/* Koyu theme - ultra premium dark */
[data-theme="koyu"] {
    --color-bg-primary: #0b0d10;
    --color-bg-secondary: #111418;
    --color-bg-tertiary: #181c22;
    --color-text-primary: #f5f7fb;
    --color-text-secondary: #a3adba;
    --color-text-muted: #7b8696;
    --color-accent: #4ea1ff;
    --color-accent-hover: #74b6ff;
    --color-accent-light: rgba(78, 161, 255, 0.18);
    --color-border: #242a35;
    --color-divider: #2c3442;
    --color-overlay: rgba(0, 0, 0, 0.75);
}

[data-theme="koyu"] body {
    background: radial-gradient(1200px 600px at 10% -10%, rgba(78, 161, 255, 0.18), transparent 60%),
                radial-gradient(1200px 600px at 90% -10%, rgba(255, 122, 89, 0.18), transparent 60%),
                #0b0d10;
}

[data-theme="koyu"] .site-header {
    background: rgba(10, 12, 16, 0.9);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(12px);
}

[data-theme="koyu"] .nav-link:hover {
    color: var(--color-accent);
}

[data-theme="koyu"] .search-form {
    background: #0f1217;
    border-color: #202632;
}

[data-theme="koyu"] .search-form input {
    color: #e8edf6;
}

[data-theme="koyu"] .search-form button {
    color: #e8edf6;
}

[data-theme="koyu"] h1,
[data-theme="koyu"] h2,
[data-theme="koyu"] h3,
[data-theme="koyu"] h4 {
    color: #f7f9fc;
    letter-spacing: 0.2px;
}

[data-theme="koyu"] section {
    position: relative;
}

[data-theme="koyu"] section::before {
    content: "";
    position: absolute;
    inset: 0;
    pointer-events: none;
    background: radial-gradient(800px 240px at 20% 0%, rgba(78, 161, 255, 0.08), transparent 60%);
    opacity: 0.8;
}

[data-theme="koyu"] .dropdown-menu,
[data-theme="koyu"] .card,
[data-theme="koyu"] .reveal,
[data-theme="koyu"] .sidebar-content {
    background: rgba(16, 20, 27, 0.88);
    border: 1px solid #232a36;
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.45);
    backdrop-filter: blur(14px);
}

[data-theme="koyu"] .dropdown-menu a:hover {
    background: rgba(78, 161, 255, 0.12) !important;
    color: var(--color-accent) !important;
}

[data-theme="koyu"] .btn,
[data-theme="koyu"] button,
[data-theme="koyu"] .button,
[data-theme="koyu"] a.button {
    background: linear-gradient(135deg, #1c2431 0%, #0f131a 100%);
    color: #e9f1ff;
    border: 1px solid rgba(78, 161, 255, 0.25);
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08), 0 10px 24px rgba(0, 0, 0, 0.35);
}

[data-theme="koyu"] .btn:hover,
[data-theme="koyu"] button:hover,
[data-theme="koyu"] .button:hover,
[data-theme="koyu"] a.button:hover {
    background: linear-gradient(135deg, #243044 0%, #121926 100%);
    border-color: rgba(78, 161, 255, 0.45);
}

[data-theme="koyu"] .hero,
[data-theme="koyu"] .hero-section,
[data-theme="koyu"] .slider,
[data-theme="koyu"] .slide {
    background: linear-gradient(135deg, rgba(17, 22, 31, 0.9), rgba(10, 12, 16, 0.95));
    border: 1px solid #1f2531;
    box-shadow: 0 30px 60px rgba(0, 0, 0, 0.5);
}

[data-theme="koyu"] .site-footer,
[data-theme="koyu"] footer {
    background: #0c0f14;
    border-top: 1px solid #1b2230;
}

[data-theme="koyu"] input,
[data-theme="koyu"] textarea,
[data-theme="koyu"] select {
    background: #0f1319;
    border: 1px solid #232a36;
    color: #e8edf6;
}

[data-theme="koyu"] input::placeholder,
[data-theme="koyu"] textarea::placeholder {
    color: #6c7685;
}

[data-theme="koyu"] .nav-link,
[data-theme="koyu"] .nav-link span,
[data-theme="koyu"] .nav-link i {
    color: #d6dbe3;
}

[data-theme="koyu"] .nav-link:hover,
[data-theme="koyu"] .nav-link:hover i {
    color: var(--color-accent);
}

[data-theme="koyu"] .site-header .logo img {
    filter: drop-shadow(0 6px 18px rgba(0, 0, 0, 0.4));
}

[data-theme="koyu"] .card,
[data-theme="koyu"] .reveal,
[data-theme="koyu"] .sidebar-content {
    background: #11151b;
    border-color: #202634;
    box-shadow: 0 16px 36px rgba(0, 0, 0, 0.4);
}

[data-theme="koyu"] a {
    color: inherit;
}