/* ===================================
   Header Styles - Trend 2026
   =================================== */

header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    width: 100%;
    padding-top: max(0.5rem, env(safe-area-inset-top));
    background: rgba(245, 245, 244, 0.54);
    background: color-mix(in srgb, var(--surface) 56%, transparent);
    backdrop-filter: blur(24px) saturate(185%);
    -webkit-backdrop-filter: blur(24px) saturate(185%);
    border-bottom: none;
    box-shadow:
        0 10px 24px rgba(15, 23, 42, 0.08),
        0 2px 8px rgba(15, 23, 42, 0.04),
        inset 0 1px 0 rgba(255, 255, 255, 0.24);
    transition: background 0.3s ease, box-shadow 0.3s ease, transform 0.3s ease;
}

[data-theme="dark"] header {
    background: rgba(28, 25, 23, 0.5);
    box-shadow: 
        0 0 18px rgba(129, 140, 248, 0.1),
        0 0 42px rgba(129, 140, 248, 0.06),
        inset 0 1px 0 rgba(255, 255, 255, 0.04);
}

header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    padding: 0.7rem 1rem 0.9rem;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1rem;
    font-weight: 800;
    color: var(--accent);
    text-decoration: none;
    transition: color 0.3s ease, transform 0.3s ease;
    letter-spacing: -0.04em;
    white-space: nowrap;
    position: relative;
    z-index: 1001;
}

.logo:hover {
    color: var(--accent-hover);
}

.logo .highlight {
    color: var(--accent-hover);
}

/* Navigation - Hidden on mobile by default */
.nav {
    display: none;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
    list-style: none;
    margin: 0;
    padding: 0;
    position: relative;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: color 0.32s ease, transform 0.32s ease, box-shadow 0.32s ease, letter-spacing 0.32s ease;
    padding: 0.62rem 0.95rem;
    border-radius: 999px;
    white-space: nowrap;
    position: relative;
    overflow: hidden;
    isolation: isolate;
    -webkit-tap-highlight-color: transparent;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.nav-links a::before {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background:
        linear-gradient(135deg, color-mix(in srgb, var(--accent) 22%, white), color-mix(in srgb, var(--accent) 14%, transparent));
    opacity: 0;
    transform: scale(0.82) translateY(0.2rem);
    transition: opacity 0.32s ease, transform 0.4s cubic-bezier(0.22, 1, 0.36, 1);
    z-index: -1;
}

.nav-links a::after {
    content: "";
    position: absolute;
    left: 50%;
    width: calc(100% - 2.4rem);
    bottom: 0.38rem;
    height: 0.16rem;
    border-radius: 999px;
    background: linear-gradient(90deg, var(--accent), color-mix(in srgb, var(--accent) 55%, white));
    opacity: 0.92;
    transform: translateX(-50%) scaleX(0);
    transform-origin: center;
    transition: transform 0.38s cubic-bezier(0.22, 1, 0.36, 1), opacity 0.28s ease;
    z-index: -1;
}

.nav-links a:hover {
    color: var(--text);
    transform: translateY(-2px);
    letter-spacing: -0.01em;
}

.nav-links a:hover::before {
    opacity: 1;
    transform: scale(1);
}

.nav-links a:active {
    transform: translateY(0) scale(0.965);
}

.nav-links a.active {
    color: var(--text);
    font-weight: 700;
    box-shadow:
        0 10px 24px rgba(99, 102, 241, 0.12),
        inset 0 1px 0 rgba(255, 255, 255, 0.28);
    background: transparent;
    letter-spacing: -0.01em;
}

.nav-links a.active::before {
    opacity: 1;
    transform: scale(1);
}

.nav-links a.active::after {
    transform: translateX(-50%) scaleX(1);
}

[data-theme="dark"] .nav-links a.active {
    box-shadow:
        0 0 18px rgba(129, 140, 248, 0.18),
        0 0 34px rgba(129, 140, 248, 0.08);
}

[data-theme="dark"] .nav-links a::before {
    background:
        linear-gradient(135deg, rgba(129, 140, 248, 0.24), rgba(129, 140, 248, 0.08));
}

[data-theme="dark"] .nav-links a:hover,
[data-theme="dark"] .nav-links a.active {
    color: #f5f3ff;
}

/* Theme Toggle */
.theme-toggle {
    width: 2.6rem;
    height: 2.6rem;
    background: rgba(245, 245, 244, 0.84);
    background: color-mix(in srgb, var(--surface) 84%, transparent);
    border: 1px solid rgba(231, 229, 228, 0.78);
    border: 1px solid color-mix(in srgb, var(--border) 78%, transparent);
    font-size: 1rem;
    cursor: pointer;
    color: var(--text-secondary);
    transition: background 0.3s ease, color 0.3s ease, transform 0.3s ease, border-color 0.3s ease;
    padding: 0;
    border-radius: 999px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    position: relative;
    z-index: 1001;
}

.theme-toggle:hover {
    color: var(--accent);
    background: color-mix(in srgb, var(--accent) 10%, var(--surface));
    border-color: color-mix(in srgb, var(--accent) 28%, var(--border));
    transform: translateY(-1px);
}

/* Hamburger Button */
.mobile-menu-btn {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 0.22rem;
    width: 2.85rem;
    height: 2.85rem;
    background: rgba(245, 245, 244, 0.92);
    background: color-mix(in srgb, var(--surface) 84%, transparent);
    border: 1px solid rgba(231, 229, 228, 0.92);
    border: 1px solid color-mix(in srgb, var(--border) 78%, transparent);
    cursor: pointer;
    padding: 0.8rem 0.7rem;
    border-radius: 999px;
    transition: background 0.3s ease, border-color 0.3s ease, transform 0.3s ease;
    flex-shrink: 0;
    position: relative;
    z-index: 1001;
}

