:root {
    --primary: #667eea;
    --primary-dark: #5a67d8;
    --bg: #f7fafc;
    --card: #ffffff;
    --text: #2d3748;
    --text-light: #718096;
    --border: #e2e8f0;
    --success: #48bb78;
    --error: #e53e3e;
}

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

body {
    font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
    background: linear-gradient(135deg, var(--primary), #764ba2);
    min-height: 100vh;
    color: var(--text);
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 20px;
}

header {
    text-align: center;
    color: white;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
}

header p {
    opacity: 0.9;
    font-size: 1.1em;
}

main {
    background: var(--card);
    border-radius: 16px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text);
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 1em;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.upload-area {
    border: 2px dashed var(--border);
    border-radius: 12px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    margin-bottom: 24px;
    background: var(--bg);
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary);
    background: rgba(102, 126, 234, 0.05);
}

.upload-icon {
    width: 48px;
    height: 48px;
    color: var(--text-light);
    margin-bottom: 16px;
}

.upload-area p {
    color: var(--text);
    margin-bottom: 8px;
}

.upload-area small {
    color: var(--text-light);
}

.browse {
    color: var(--primary);
    font-weight: 600;
    cursor: pointer;
}

.browse:hover {
    text-decoration: underline;
}

.file-list {
    text-align: left;
    margin-top: 20px;
}

.file-item {
    display: flex;
    align-items: center;
    padding: 10px 14px;
    background: white;
    border: 1px solid var(--border);
    border-radius: 8px;
    margin-bottom: 8px;
}

.file-item .name {
    flex: 1;
    font-size: 0.95em;
}

.file-item .remove {
    color: var(--error);
    cursor: pointer;
    font-size: 1.2em;
    padding: 0 8px;
    transition: transform 0.2s;
}

.file-item .remove:hover {
    transform: scale(1.2);
}

button[type="submit"] {
    width: 100%;
    padding: 16px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

button[type="submit"]:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

button[type="submit"]:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.loading {
    text-align: center;
    padding: 60px 40px;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading p {
    color: var(--text-light);
    font-size: 1.1em;
}

.hidden {
    display: none !important;
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.result-header h2 {
    color: var(--text);
}

.download-buttons {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.btn-download {
    padding: 10px 20px;
    background: var(--success);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: opacity 0.2s;
}

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

.btn-new {
    padding: 10px 20px;
    background: var(--text-light);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: opacity 0.2s;
}

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

.calendar-preview {
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
}

.calendar-preview iframe {
    width: 100%;
    height: 650px;
    border: none;
}

footer {
    text-align: center;
    color: white;
    margin-top: 40px;
    opacity: 0.8;
}

footer a {
    color: white;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 600px) {
    .container {
        padding: 20px 15px;
    }

    header h1 {
        font-size: 1.8em;
    }

    main {
        padding: 24px;
    }

    .upload-area {
        padding: 30px 20px;
    }

    .result-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .download-buttons {
        width: 100%;
    }

    .download-buttons button {
        flex: 1;
    }
}