* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-white: #ffffff;
    --color-error: #ff0000;
    --color-input-bg: rgba(255, 255, 255, 0.7);
    --color-input-bg-hover: rgba(255, 255, 255, 0.75);
    --color-input-bg-focus: rgba(255, 255, 255, 0.85);
    --color-text: #1a1a1a;
    --color-text-light: #666666;
    --color-placeholder: rgba(26, 26, 26, 0.35);
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    --radius-full: 50%;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.15);
    --z-background: 1;
    --z-content: 10;
    --z-form: 20;
    --z-error: 25;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow: hidden;
    width: 100vw;
    height: 100dvh;
    position: relative;
}

.video-background, .image-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: var(--z-background);
    overflow: hidden;
}

.video-background {
    transition: opacity var(--transition-slow);
}

.video-background.hidden {
    opacity: 0;
    pointer-events: none;
}

.video-background.visible {
    opacity: 1;
}

.video-background video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
}

.image-background {
    background-image: url('/static/auth/poster.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    transition: opacity var(--transition-slow);
}

.image-background.visible {
    opacity: 1;
}

.container {
    position: relative;
    z-index: var(--z-content);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
    min-height: 100dvh;
    padding: var(--spacing-sm);
    padding-bottom: calc(var(--spacing-sm) + env(safe-area-inset-bottom));
}

.login-form {
    width: 100%;
    max-width: 380px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    z-index: var(--z-form);
    transition: opacity var(--transition-slow), transform var(--transition-slow);
    position: relative;
    opacity: 0;
    transform: translateY(16px);
}

.login-form.visible {
    opacity: 1;
    transform: translateY(0);
}

.form-group {
    width: 100%;
}

.form-group input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text);
    background: var(--color-input-bg);
    border: none;
    border-radius: 0;
    outline: none;
    transition: all var(--transition-fast);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    text-align: center;
}

.form-group input::placeholder {
    color: var(--color-placeholder);
    opacity: 1;
}

.form-group input:focus {
    background: var(--color-input-bg-focus);
    box-shadow: var(--shadow-sm);
}

.form-group input:hover:not(:focus) {
    background: var(--color-input-bg-hover);
}

.form-group input:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.error-message {
    position: absolute;
    bottom: calc(100% + var(--spacing-lg));
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    max-width: 380px;
    font-size: 0.875rem;
    color: var(--color-error);
    text-align: center;
    font-weight: 500;
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    z-index: var(--z-error);
    pointer-events: none;
}

.submit-button {
    width: 120px;
    height: 120px;
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--color-text);
    background: var(--color-white);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    outline: none;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.submit-button::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: var(--radius-full);
    background: rgba(0, 0, 0, 0.1);
    transform: translate(-50%, -50%);
    transition: width var(--transition-normal), height var(--transition-normal);
}

.submit-button:hover:not(:disabled)::before {
    width: 100%;
    height: 100%;
}

.submit-button:hover:not(:disabled) {
    transform: scale(1.05);
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.2);
}

.submit-button:active:not(:disabled) {
    transform: scale(0.98);
}

.submit-button:focus-visible {
    outline: 3px solid var(--color-white);
    outline-offset: 4px;
}

.submit-button:disabled {
    cursor: not-allowed;
    opacity: 0.8;
}

.button-text, .button-loader {
    display: flex;
    align-items: center;
    justify-content: center;
}

.spinner {
    width: 24px;
    height: 24px;
    animation: sara-auth-spin 1s linear infinite;
}

@keyframes sara-auth-spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

*:focus-visible {
    outline: 2px solid var(--color-white);
    outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    .login-form {
        transition: none;
    }
    .spinner {
        animation: none;
    }
}

@media (min-width: 1024px) {
    .container {
        padding-bottom: calc(var(--spacing-lg) + env(safe-area-inset-bottom));
    }
    .login-form {
        max-width: 420px;
    }
    .submit-button {
        width: 140px;
        height: 140px;
        font-size: 1.25rem;
    }
    .error-message {
        max-width: 420px;
        font-size: 1rem;
    }
}

@media (max-width: 1023px) and (min-width: 769px) {
    .container {
        padding-bottom: calc(var(--spacing-md) + env(safe-area-inset-bottom));
    }
    .login-form {
        max-width: 380px;
    }
    .submit-button {
        width: 110px;
        height: 110px;
        font-size: 1.0625rem;
    }
}

@media (max-width: 768px) {
    .login-form {
        gap: var(--spacing-sm);
    }
    .form-group input {
        padding: calc(var(--spacing-sm) * 0.875) var(--spacing-md);
        font-size: 0.9375rem;
    }
    .submit-button {
        width: 90px;
        height: 90px;
        font-size: 0.9375rem;
    }
    .error-message {
        font-size: 0.8125rem;
        bottom: calc(100% + var(--spacing-md));
    }
}

@media (max-width: 480px) {
    .submit-button {
        width: 80px;
        height: 80px;
    }
}

@media (max-width: 360px) {
    .submit-button {
        width: 75px;
        height: 75px;
        font-size: 0.875rem;
    }
}

@media (max-height: 600px) and (orientation: landscape) {
    .container {
        justify-content: center;
        padding: var(--spacing-xs);
        padding-bottom: calc(var(--spacing-xs) + env(safe-area-inset-bottom));
    }
    .login-form {
        gap: var(--spacing-xs);
    }
    .submit-button {
        width: 70px;
        height: 70px;
        font-size: 0.875rem;
    }
    .form-group input {
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    .error-message {
        bottom: calc(100% + var(--spacing-sm));
        font-size: 0.75rem;
    }
}

@media (max-height: 500px) {
    .submit-button {
        width: 60px;
        height: 60px;
        font-size: 0.75rem;
    }
}