:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent-color: #f43f5e;
    --accent-hover: #fb7185;
    --border-color: #334155;
}

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

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

header {
    background-color: var(--card-bg);
    padding: 1.2rem 5%;
    box-shadow: 0 2px 15px rgba(0,0,0,0.04);
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-main);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo span {
    color: var(--accent-color);
}

main {
    max-width: 1300px;
    margin: 2.5rem auto;
    padding: 0 20px;
}

.section-header {
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 15px;
}

.section-header h1 {
    font-size: 2.2rem;
    font-weight: 700;
}

.section-header::before {
    content: '';
    display: block;
    width: 6px;
    height: 35px;
    background-color: var(--accent-color);
    border-radius: 4px;
}

.feed-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 30px;
}

.article-card {
    background: var(--card-bg);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    text-decoration: none;
    color: inherit;
}

.article-card > a {
    display: flex;
    flex-direction: column;
    height: 100%;
    text-decoration: none;
    color: inherit;
}

.article-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.8);
    border-color: transparent;
}

.card-image-placeholder {
    height: 180px;
    background: linear-gradient(135deg, #2d3436, #636e72);
    position: relative;
}

.card-image {
    height: 100%;
    width: 100%;
    object-fit: cover;
    object-position: center;
    display: block;
}

img {
    width: 100%;
}

.img-tech { background: linear-gradient(135deg, #0984e3, #74b9ff); }
.img-news { background: linear-gradient(135deg, #00b894, #55efc4); }
.img-violet  { background: linear-gradient(135deg, #6c5ce7, #a29bfe); }
.img-amber   { background: linear-gradient(135deg, #e17055, #fab1a0); }
.img-teal    { background: linear-gradient(135deg, #00cec9, #81ecec); }
.img-crimson { background: linear-gradient(135deg, #d63031, #ff7675); }

.category-badge {
    position: absolute;
    top: 15px;
    left: 15px;
    background: rgba(15, 23, 42, 0.75);
    color: var(--text-main);
    padding: 6px 14px;
    border-radius: 30px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: 0 4px 6px rgba(255,255,255,0.15);
}

.card-content {
    padding: 25px;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.source-name {
    font-size: 0.85rem;
    color: var(--accent-color);
    font-weight: 700;
    text-transform: uppercase;
    margin-bottom: 10px;
    letter-spacing: 0.5px;
}

.card-title {
    font-size: 1.35rem;
    font-weight: 700;
    line-height: 1.4;
    margin-bottom: 15px;
    flex-grow: 1;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border-color);
    padding-top: 15px;
    margin-top: 10px;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.read-more {
    color: var(--accent-color);
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: gap 0.2s;
}

.article-card:hover .read-more {
    gap: 8px;
}

.tool-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--card-bg);
    padding: 15px 25px;
    border-radius: 12px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 15px;
}

.filter-group {
    display: flex;
    align-items: center;
    gap: 12px;
}

.tool-bar label {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    cursor: pointer;
}

#category-filter {
    padding: 8px 15px;
    font-family: inherit;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-main);
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    outline: none;
    min-width: 200px;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    appearance: auto;
}

#category-filter:hover,
#category-filter:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(244, 63, 94, 0.15); 
}

.action-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.search-input {
    padding: 9px 14px;
    background-color: var(--bg-color); 
    color: var(--text-main); 
    border: 1px solid var(--border-color);
    border-radius: 8px; 
    font-size: 1rem;
    outline: none;
    width: 250px;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
    font-family: inherit;
}

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

.search-input:focus {
    border-color: var(--accent-color); 
    box-shadow: 0 0 0 3px rgba(244, 63, 94, 0.15); 
}

#sort-toggle {
    padding: 10px 20px;
    font-family: inherit;
    font-size: 1rem;
    font-weight: 600;
    color: #ffffff;
    background-color: var(--accent-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 120px;
}

#sort-toggle:hover {
    background-color: var(--accent-hover);
}

#sort-toggle:active {
    transform: scale(0.96);
}

.header-subtitle {
    font-weight: 600;
    color: var(--text-muted);
}

.feed-status-message {
    grid-column: 1 / -1;
    text-align: center;
    padding: 20px;
    color: var(--text-muted);
}

.feed-scroll-sentinel {
    height: 1px;
}

.scroll-top-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    border: none;
    background-color: var(--accent-color);
    color: #ffffff;
    font-size: 1.4rem;
    font-weight: 700;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0,0,0,0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 200;
    transition: background-color 0.2s ease, transform 0.1s ease, opacity 0.2s ease;
}

.scroll-top-btn:hover {
    background-color: var(--accent-hover);
}

.scroll-top-btn:active {
    transform: scale(0.92);
}

/* [hidden] samo w sobie ustawia display:none - ta reguła nadpisuje flex
   tylko wtedy, gdy atrybut zostanie usunięty przez JS */
.scroll-top-btn:not([hidden]) {
    display: flex;
}

@media (max-width: 768px) {
    .scroll-top-btn {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
    }

    .tool-bar {
        flex-direction: column;
        align-items: stretch; 
    }
    
    .filter-group {
        flex-direction: column;
        align-items: stretch;
    }

    .action-group {
        flex-direction: column;
        align-items: stretch;
    }

    .search-input, 
    #sort-toggle,
    #category-filter {
        width: 100%; 
    }
}