:root {
    --bg-color: #1a1a1a;
    --sidebar-bg: #242424;
    --viewer-bg: #111;
    --text-color: #f0f0f0;
    --text-muted: #999;
    --border-color: #333;
    --accent-color: #1a83cf;
}
body, html {
    height: 100%;
    margin: 0;
    font-family: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    overflow: hidden;
}
.page {
    display: flex;
    height: 100%;
}
#sidebar {
    width: 230px;
    flex-shrink: 0;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    padding: 15px;
    box-sizing: border-box;
    position: relative;
    transition: margin-left 0.3s ease-in-out;
    overflow-y: auto;
}
#sidebar h1 {
    margin-top: 0;
    font-size: 1.5em;
    text-align: center;
}
#issue-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
#issue-list .comic-title {
    font-weight: bold;
    color: var(--text-muted);
    margin-top: 20px;
    padding: 5px 10px;
    cursor: default;
}
#issue-list .issue-item {
    padding: 10px 15px 10px 25px;
    cursor: pointer;
    border-radius: 4px;
    transition: background-color 0.2s;
}
#issue-list .issue-item:hover {
    background-color: #3a3a3a;
}
#issue-list .issue-item.active {
    background-color: var(--accent-color);
    color: white;
    font-weight: bold;
}
#main-content {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    height: 100%;
    position: relative;
}
#viewer-header {
    padding: 10px 20px;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}
#issue-title {
    margin: 0;
    font-size: 1.2em;
}
#issue-artists {
    font-size: 0.9em;
    color: var(--text-muted);
    margin: 5px 0 0;
    min-height: 1.2em;
}
#viewer {
    flex-grow: 1;
    overflow: auto;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    background-color: var(--viewer-bg);
    padding: 10px;
    position: relative;
}
#comic-page {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    display: none; 
}
#loading-indicator {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1.2em;
    color: var(--text-muted);
}
#controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 20px;
    background-color: var(--sidebar-bg);
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
}
.page-controls, .zoom-controls {
    display: flex;
    align-items: center;
    gap: 10px;
    height: 100%;
}
.nav-btn {
    background-color: #3a3a3a;
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    aspect-ratio: 1;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s;
    height: 100%;
    font-size: 1.2em;
    display: flex;
    align-items: center;
    justify-content: center;
}
.nav-btn:hover:not(:disabled) {
    background-color: #4a4a4a;
    border-color: #555;
}
.nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
#variant-btn, #page-jumper, #issue-selector {
    background-color: #3a3a3a;
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 8px 12px;
    border-radius: 4px;
    cursor: pointer;
}
#page-jumper, #zoom-indicator {
    font-size: 1em;
    text-align: center;
    width: 100px;
}
#variant-btn, #controls-spacer {
    display: inline-block;
    width: 150px;
}
#sidebar-btn {
    position: absolute;
    top: 10px;
    left: 10px;
    width: 30px;
    height: 30px;
    padding: 0;
    z-index: 10;
}
.page.sidebar-collapsed #sidebar {
    margin-left: calc(-1 * 230px);
}
.page.sidebar-collapsed #sidebar-open-btn {
    display: block;
}
#mobile-header, #issue-selector {
    display: none;
}
@media (max-width: 768px) {
    .page {
        flex-direction: column;
    }
    #sidebar, #viewer-header, #sidebar-btn, #variant-btn, #controls-spacer {
        display: none;
    }
    #mobile-header {
        display: block;
        position: relative; 
        padding: 10px 15px;
        background-color: var(--sidebar-bg);
        border-bottom: 1px solid var(--border-color);
        text-align: center;
        width: 100%;
        box-sizing: border-box;
    }
    #mobile-issue-title {
        margin: 0;
        font-size: 1em;
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
    }
    #mobile-issue-artists {
        font-size: 0.8em;
        color: var(--text-muted);
        margin: 4px 0 0;
        min-height: 1em;
    }
    #mobile-variant-btn {
        display: none;
        position: absolute;
        top: 50%;
        left: 15px;
        transform: translateY(-50%);
        width: 40px;
        height: 40px;
        padding: 0;
        font-size: 1.5em;
    }
    .zoom-controls {
        display: none;
    }
    #variant-btn, #controls-spacer {
        display: none !important;
    }
    #main-content {
        height: 100vh;
    }
    #viewer {
        padding: 10px;
        box-sizing: border-box;
    }
    #controls {
        padding: 8px;
        gap: 8px;
        justify-content: space-between;
    }
    .page-controls {
        flex-grow: 1;
        justify-content: center;
    }
    #issue-selector, #page-jumper {
        display: block;
        flex-grow: 1;
        max-width: 35%; 
        -webkit-appearance: none; 
        appearance: none;
    }
    #prev-btn, #next-btn {
        width: 44px;
        height: 44px;
        padding: 0;
        font-size: 1.5em;
        flex-shrink: 0;
    }
    .zoom-controls span {
        font-size: 0.9em;
    }
    #zoom-out-btn, #zoom-in-btn {
        width: 40px;
        height: 40px;
    }
}