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

:root[data-theme="dark"] {
    --bg:           #000000;
    --chrome-top:   #111111;
    --chrome-bar:   #0e0e0e;
    --tab-inactive: #161616;
    --tab-active:   #000000;
    --tab-border:   rgba(255,255,255,0.08);
    --border:       rgba(255,255,255,0.08);
    --text:         #ffffff;
    --text-dim:     rgba(255,255,255,0.38);
    --text-mid:     rgba(255,255,255,0.62);
    --input-bg:     rgba(255,255,255,0.05);
    --input-focus:  rgba(255,255,255,0.08);
    --btn-bg:       rgba(255,255,255,0.05);
    --btn-hover:    rgba(255,255,255,0.1);
    --accent:       #555555;
    --accent-glow:  rgba(255,255,255,0.06);
    --glass:        rgba(8,8,8,0.98);
    --card:         rgba(255,255,255,0.03);
    --danger:       #ff4b4b;
}
:root[data-theme="solar"] {
    --bg:           #070710;
    --chrome-top:   #0d0d1e;
    --chrome-bar:   #0a0a18;
    --tab-inactive: #090916;
    --tab-active:   #070710;
    --tab-border:   rgba(100,120,255,0.12);
    --border:       rgba(100,120,255,0.1);
    --text:         #e8e8ff;
    --text-dim:     rgba(200,200,255,0.35);
    --text-mid:     rgba(200,200,255,0.6);
    --input-bg:     rgba(100,120,255,0.06);
    --input-focus:  rgba(100,120,255,0.1);
    --btn-bg:       rgba(100,120,255,0.07);
    --btn-hover:    rgba(100,120,255,0.13);
    --accent:       #7c9dff;
    --accent-glow:  rgba(124,157,255,0.18);
    --glass:        rgba(7,7,18,0.97);
    --card:         rgba(100,120,255,0.04);
    --danger:       #ff4b4b;
}

html, body {
    height: 100%;
    background: var(--bg);
    font-family: 'DM Sans', system-ui, sans-serif;
    color: var(--text);
    overflow: hidden;
}

#app-shell {
    display: flex;
    flex-direction: column;
    height: 100vh;
    width: 100vw;
}

#tab-strip {
    display: flex;
    align-items: flex-end;
    background: var(--chrome-top);
    padding: 9px 9px 0 9px;
    gap: 2px;
    border-bottom: 1px solid rgba(255,255,255,0.07);
    min-height: 48px;
    flex-shrink: 0;
    overflow-x: auto;
    overflow-y: visible;
    scrollbar-width: none;
    position: relative;
    z-index: 110;
    contain: layout style;
}
#tab-strip::-webkit-scrollbar { display: none; }

#tab-container {
    display: flex;
    gap: 2px;
    align-items: flex-end;
    min-width: 0;
}

.tab-item {
    display: flex;
    align-items: center;
    gap: 7px;
    padding: 0 10px;
    height: 37px;
    min-width: 140px;
    max-width: 220px;
    border-radius: 8px 8px 0 0;
    background: var(--tab-inactive);
    border: 1px solid transparent;
    border-bottom: none;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    color: var(--text-dim);
    flex-shrink: 0;
    position: relative;
    user-select: none;
    transition: background 0.15s, color 0.15s;
    contain: layout style paint;
}
.tab-item.active {
    background: var(--tab-active);
    border-color: var(--tab-border);
    color: var(--text);
    z-index: 2;
}
.tab-item.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--tab-active);
}
.tab-item:hover:not(.active) { background: rgba(255,255,255,0.05); color: var(--text-mid); }

.tab-favicon {
    width: 14px;
    height: 14px;
    border-radius: 3px;
    flex-shrink: 0;
    background: var(--btn-bg);
    object-fit: contain;
}
.tab-label {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: 12px;
}
.tab-close {
    width: 18px;
    height: 18px;
    border-radius: 4px;
    border: none;
    background: none;
    color: var(--text-dim);
    cursor: pointer;
    font-size: 16px;
    line-height: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s, color 0.15s;
    flex-shrink: 0;
    opacity: 0;
}
.tab-item:hover .tab-close,
.tab-item.active .tab-close { opacity: 1; }
.tab-close:hover { background: rgba(255,77,77,0.2); color: var(--danger); }

#new-tab-btn {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    background: none;
    border: 1px solid transparent;
    color: var(--text-dim);
    cursor: pointer;
    font-size: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    margin-bottom: 4px;
    transition: background 0.15s, color 0.15s, border-color 0.15s;
}
#new-tab-btn:hover { background: var(--btn-hover); border-color: var(--border); color: var(--text); }

