/* ========================================
   HEADER COMPONENT
   Site header, logo, and toggle buttons
   ======================================== */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 60px;
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

/* Logo Styles */
.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    font-size: 1.25rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

.logo a span {
    background: linear-gradient(
        135deg,
        #008888 0%,
        #00B8B8 50%,
        #00D4B8 100%
    );
    background-size: 200% auto;
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: textGradientFlow 4s ease infinite;
}

@keyframes textGradientFlow {
    0%, 100% {
        background-position: 0% center;
    }
    50% {
        background-position: 100% center;
    }
}

.logo a:hover span {
    filter: brightness(1.2);
}

.logo svg {
    filter: drop-shadow(0 2px 8px rgba(64, 224, 208, 0.4));
    transition: all 0.3s ease;
}

.logo a:hover svg {
    filter: drop-shadow(0 4px 12px rgba(64, 224, 208, 0.6));
    transform: scale(1.05);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    padding: 0.5rem;
}

/* Header Navigation */
.header-nav {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Theme Toggle Button */
.theme-toggle {
    background: none;
    border: 2px solid var(--border-color);
    color: var(--text-color);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 44px;
    min-height: 44px;
    width: 44px;
    height: 44px;
    touch-action: manipulation;
    transition: all 0.3s ease;
    margin-right: 1rem;
}

.theme-toggle:hover {
    border-color: var(--accent-color);
    background: var(--surface-color);
    transform: scale(1.05);
}

.theme-toggle:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

.theme-toggle svg {
    transition: transform 0.3s ease;
}

.theme-toggle:hover svg {
    transform: rotate(20deg);
}

.theme-toggle .sun-icon {
    display: block;
}

.theme-toggle .moon-icon {
    display: none;
}

/* Sidebar & TOC Toggle Buttons */
.accessibility-toggle,
.sidebar-toggle,
.toc-toggle {
    background: none;
    border: 2px solid var(--border-color);
    color: var(--text-color);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    transition: all 0.3s ease;
    margin-right: 0.5rem;
}

.accessibility-toggle[aria-pressed="true"] {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

.accessibility-toggle:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

.accessibility-toggle:hover,
.sidebar-toggle:hover,
.toc-toggle:hover {
    border-color: var(--accent-color);
    background: var(--surface-color);
    transform: scale(1.05);
}

.sidebar-toggle.active,
.toc-toggle.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

[data-theme="light"] .site-header {
    box-shadow: 0 8px 20px rgba(15, 118, 110, 0.1);
}

[data-theme="light"] .logo a span {
    background: linear-gradient(135deg, #0f766e 0%, #119e90 52%, #0891b2 100%);
    background-size: 200% auto;
}

[data-theme="light"] .theme-toggle,
[data-theme="light"] .accessibility-toggle,
[data-theme="light"] .sidebar-toggle,
[data-theme="light"] .toc-toggle {
    background: rgba(255, 255, 255, 0.9);
    border-color: rgba(15, 118, 110, 0.24);
    box-shadow: 0 4px 12px rgba(15, 118, 110, 0.08);
}

[data-theme="light"] .theme-toggle:hover,
[data-theme="light"] .accessibility-toggle:hover,
[data-theme="light"] .sidebar-toggle:hover,
[data-theme="light"] .toc-toggle:hover {
    background: #f0f8f7;
    border-color: rgba(15, 118, 110, 0.46);
    box-shadow: 0 8px 16px rgba(15, 118, 110, 0.12);
}