padding: 22px 24px;
}

.blog-category {
    display: inline-block;
    padding: 5px 14px;
    background: var(--gradient-subtle);
    border: 1px solid rgba(124, 58, 237, 0.3);
    border-radius: 14px;
    font-size: 11px;
    color: var(--accent-purple);
    text-transform: uppercase;
    letter-spacing: 0.8px;
    font-weight: 600;
    margin-bottom: 12px;
}

.blog-title {
    font-size: 21px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 10px;
    line-height: 1.35;
    letter-spacing: -0.01em;
}

.blog-description {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 18px;
}

.blog-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    padding-top: 14px;
    border-top: 1px solid var(--border-color);
}

.blog-meta {
    display: flex;
    gap: 18px;
    font-size: 13px;
    color: var(--text-muted);
    flex: 1;
}

.blog-date,
.blog-read {
    display: flex;
    align-items: center;
    gap: 5px;
}

.blog-date svg,
.blog-read svg {
    opacity: 0.7;
}

.open-btn {
    padding: 10px 0;
    width: 40%;
    max-width: 140px;
    background: var(--gradient-primary);
    border: none;
    border-radius: 6px;
    color: white;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.25s ease;
    text-align: center;
    letter-spacing: 0.3px;
}

.open-btn:hover {
    background: var(--gradient-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(124, 58, 237, 0.35);
}

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

.no-results {
    text-align: center;
    padding: 80px 24px;
    color: var(--text-muted);
    font-size: 15px;
}

/* ===== FOOTER ===== */
.footer {
    background: var(--darker-bg);
    border-top: 1px solid var(--border-color);
    padding: 28px 0;
    margin-top: 48px;
}

.footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 18px;
}

.footer p {
    color: var(--text-muted);
    font-size: 13px;
}

.footer-links {
    display: flex;
    gap: 24px;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 13px;
    font-weight: 500;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: var(--accent-purple);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
    .top-header .container {
        flex-direction: column;
        align-items: stretch;
        gap: 14px;
    }

    .logo {
        text-align: center;
        font-size: 20px;
    }

    .search-box {
        max-width: 100%;
    }

    .blog-image-container {
        height: 200px;
    }

    .blog-content {
        padding: 18px 20px;
    }

    .blog-footer {
        flex-direction: column;
        align-items: stretch;
        gap: 14px;
    }

    .blog-meta {
        justify-content: center;
    }

    .open-btn {
        width: 100%;
        max-width: 100%;
    }

    .filter-panel .container {
        flex-direction: column;
        align-items: stretch;
    }

    .filter-options {
        justify-content: center;
    }

    .footer .container {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 18px;
    }

    .blog-title {
        font-size: 19px;
    }

    .blog-description {
        font-size: 14px;
    }

    .blog-image-container {
        height: 180px;
    }

    .blog-content {
        padding: 16px 18px;
    }
}

.blog-item.hidden {
    display: none;
}