#omnibar {
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 8px 12px;
    background: var(--chrome-bar);
    border-bottom: 1px solid rgba(255,255,255,0.07);
    flex-shrink: 0;
    z-index: 109;
    contain: layout style;
}

.omni-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    background: none;
    border: none;
    color: var(--text-mid);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s, color 0.15s;
    flex-shrink: 0;
}
.omni-btn:hover { background: var(--btn-hover); color: var(--text); }
.omni-btn:active { transform: scale(0.91); }
.omni-btn svg { width: 17px; height: 17px; stroke-width: 2.2; pointer-events: none; }

#omnibar-actions { display: flex; align-items: center; gap: 1px; flex-shrink: 0; }

#address-bar-wrap {
    flex: 1;
    position: relative;
    display: flex;
    align-items: center;
}

#course-search-input {
    width: 100%;
    height: 36px;
    padding: 0 42px 0 14px;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 20px;
    color: var(--text);
    font-family: 'DM Mono', monospace;
    font-size: 12px;
    letter-spacing: 0.01em;
    outline: none;
    transition: background 0.18s, border-color 0.18s, box-shadow 0.18s;
}
#course-search-input::placeholder { color: var(--text-dim); font-family: 'DM Sans', sans-serif; font-size: 12.5px; }
#course-search-input:hover { background: var(--input-focus); border-color: rgba(255,255,255,0.14); }
#course-search-input:focus { background: var(--input-focus); border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-glow); }

#bookmark-star-btn {
    position: absolute;
    right: 10px;
    background: none;
    border: none;
    cursor: pointer;
    color: rgba(255,255,255,0.55);
    display: flex;
    align-items: center;
    padding: 4px;
    transition: color 0.15s, transform 0.15s, background 0.15s;
    z-index: 2;
    border-radius: 5px;
}
#bookmark-star-btn:hover { color: #fff; transform: scale(1.1); background: rgba(255,255,255,0.08); }
#bookmark-star-btn.bookmarked { color: #f5c518; }
#bookmark-star-btn.bookmarked svg { fill: #f5c518; }
#bookmark-star-btn svg { width: 16px; height: 16px; stroke-width: 2; }

#suggestions-dropdown {
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    right: 0;
    background: #1a1a1a;
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 12px;
    overflow: hidden;
    z-index: 500;
    box-shadow: 0 12px 32px rgba(0,0,0,0.6);
    display: none;
}
#suggestions-dropdown.visible { display: block; }

.suggestion-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 9px 14px;
    cursor: pointer;
    font-size: 13px;
    color: var(--text-mid);
    transition: background 0.12s;
    border-bottom: 1px solid rgba(255,255,255,0.04);
    contain: layout style paint;
}
.suggestion-item:last-child { border-bottom: none; }
.suggestion-item:hover,
.suggestion-item.active { background: rgba(255,255,255,0.07); color: var(--text); }
.suggestion-item svg { flex-shrink: 0; opacity: 0.4; width: 14px; height: 14px; }
.suggestion-text { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.suggestion-fill { font-size: 11px; color: var(--text-dim); opacity: 0.5; flex-shrink: 0; padding-left: 6px; }

#content-area {
    flex: 1;
    position: relative;
    overflow: hidden;
    background: var(--bg);
}

#educational-background-canvas {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

#content-viewer { position: absolute; inset: 0; z-index: 6; background: transparent; pointer-events: none; }
#content-viewer.active { background: var(--bg); pointer-events: auto; }

iframe { border: none; width: 100%; height: 100%; display: block; background-color: var(--bg); }

#education-home {
    position: absolute;
    inset: 0;
    z-index: 5;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 40px 200px;
    width: 100%;
}

.logo-text {
    font-family: 'DM Sans', sans-serif;
    font-weight: 700;
    font-size: 72px;
    letter-spacing: -4px;
    background: linear-gradient(160deg, rgba(255,255,255,0.45) 0%, #fff 40%, rgba(255,255,255,0.4) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 30px;
    line-height: 1;
}

.home-search-wrap {
    width: 100%;
    max-width: 600px;
    margin: 0 auto 40px auto;
    padding: 0 20px;
}

#main-search-bar {
    width: 100%;
    padding: 16px 20px;
    font-size: 16px;
    border-radius: 8px;
    background: rgba(0,0,0,0.3);
    border: 1px solid var(--border);
    color: var(--text);
    font-family: 'DM Sans', sans-serif;
    outline: none;
    transition: border-color 0.2s, background 0.2s, box-shadow 0.2s;
}
#main-search-bar::placeholder { color: var(--text-dim); }
#main-search-bar:focus { border-color: var(--accent); background: rgba(0,0,0,0.45); box-shadow: 0 0 0 3px var(--accent-glow); }
#main-search-bar:hover { background: rgba(0,0,0,0.38); }

