header {
    border-bottom: 1px solid var(--color-border-soft);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    backdrop-filter: blur(18px);
    background: rgba(245, 247, 250, 0.72);
}

body:not(.app-active) header {
    border-bottom: none;
    background: transparent !important;
    backdrop-filter: none;
    box-shadow: none;
}

body.dark-mode header {
    background: rgba(7, 17, 29, 0.72);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    min-height: 72px;
    padding: 12px 24px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 14px;
    min-width: 0;
}

.logo-copy {
    display: flex;
    flex-direction: column;
    min-width: 0;
}

.logo-copy span {
    font-weight: 800;
    font-size: 18px;
    color: var(--color-text);
}

.logo-copy small {
    color: var(--color-text-secondary);
    font-size: 12px;
}

.logo-icon {
    width: 52px;
    height: 52px;
    border-radius: 14px;
}

.header-actions {
    display: flex;
    gap: 10px;
    align-items: center;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.app-actions {
    display: none;
}

body.app-active .landing-actions {
    display: none;
}

body.app-active .app-actions {
    display: flex;
}

.btn {
    min-height: 42px;
    padding: 0 16px;
    border-radius: 999px;
    border: 1px solid var(--color-border-soft);
    background-color: rgba(255, 255, 255, 0.78);
    color: var(--color-text);
    cursor: pointer;
    font-size: 14px;
    font-weight: 700;
    transition: all 0.18s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    text-decoration: none;
}

body:not(.app-active) .logo-copy span,
body:not(.app-active) .logo-copy small {
    color: #f5f8ff;
}

body:not(.app-active) .btn {
    background-color: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.1);
    color: #f5f8ff;
}

body.dark-mode .btn {
    background-color: rgba(15, 23, 34, 0.88);
}

.btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
    border-color: rgba(37, 99, 235, 0.24);
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), #0f9b6f 180%);
    color: #f8fbff;
    border-color: transparent;
}

.btn-primary:hover {
    border-color: transparent;
}

.btn-link {
    background: transparent;
    box-shadow: none;
}

@media (max-width: 980px) {
    .header-content {
        align-items: stretch;
        flex-direction: column;
        gap: 14px;
        min-height: auto;
        padding: 14px 20px;
    }

    .logo {
        gap: 12px;
    }

    .logo-icon {
        width: 46px;
        height: 46px;
        border-radius: 12px;
    }

    .logo-copy span {
        font-size: 17px;
        line-height: 1.05;
    }

    .header-actions {
        width: 100%;
        justify-content: flex-start;
    }

    .landing-actions {
        display: grid;
        grid-template-columns: auto minmax(0, 1fr);
        gap: 10px;
        align-items: center;
    }

    .landing-actions .btn-link {
        display: none;
    }

    .landing-actions #themeToggle {
        width: 46px;
        min-width: 46px;
        padding: 0;
    }

    .landing-actions #launchSystemBtn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 640px) {
    header {
        backdrop-filter: blur(22px);
    }

    .header-content {
        gap: 12px;
        padding: 12px 14px;
    }

    .logo {
        gap: 10px;
    }

    .logo-icon {
        width: 40px;
        height: 40px;
        border-radius: 11px;
    }

    .logo-copy span {
        font-size: 15px;
        letter-spacing: -0.02em;
    }

    .logo-copy small {
        display: none;
    }

    .landing-actions {
        grid-template-columns: 42px minmax(0, 1fr);
        gap: 8px;
    }

    .btn {
        min-height: 40px;
        padding: 0 14px;
        font-size: 13px;
    }

    .landing-actions #themeToggle {
        width: 42px;
        min-width: 42px;
        min-height: 40px;
    }

    .landing-actions #launchSystemBtn {
        min-height: 40px;
        border-radius: 14px;
        font-weight: 800;
    }
}

@media (max-width: 480px) {
    .header-content {
        padding: 10px 12px;
    }

    .logo-copy span {
        font-size: 14px;
    }

    .landing-actions {
        gap: 7px;
    }

    .landing-actions #launchSystemBtn {
        font-size: 12px;
    }
}