.mobile-menu-btn span {
    display: block;
    width: 1.1rem;
    min-width: 1.1rem;
    flex: 0 0 2px;
    height: 2px;
    background-color: var(--text-secondary);
    border-radius: 999px;
    transition: all 0.3s ease;
}

.mobile-menu-btn:hover {
    background: color-mix(in srgb, var(--accent) 10%, var(--surface));
    border-color: color-mix(in srgb, var(--accent) 28%, var(--border));
    transform: translateY(-1px);
}

[data-theme="dark"] .theme-toggle,
[data-theme="dark"] .mobile-menu-btn {
    background: rgba(28, 25, 23, 0.9);
    border-color: rgba(41, 37, 36, 0.95);
}

.mobile-menu-btn:hover span {
    background-color: var(--accent);
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: translateY(6px) rotate(45deg);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0.5);
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: translateY(-6px) rotate(-45deg);
}

/* Mobile Menu - Floating Sheet */
.nav.active {
    display: flex;
    position: fixed;
    top: calc(env(safe-area-inset-top) + 4.8rem);
    left: 0.85rem;
    right: 0.85rem;
    background:
        radial-gradient(circle at top right, color-mix(in srgb, var(--accent) 14%, transparent), transparent 42%),
        linear-gradient(180deg, color-mix(in srgb, var(--surface) 96%, transparent), color-mix(in srgb, var(--surface) 92%, transparent));
    backdrop-filter: blur(24px) saturate(165%);
    -webkit-backdrop-filter: blur(24px) saturate(165%);
    flex-direction: column;
    align-items: stretch;
    z-index: 999;
    padding: 1rem;
    border: 1px solid color-mix(in srgb, var(--border) 78%, transparent);
    border-radius: 1.5rem;
    box-shadow:
        0 24px 60px rgba(0, 0, 0, 0.16),
        0 6px 20px rgba(0, 0, 0, 0.08);
    max-height: min(70vh, 32rem);
    overflow-y: auto;
    animation: mobile-nav-enter 0.35s cubic-bezier(0.22, 1, 0.36, 1);
}

.nav.active .nav-links {
    flex-direction: column;
    align-items: stretch;
    gap: 0.65rem;
}

.nav.active .nav-links a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    padding: 1rem 1.05rem;
    border-radius: 1rem;
    color: var(--text);
    background: color-mix(in srgb, var(--surface) 90%, transparent);
    border: 1px solid color-mix(in srgb, var(--border) 82%, transparent);
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
}

.nav.active .nav-links a::before,
.nav.active .nav-links a::after {
    display: none;
}

.nav.active .nav-links a::after {
    content: "↗";
    font-size: 0.85rem;
    color: var(--text-muted);
    transition: transform 0.25s ease, color 0.25s ease;
}

.nav.active .nav-links a:hover,
.nav.active .nav-links a.active {
    background: color-mix(in srgb, var(--accent) 12%, var(--surface));
    border-color: color-mix(in srgb, var(--accent) 22%, var(--border));
    transform: translateX(4px);
}

.nav.active .nav-links a:hover::after,
.nav.active .nav-links a.active::after {
    color: var(--accent);
    transform: translateX(2px);
}

/* Scroll Effect */
header.scrolled {
    background: color-mix(in srgb, var(--surface) 68%, transparent);
    box-shadow: 
        0 14px 32px rgba(15, 23, 42, 0.1),
        0 4px 14px rgba(15, 23, 42, 0.06),
        inset 0 1px 0 rgba(255, 255, 255, 0.28);
}

[data-theme="dark"] header.scrolled {
    background: rgba(28, 25, 23, 0.58);
    box-shadow: 
        0 0 22px rgba(129, 140, 248, 0.12),
        0 0 52px rgba(129, 140, 248, 0.08),
        inset 0 1px 0 rgba(255, 255, 255, 0.05);
}

/* ===================================
   Desktop - 768px+
   =================================== */
@media (min-width: 768px) {
    header {
        max-width: 90%;
        margin: 0 auto;
        padding-top: 0;
        border-radius: 16px;
        border: 1px solid color-mix(in srgb, var(--border) 78%, transparent);
    }

    header .container {
        padding: 0.55rem 1.5rem;
    }

    .nav {
        display: flex;
    }

    .mobile-menu-btn {
        display: none;
    }

    .theme-toggle {
        width: 2.5rem;
        height: 2.5rem;
    }
}

/* ===================================
   Large Desktop - 1200px+
   =================================== */
@media (min-width: 1200px) {
    header {
        max-width: 70%;
    }
}

@media (max-width: 767px) {
    header .container {
        display: grid;
        grid-template-columns: minmax(0, 1fr) auto auto;
        align-items: center;
    }

    .logo {
        font-size: 1.02rem;
    }

    header.scrolled {
        box-shadow:
            0 20px 44px rgba(15, 23, 42, 0.16),
            0 8px 18px rgba(15, 23, 42, 0.1);
    }
}

@media (max-width: 420px) {
    header .container {
        gap: 0.5rem;
        padding: 0.65rem 0.85rem 0.8rem;
    }

    .logo {
        font-size: 0.94rem;
    }

    .theme-toggle,
    .mobile-menu-btn {
        width: 2.6rem;
        height: 2.6rem;
    }

    .nav.active {
        left: 0.6rem;
        right: 0.6rem;
        top: calc(env(safe-area-inset-top) + 4.45rem);
        padding: 0.85rem;
        border-radius: 1.2rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .nav.active {
        animation: none;
    }
}

@keyframes mobile-nav-enter {
    from {
        opacity: 0;
        transform: translateY(-10px) scale(0.98);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}