.shortcuts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(80px, 80px));
    justify-content: center;
    gap: 16px;
    width: 100%;
    max-width: 600px;
}

.shortcut-tile {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    aspect-ratio: 1 / 1;
    background: transparent;
    border: none;
    border-radius: 12px;
    color: var(--text);
    cursor: pointer;
    transition: transform 0.2s, background 0.2s;
    padding: 8px;
    contain: layout style paint;
}
.shortcut-tile:hover { transform: scale(1.05); background: rgba(255,255,255,0.05); }
.shortcut-tile:hover .delete-shortcut,
.shortcut-tile:hover .edit-shortcut { opacity: 1; }
.shortcut-tile img { width: 40px; height: 40px; border-radius: 10px; margin-bottom: 8px; }
.shortcut-tile span { font-size: 11px; font-weight: 500; opacity: 0.7; text-align: center; max-width: 100%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.delete-shortcut { position: absolute; top: 4px; right: 4px; width: 20px; height: 20px; background: rgba(255,77,77,0.95); border: none; border-radius: 50%; color: white; font-size: 13px; cursor: pointer; opacity: 0; transition: opacity 0.2s, transform 0.2s; display: flex; align-items: center; justify-content: center; z-index: 10; }
.delete-shortcut:hover { background: rgba(255,77,77,1); transform: scale(1.15); }

.edit-shortcut { position: absolute; top: 4px; left: 4px; width: 20px; height: 20px; background: rgba(80,80,80,0.9); border: none; border-radius: 50%; color: white; cursor: pointer; opacity: 0; transition: opacity 0.2s, transform 0.2s; display: flex; align-items: center; justify-content: center; z-index: 10; padding: 0; }
.edit-shortcut:hover { background: rgba(120,120,120,1); transform: scale(1.15); }
.edit-shortcut svg { width: 11px; height: 11px; stroke-width: 2.5; pointer-events: none; }

#resource-loading-overlay {
    position: absolute;
    inset: 0;
    background-color: var(--bg);
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 10;
    gap: 16px;
}
#resource-loading-overlay.visible { display: flex; }

.loader-spinner { width: 48px; height: 48px; border: 3px solid rgba(255,255,255,0.15); border-top-color: #fff; border-radius: 50%; animation: spin 0.7s linear infinite; }
#resource-loading-message { color: rgba(255,255,255,0.7); font-size: 12px; font-weight: 500; letter-spacing: 0.3px; }
@keyframes spin { to { transform: rotate(360deg); } }

#top-ad { position: absolute; top: 12px; left: 50%; transform: translateX(-50%); z-index: 8; visibility: hidden; pointer-events: none; display: flex; align-items: center; justify-content: center; width: 468px; height: 60px; }
#top-ad.visible { visibility: visible; pointer-events: auto; }

#home-ads-side { position: absolute; inset: 0; pointer-events: none; visibility: hidden; z-index: 7; }
#home-ads-side.visible { visibility: visible; }

#left-ad { position: absolute; left: 0; top: 50%; transform: translateY(-50%); width: 160px; height: 600px; display: flex; align-items: center; justify-content: center; pointer-events: auto; }
#right-ad { position: absolute; right: 0; top: 50%; transform: translateY(-50%); width: 160px; height: 600px; display: flex; align-items: center; justify-content: center; pointer-events: auto; }

.modal {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    background: #111111;
    padding: 24px;
    border-radius: 16px;
    z-index: 300;
    border: 1px solid rgba(255,255,255,0.09);
    width: 360px;
    box-shadow: 0 32px 64px rgba(0,0,0,0.75);
    max-height: 80vh;
    overflow-y: auto;
    contain: layout style;
}
#learning-preferences-modal { width: 480px; max-width: 90vw; }

.hidden { display: none !important; }

.modal-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 18px; }
.modal-header h2 { margin: 0; font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 2px; color: var(--text-dim); }
.clear-all-btn { background: none; border: none; color: var(--danger); font-size: 11px; font-weight: 600; cursor: pointer; text-transform: uppercase; letter-spacing: 1px; }
.clear-all-btn:hover { opacity: 0.7; }

.list-container { max-height: 380px; overflow-y: auto; display: flex; flex-direction: column; gap: 6px; }

.list-item { display: flex; justify-content: space-between; align-items: center; padding: 11px 14px; background: var(--card); border: 1px solid rgba(255,255,255,0.06); border-radius: 10px; transition: background 0.2s, border-color 0.2s; cursor: pointer; contain: layout style paint; }
.list-item:hover { background: rgba(255,255,255,0.07); border-color: rgba(255,255,255,0.12); }

