body {
    font-family: var(--btir-font);
    background: linear-gradient(160deg, var(--btir-bg) 0%, var(--btir-bg-soft) 100%);
    color: var(--btir-text);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.theme-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 34px;
    height: 32px;
    padding: 0;
    color: var(--btir-text-secondary);
    background: var(--btir-surface);
    border: 1px solid var(--btir-border-strong);
    border-radius: var(--btir-radius-sm);
    cursor: pointer;
    box-shadow: var(--btir-shadow-sm);
    transition: all var(--btir-transition);
}

.theme-toggle:hover {
    color: #ffffff;
    background: var(--btir-primary);
    border-color: var(--btir-primary);
    transform: translateY(-1px);
}

.theme-toggle:active {
    transform: scale(0.95);
}

.theme-toggle svg {
    vertical-align: middle;
}

.auth-card {
    position: relative;
    background: var(--btir-surface);
    border: 1px solid var(--btir-border);
    border-radius: var(--btir-radius-lg);
    box-shadow: var(--btir-shadow-lg);
    padding: 44px 48px;
    width: 470px;
    max-width: 100%;
    animation: slide-up 0.3s ease;
}

.auth-card .theme-toggle {
    position: absolute;
    top: 14px;
    right: 14px;
    box-shadow: none;
    background: transparent;
    border-color: transparent;
}

.auth-card .theme-toggle:hover {
    background: var(--btir-primary-soft);
    border-color: transparent;
}

h1 {
    color: var(--btir-primary);
    margin-bottom: 22px;
    font-size: 24px;
    text-align: center;
}

.auth-card-subtitle {
    margin: -18px 0 22px;
    text-align: center;
    font-size: 13px;
    line-height: 1.4;
    color: var(--btir-text-secondary);
    font-weight: 500;
}

.form-group {
    margin-bottom: 16px;
}

label {
    display: block;
    margin-bottom: 6px;
    color: var(--btir-accent);
    font-weight: 500;
    font-size: 13px;
}

input {
    width: 100%;
    padding: 10px 14px;
    color: var(--btir-text);
    background: var(--btir-surface-muted);
    border: 1px solid var(--btir-border-strong);
    border-radius: var(--btir-radius-sm);
    font-size: 14px;
    transition: border-color var(--btir-transition), box-shadow var(--btir-transition);
}

input:hover {
    border-color: var(--btir-accent);
}

input:focus {
    outline: none;
    border-color: var(--btir-accent);
    box-shadow: 0 0 0 3px rgba(64, 126, 184, 0.14);
}

.submit-btn {
    width: 100%;
    padding: 12px;
    background: linear-gradient(160deg, var(--btir-primary-hover) 0%, var(--btir-primary) 100%);
    color: white;
    border: none;
    border-radius: var(--btir-radius-md);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--btir-transition);
    margin-top: 8px;
}

.submit-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(30, 60, 114, 0.32);
}

.submit-btn:active:not(:disabled) {
    transform: translateY(0);
}

.submit-btn:disabled {
    background: #a0aec0;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.message {
    padding: 10px 12px;
    margin-bottom: 16px;
    border-radius: var(--btir-radius-sm);
    font-size: 13px;
    line-height: 1.5;
    animation: fade-in 0.2s ease;
}

.message.error {
    color: var(--btir-danger);
    background: var(--btir-danger-bg);
}

.message.success {
    color: var(--btir-success);
    background: var(--btir-success-bg);
}

[data-theme="dark"] .message.error {
    color: #fca5a5;
    background: #3b1a1a;
}

[data-theme="dark"] .message.success {
    color: #86efac;
    background: #14351f;
}

.loading-spinner {
    display: inline-block;
    width: 14px;
    height: 14px;
    border: 2px solid rgba(255, 255, 255, 0.45);
    border-top-color: #ffffff;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-right: 6px;
    vertical-align: middle;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes fade-in {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes slide-up {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 560px) {
    body {
        align-items: flex-start;
        min-height: 100vh;
        min-height: 100dvh;
        padding: 16px;
    }

    .auth-card {
        width: 100%;
        margin: auto 0;
        padding: 38px 20px 24px;
        border-radius: var(--btir-radius-md);
    }

    .auth-card .theme-toggle {
        top: 10px;
        right: 10px;
    }

    h1 {
        margin-bottom: 20px;
        padding-right: 36px;
        padding-left: 36px;
        font-size: 22px;
        line-height: 1.35;
    }

    input {
        min-height: 44px;
        padding: 10px 12px;
    }

    .submit-btn {
        min-height: 46px;
    }

    .theme-toggle {
        width: 40px;
        height: 40px;
    }

    .message {
        padding: 10px 12px;
    }
}

@media (max-width: 360px) {
    body {
        padding: 10px;
    }

    .auth-card {
        padding-right: 16px;
        padding-left: 16px;
    }

    h1 {
        font-size: 20px;
    }
}