/* ===== CSS Variables ===== */
:root {
    /* Colors - Alphastra Dark Theme */
    --color-primary: #5B6CFF;
    --color-primary-hover: #8B96FF;
    --color-primary-dark: #4552CC;
    --color-secondary: #9D7FEA;
    --color-success: #34C759;
    --color-warning: #FF9500;
    --color-error: #FF3B30;

    /* Neutrals - Dark */
    --color-bg: #0a0a0f;
    --color-bg-alt: #111827;
    --color-bg-card: rgba(31, 41, 55, 0.7);
    --color-text: #F9FAFB;
    --color-text-secondary: #9CA3AF;
    --color-border: rgba(255, 255, 255, 0.1);

    /* Glass Effect */
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);

    /* Typography - Apple-inspired scale */
    --text-xs: 0.6875rem;    /* 11px */
    --text-sm: 0.8125rem;    /* 13px */
    --text-base: 1.0625rem;  /* 17px */
    --text-lg: 1.25rem;      /* 20px */
    --text-xl: 1.5rem;       /* 24px */
    --text-2xl: 1.75rem;     /* 28px */
    --text-3xl: 2.125rem;    /* 34px */
    --text-4xl: 2.75rem;     /* 44px */

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro Display', sans-serif;
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
    background-image:
        radial-gradient(ellipse at 20% 20%, rgba(91, 108, 255, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(157, 127, 234, 0.1) 0%, transparent 50%);
    background-attachment: fixed;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--text-4xl); font-weight: 800; }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }

p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-hover);
}

/* ===== Layout ===== */
.section {
    padding: var(--spacing-2xl) var(--spacing-lg);
    max-width: 1200px;
    margin: 0 auto;
}

.section-alt {
    background: rgba(255, 255, 255, 0.02);
}

/* ===== Header & Navigation ===== */
.header {
    position: sticky;
    top: 0;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 100;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--color-text);
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
}

.nav-links a {
    color: var(--color-text-secondary);
    font-weight: 500;
    font-size: var(--text-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.nav-links a:hover {
    color: var(--color-text);
    background: rgba(255, 255, 255, 0.1);
}

/* ===== Hero ===== */
.hero {
    text-align: center;
    padding: var(--spacing-2xl) var(--spacing-lg);
    background: transparent;
}

.hero h1 {
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, #ffffff 0%, var(--color-primary) 50%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: var(--text-lg);
    max-width: 600px;
    margin: 0 auto var(--spacing-xl);
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--text-base);
    font-weight: 600;
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-primary {
    background: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: rgba(91, 108, 255, 0.1);
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn-secondary:hover {
    background: var(--color-primary);
    color: white;
}

/* ===== Cards ===== */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.card {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    border: 1px solid var(--glass-border);
    transition: all var(--transition-base);
}

.card:hover {
    transform: translateY(-4px);
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(91, 108, 255, 0.3);
    box-shadow: 0 8px 32px rgba(91, 108, 255, 0.15);
}

.card h3 {
    margin-bottom: var(--spacing-sm);
}

.card p {
    margin-bottom: var(--spacing-lg);
}

/* ===== Forms ===== */
.form {
    max-width: 500px;
    margin: var(--spacing-xl) auto;
    padding: var(--spacing-xl);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    font-weight: 600;
    font-size: var(--text-sm);
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

input[type="text"],
input[type="email"],
textarea {
    width: 100%;
    padding: var(--spacing-md);
    font-size: var(--text-base);
    font-family: inherit;
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.05);
    color: var(--color-text);
    transition: all var(--transition-fast);
}

input::placeholder,
textarea::placeholder {
    color: var(--color-text-secondary);
}

input:focus,
textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    background: rgba(91, 108, 255, 0.1);
    box-shadow: 0 0 0 3px rgba(91, 108, 255, 0.2);
}

.checkbox-group {
    display: flex;
    gap: var(--spacing-lg);
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 400;
    cursor: pointer;
}