.setting-row { flex-direction: column; align-items: flex-start; gap: 5px; cursor: default; }
.setting-label { font-size: 10px; font-weight: 700; text-transform: uppercase; color: var(--text-dim); }
.setting-control { width: 100%; background: transparent; border: none; color: var(--text); font-size: 14px; font-weight: 500; outline: none; padding: 3px 0; cursor: pointer; appearance: none; }
.setting-control option { background: #1c1c1e; color: white; }

.modal-close-btn { width: 100%; margin-top: 18px; padding: 13px; background: var(--text); color: var(--bg); border: none; border-radius: 10px; font-weight: 700; font-size: 13px; cursor: pointer; transition: opacity 0.2s; }
.modal-close-btn:hover { opacity: 0.88; }

.secondary-btn { width: 100%; margin-top: 7px; padding: 10px; background: var(--btn-bg); color: var(--text); border: 1px solid var(--border); border-radius: 10px; font-size: 11px; font-weight: 600; cursor: pointer; transition: background 0.2s; }
.secondary-btn:hover { background: var(--btn-hover); }

.add-new-tab-btn { width: 100%; padding: 13px; background: rgba(79,142,255,0.09); border: 1px solid rgba(79,142,255,0.25); border-radius: 10px; color: var(--accent); font-weight: 600; font-size: 13px; cursor: pointer; transition: background 0.2s; display: flex; align-items: center; justify-content: center; gap: 8px; margin-top: 10px; }
.add-new-tab-btn:hover { background: rgba(79,142,255,0.14); }

.tab-modal-item { display: flex; align-items: center; justify-content: space-between; padding: 14px; background: var(--card); border: 1px solid rgba(255,255,255,0.06); border-radius: 12px; transition: background 0.2s, border-color 0.2s; cursor: pointer; gap: 12px; contain: layout style paint; }
.tab-modal-item:hover { background: rgba(255,255,255,0.07); border-color: rgba(255,255,255,0.12); }
.tab-modal-item.active { background: var(--accent-glow); border-color: rgba(79,142,255,0.28); }

.tab-modal-favicon { width: 18px; height: 18px; border-radius: 4px; flex-shrink: 0; background: var(--btn-bg); }
.tab-info { flex: 1; overflow: hidden; display: flex; align-items: center; gap: 10px; }
.tab-text { flex: 1; overflow: hidden; }
.tab-modal-title { font-size: 13px; font-weight: 600; margin-bottom: 3px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.tab-modal-url { font-size: 11px; color: var(--text-dim); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.tab-close-btn { width: 26px; height: 26px; border-radius: 6px; background: var(--btn-bg); border: 1px solid var(--border); color: var(--text); display: flex; align-items: center; justify-content: center; cursor: pointer; transition: background 0.2s, border-color 0.2s, color 0.2s; flex-shrink: 0; font-size: 17px; opacity: 0.6; }
.tab-close-btn:hover { background: rgba(255,77,77,0.18); border-color: var(--danger); color: var(--danger); opacity: 1; }

.history-item-content { display: flex; align-items: center; gap: 10px; flex: 1; overflow: hidden; }
.history-favicon { width: 14px; height: 14px; border-radius: 3px; flex-shrink: 0; }
.history-text { flex: 1; overflow: hidden; }
.history-url { font-size: 13px; font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.history-time { font-size: 10px; color: var(--text-dim); margin-top: 2px; }
.history-delete-btn { width: 22px; height: 22px; border-radius: 5px; background: var(--btn-bg); border: 1px solid var(--border); color: var(--text); display: flex; align-items: center; justify-content: center; cursor: pointer; transition: background 0.2s, border-color 0.2s, color 0.2s; flex-shrink: 0; font-size: 15px; opacity: 0.55; }
.history-delete-btn:hover { background: rgba(255,77,77,0.18); border-color: var(--danger); color: var(--danger); opacity: 1; }

.form-group { margin-bottom: 14px; }
.form-group label { display: block; font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: var(--text-dim); margin-bottom: 7px; }
.form-group input { width: 100%; padding: 9px 13px; background: var(--btn-bg); border: 1px solid var(--border); border-radius: 8px; color: var(--text); font-size: 14px; outline: none; transition: background 0.2s, border-color 0.2s; }
.form-group input:focus { background: var(--input-focus); border-color: rgba(255,255,255,0.22); }

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.1); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,0.2); }
* { scrollbar-width: thin; scrollbar-color: rgba(255,255,255,0.1) transparent; }