/* ============================================
   MODERN HEADER STYLES
   ============================================ */

/* Header Container */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 72px;
    z-index: 1000;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.site-header.scrolled {
    height: 64px;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(20px);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.header-content {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 800;
    color: #f8fafc;
    transition: transform 0.2s ease;
}

.logo:hover {
    transform: translateY(-1px);
}

.logo span {
    color: #f8fafc;
}

.logo strong {
    background: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Main Navigation */
.main-nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.main-nav ul {
    display: flex;
    list-style: none;
    gap: 0.5rem;
    margin: 0;
    padding: 0;
}

.nav-link {
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    font-weight: 600;
    color: #94a3b8;
    border-radius: 0.5rem;
    transition: all 0.2s ease;
}

.nav-link:hover {
    color: #f8fafc;
    background: rgba(255, 255, 255, 0.05);
}

.nav-link.active {
    color: #f8fafc;
    background: rgba(59, 130, 246, 0.2);
}

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

/* Icon Button Base */
.icon-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    padding: 0;
    border: none;
    border-radius: 0.5rem;
    background: rgba(255, 255, 255, 0.05);
    color: #94a3b8;
    cursor: pointer;
    transition: all 0.2s ease;
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #f8fafc;
    transform: translateY(-1px);
}

.icon-btn:active {
    transform: translateY(0);
}

/* Theme Toggle */
.theme-toggle {
    position: relative;
}

.theme-toggle .sun-icon,
.theme-toggle .moon-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    transition: all 0.3s ease;
}

.theme-toggle .sun-icon {
    opacity: 1;
}

.theme-toggle .moon-icon {
    opacity: 0;
    transform: translate(-50%, -50%) rotate(90deg);
}

body.theme-dark .theme-toggle .sun-icon {
    opacity: 0;
    transform: translate(-50%, -50%) rotate(-90deg);
}

body.theme-dark .theme-toggle .moon-icon {
    opacity: 1;
    transform: translate(-50%, -50%) rotate(0deg);
}

/* Unit Toggle */
.unit-toggle .unit-text {
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: -0.025em;
}

/* Dropdown Base */
.dropdown {
    position: relative;
}

.dropdown-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    padding: 0;
    border: none;
    border-radius: 0.5rem;
    background: rgba(255, 255, 255, 0.05);
    color: #94a3b8;
    cursor: pointer;
    transition: all 0.2s ease;
}

.dropdown-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #f8fafc;
}

.dropdown-toggle[aria-expanded="true"] {
    background: rgba(59, 130, 246, 0.2);
    color: #3b82f6;
}

.dropdown-menu {
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 0;
    min-width: 200px;
    padding: 0.5rem;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 0.75rem;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 1000;
}

.dropdown-toggle[aria-expanded="true"] + .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    font-size: 0.875rem;
    color: #94a3b8;
    border-radius: 0.5rem;
    transition: all 0.2s ease;
}

.dropdown-item:hover {
    background: rgba(255, 255, 255, 0.05);
    color: #f8fafc;
}

.dropdown-item.active {
    background: rgba(59, 130, 246, 0.15);
    color: #3b82f6;
}

.dropdown-item .lang-flag {
    font-size: 1.25rem;
    line-height: 1;
}

.dropdown-item .lang-name {
    flex: 1;
    font-weight: 500;
}

.dropdown-item .check-icon {
    color: #3b82f6;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    padding: 0;
    border: none;
    border-radius: 0.5rem;
    background: rgba(255, 255, 255, 0.05);
    cursor: pointer;
    transition: all 0.2s ease;
}

.mobile-menu-toggle span {
    display: block;
    width: 20px;
    height: 2px;
    margin: 0 auto;
    background: #94a3b8;
    border-radius: 2px;
    transition: all 0.3s ease;
}

.mobile-menu-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
}

.mobile-menu-toggle:hover span {
    background: #f8fafc;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Mobile Navigation */
.mobile-nav {
    position: fixed;
    top: 72px;
    left: 0;
    right: 0;
    max-height: calc(100vh - 72px);
    overflow-y: auto;
    background: rgba(15, 23, 42, 0.98);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-20px);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.mobile-nav.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.mobile-nav ul {
    list-style: none;
    padding: 1rem 0;
    margin: 0;
}

.mobile-nav li {
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.mobile-nav li:last-child {
    border-bottom: none;
}

.mobile-nav a {
    display: block;
    padding: 1rem 1.5rem;
    color: #94a3b8;
    font-weight: 500;
    transition: all 0.2s ease;
}

.mobile-nav a:hover {
    background: rgba(255, 255, 255, 0.05);
    color: #f8fafc;
    padding-left: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
    .main-nav {
        display: none;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .header-actions {
        gap: 0.25rem;
    }

    .icon-btn {
        width: 36px;
        height: 36px;
    }
}

@media (max-width: 480px) {
    .logo span {
        font-size: 1rem;
    }

    .site-header {
        height: 64px;
    }

    .mobile-nav {
        top: 64px;
        max-height: calc(100vh - 64px);
    }
}