:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --accent-hover: #0ea5e9;
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-border: rgba(148, 163, 184, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    --transition-speed: 0.3s;
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

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

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
    background-image:
        radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.1) 0px, transparent 50%),
        radial-gradient(at 100% 0%, rgba(168, 85, 247, 0.1) 0px, transparent 50%);
}

/* Header */
header {
    padding: 4rem 2rem;
    text-align: center;
    position: relative;
}

h1 {
    font-size: 3.5rem;
    font-weight: 800;
    background: linear-gradient(to right, #38bdf8, #a855f7);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 1rem;
    letter-spacing: -0.05em;
}

header p {
    color: var(--text-secondary);
    font-size: 1.2rem;
    max-width: 600px;
    margin: 0 auto;
}

/* Main Container */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Strategies Section */
.strategies-section {
    margin-bottom: 4rem;
    text-align: center;
}

.strategies-section h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.strategies-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.strategy-card {
    background: rgba(30, 41, 59, 0.4);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 1.5rem;
    text-align: left;
    transition: transform var(--transition-speed), background var(--transition-speed);
    position: relative;
    overflow: hidden;
}

.strategy-card:hover {
    transform: translateY(-3px);
    background: rgba(30, 41, 59, 0.8);
    border-color: var(--accent-color);
}

.strategy-number {
    font-size: 3rem;
    font-weight: 800;
    color: rgba(255, 255, 255, 0.05);
    position: absolute;
    top: -10px;
    right: 10px;
    line-height: 1;
}

.strategy-card h3 {
    color: var(--accent-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    position: relative;
    z-index: 1;
}

.strategy-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    position: relative;
    z-index: 1;
}

/* Grid Layout */
.program-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    padding: 1rem;
}

/* Card Component */
.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 2rem;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    transition: transform var(--transition-speed), box-shadow var(--transition-speed), border-color var(--transition-speed);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    height: 100%;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--glass-shadow);
    border-color: rgba(56, 189, 248, 0.3);
}

.card-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, rgba(56, 189, 248, 0.1), rgba(168, 85, 247, 0.1));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    font-size: 2rem;
}

.card h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.card p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    flex-grow: 1;
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background: linear-gradient(to right, var(--accent-color), #a855f7);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: opacity var(--transition-speed);
    width: 100%;
    text-align: center;
    border: none;
    cursor: pointer;
}

.btn:hover {
    opacity: 0.9;
}

/* Footer */
footer {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-top: 1px solid var(--card-border);
    margin-top: 4rem;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.8);
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 2rem;
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    box-shadow: var(--glass-shadow);
}

.modal-close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 2rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: color var(--transition-speed);
}

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

.modal-content h2 {
    color: var(--text-primary);
    margin-bottom: 1rem;
}

/* File Upload Area */
.file-upload-area {
    border: 2px dashed var(--card-border);
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: border-color var(--transition-speed), background-color var(--transition-speed);
    background-color: rgba(255, 255, 255, 0.02);
}

.file-upload-area:hover {
    border-color: var(--accent-color);
    background-color: rgba(255, 255, 255, 0.05);
}

.file-upload-area p {
    color: var(--text-secondary);
    margin: 0;
}

/* Size Buttons for Icon Converter */
.size-btn {
    padding: 0.5rem 1rem;
    background-color: transparent;
    border: 1px solid var(--card-border);
    border-radius: 4px;
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-speed);
}

.size-btn:hover {
    border-color: var(--accent-color);
    background-color: rgba(56, 189, 248, 0.1);
}

.size-btn.active {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    color: white;
}

/* Tool Button */
.tool-btn {
    background: linear-gradient(to right, #10b981, #059669);
}

.tool-btn:hover {
    opacity: 0.9;
}

/* Unit Converter Tab Buttons */
.unit-tab-btn {
    padding: 0.5rem 1rem;
    background-color: transparent;
    border: 1px solid var(--card-border);
    border-radius: 4px;
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-speed);
    font-family: var(--font-main);
    font-size: 0.9rem;
}

.unit-tab-btn:hover {
    border-color: var(--accent-color);
    background-color: rgba(56, 189, 248, 0.1);
}

.unit-tab-btn.active {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    color: white;
}

/* Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 2.5rem;
    }

    header {
        padding: 3rem 1rem;
    }

    main {
        padding: 1rem;
    }
}