.output {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    font-family: 'Courier New', monospace;
    font-size: var(--text-sm);
    color: var(--color-primary);
    display: none;
}

.output.visible {
    display: block;
}

/* ===== Tabs ===== */
.tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--glass-border);
    padding-bottom: var(--spacing-sm);
}

.tab {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: transparent;
    border: none;
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.tab:hover {
    color: var(--color-text);
    background: rgba(255, 255, 255, 0.1);
}

.tab.active {
    color: var(--color-primary);
    background: rgba(91, 108, 255, 0.2);
}

.tab-panel {
    display: none;
    padding: var(--spacing-lg);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
}

.tab-panel.active {
    display: block;
}

.tab-content {
    margin-bottom: var(--spacing-xl);
}

/* ===== Component Demo ===== */
.component-demo {
    margin: var(--spacing-xl) 0;
    padding: var(--spacing-lg);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
}

.component-demo h3 {
    margin-bottom: var(--spacing-md);
}

/* ===== Modal ===== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    z-index: 1000;
}

.modal-overlay.visible {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--color-bg-alt);
    backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 480px;
    transform: scale(0.9);
    transition: transform var(--transition-base);
}

.modal-overlay.visible .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--glass-border);
}

.modal-header h3 {
    margin: 0;
}

.modal-close {
    background: none;
    border: none;
    font-size: var(--text-xl);
    cursor: pointer;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.modal-close:hover {
    color: var(--color-text);
}

.modal-body {
    padding: var(--spacing-lg);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    border-top: 1px solid var(--glass-border);
}

/* ===== Toast ===== */
.toast-container {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    z-index: 1001;
}

.toast {
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-text);
    color: white;
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    animation: slideIn var(--transition-base) ease;
}

.toast.success {
    background: var(--color-success);
}

.toast.error {
    background: var(--color-error);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ===== Feedback Section ===== */
.feedback-section {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    padding: var(--spacing-2xl) var(--spacing-lg);
}

.feedback-box {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.feedback-box h2 {
    color: white;
    margin-bottom: var(--spacing-sm);
}

.feedback-box > p {
    color: rgba(255, 255, 255, 0.85);
    margin-bottom: var(--spacing-lg);
}

.feedback-form {
    display: flex;
    gap: var(--spacing-md);
    align-items: flex-start;
}

.feedback-form textarea {
    flex: 1;
    padding: var(--spacing-md);
    font-size: var(--text-base);
    font-family: inherit;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.1);
    color: white;
    resize: none;
    transition: box-shadow var(--transition-fast);
}

.feedback-form textarea::placeholder {
    color: rgba(255, 255, 255, 0.6);
}

.feedback-form textarea:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.15);
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.2);
}

.feedback-form .btn {
    white-space: nowrap;
    background: rgba(255, 255, 255, 0.9);
    color: var(--color-primary);
    padding: var(--spacing-md) var(--spacing-xl);
}

.feedback-form .btn:hover {
    background: white;
    transform: translateY(-1px);
}

.feedback-success {
    display: none;
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    color: white;
    font-weight: 500;
}

.feedback-success.visible {
    display: block;
    animation: fadeIn var(--transition-base) ease;
}

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

@media (max-width: 768px) {
    .feedback-form {
        flex-direction: column;
    }

    .feedback-form .btn {
        width: 100%;
    }
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: var(--spacing-xl);
    background: rgba(0, 0, 0, 0.3);
    border-top: 1px solid var(--glass-border);
    color: var(--color-text-secondary);
    font-size: var(--text-sm);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    :root {
        --text-4xl: 2rem;
        --text-3xl: 1.75rem;
        --text-2xl: 1.5rem;
    }

    .nav-links {
        display: none;
    }

    .card-grid {
        grid-template-columns: 1fr;
    }

    .section {
        padding: var(--spacing-xl) var(--spacing-md);
    }
}