:root {
    --bg-color: #fafafa;
    --text-color: #0a0a0a;
    --card-bg: #ffffff;
    --card-hover-bg: #f5f5f5;
    --border-color: #d4d4d8;
    --accent-color: #000000;
    --secondary-text: #525252;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    --bg-color: #0a0a0a;
    --text-color: #fafafa;
    --card-bg: #1a1a1a;
    --card-hover-bg: #262626;
    --border-color: #404040;
    --accent-color: #ffffff;
    --secondary-text: #a3a3a3;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color var(--transition-speed), color var(--transition-speed);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 4rem;
    padding-top: 1rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-color);
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background-color: var(--card-bg);
}

.icon {
    width: 1.25rem;
    height: 1.25rem;
}

.sun-icon {
    display: none;
}

[data-theme="dark"] .sun-icon {
    display: block;
}

[data-theme="dark"] .moon-icon {
    display: none;
}

/* Main Grid */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    flex: 1;
}

.tool-card {
    background-color: var(--card-bg);
    border: 1.5px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    text-decoration: none;
    color: var(--text-color);
    transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 180px;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.tool-card:hover {
    transform: translateY(-4px);
    background-color: var(--card-hover-bg);
    border-color: var(--accent-color);
    box-shadow: var(--shadow-md);
}

.card-content {
    z-index: 1;
}

.tool-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}

.tool-desc {
    color: var(--secondary-text);
    font-size: 0.95rem;
    line-height: 1.5;
}

.card-arrow {
    position: absolute;
    bottom: 2rem;
    right: 2rem;
    width: 1.5rem;
    height: 1.5rem;
    opacity: 0;
    transform: translateX(-10px);
    transition: all 0.2s ease;
}

.tool-card:hover .card-arrow {
    opacity: 1;
    transform: translateX(0);
}

.placeholder-card {
    opacity: 0.6;
    cursor: default;
}

.placeholder-card:hover {
    transform: none;
    border-color: var(--border-color);
    background-color: var(--card-bg);
    box-shadow: var(--shadow-sm);
}

/* Footer */
.footer {
    margin-top: 4rem;
    text-align: center;
    color: var(--secondary-text);
    font-size: 0.875rem;
    padding-bottom: 1rem;
}

@media (max-width: 640px) {
    .app-container {
        padding: 1.5rem;
    }

    .header {
        margin-bottom: 2.5rem;
    }

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